lsion - PDF Text Files
 TASCAM
TEAC Professional Division
32
-Track Recorder/Reproducer
( OPERATION/MAINTENANCE > 5700029103
The guarantee of performance that we provide
for the 32 must have several restrictions. We
say that the recorder will perform properly
only if it is adjusted properly and the guarantee
is that such adjustment will be possible. How-
ever, we cannot guarantee your skill in adjust-
ment or your technical comprehension of
this manual. Therefore, Basic Daily Setup
is not covered by the Warranty. If your attempts
at internal adjustments of such things as rebias
and record EQ trim are unsuccessful, we must
make a service charge to correct your mistakes.
Recording is an art as well as a science. A
successful recording is often judged primarily
on the quality of sound as art, and we obvious-
ly cannot guarantee that. A company that
makes paint and brushes for artists cannot
say that the paintings made with their pro-
ducts will be well received critically. The
art is the province of the artist. TASCAM can
make no guarantee that the 32 in itself will
assure the quality of the recordings you make.
Your skill as a technician and your abilities
as an artist will be significant factors in the
results you achieve.
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER
CAUTION
RISK OF ELECTRIC SHOCK
(OR BACK). NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL.
DO NOT OPEN
The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the user
to the presence of uninsulated “dangerous voltage” within the product's enclosure that may be of
sufficient magnitude to constitute a risk of electric shock to persans.
The exclamation point within an equilateral triangle is intended to alert the user to the presence of
important operating and maintenance (servicing) instructions in the literature accompanying the
appliance.
WARNING: TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE THIS APPLIANCE
TO RAIN OR MOISTURE.
TABLE OF CONTENTS
Introduction to the 32 and Its Design
Philosophy ............ co... 3
Features and Controls ................. 4
Basic Information. .................... 8
Entering “Record” .................... 9
Voltage Conversion ................... 11
Note for U.K. Customers .............. 11
Connection and Operation of the DX-2D ... 12
M-30 Recording Mixer ................. 15
Accessory Information ................. 17
Specificationsof the 32 ................ 19
The dB; Who, What, Why ............... 21
Impedance Matching and Line Levels ...... 25
Reference Levels ..................... 27
Calibration .......... cin... 29
More Information is Available ........... 30
THEORY OF OPERATION-MAINTENANCE
Cleaning ....cv viii tite teenie 32
Degaussing (Demagnetizing) ............. 33
Test Equipment/Materials .............. 33
1) Alignment Tapes .......ecoereeeono 33
2) VTVMor FET Multimeter .......... 36
3) Signal Generator or Oscillator ....... 36
4) The Oscilloscope ................. 37
5) Test Tapes for the 32 .............. 39
Electrical Adjustment Procedure ......... 40
1) Location of Electrical Adjustments ... 40
2) Reproduce Calibration ............. 41
3) Input Calibration ................. 42
4) AbouttheBias ................... 43
5) Bias Level Adjust ................. 44
6) Bias Trap Adjust........_er_ereseroo 45
7) Record Level Adjust . .............. 45
8) The Peak Adjust Circuit ............ 46
Daily Setup .....roe.ersorererevrenco 47
General Advice on Maintenance .......... 48
Service Chart .............. 5.5... ..... 49
MAINTENANCE
1. Circuit Description
1-1. Logic Used in the Tape Deck ...... 53
1-2. System Control IC .........e.o.e. 53
1-2-1. Pin Assignments and
their Functions ............ 53
1-2-2. Block Diagram .............. 54
1-2-3. Input Signals and
Resulting Modes .. ......... . b4
1-2-4. Mode Transition ...... aaa 55
1-2-5. Operation with more than One
Input Signal ............... 55
1-2-6. Input/Output Levels .......... 55
1-2-7. Initial Reset Circuit .......... 56
1-3. Power Shut-Off Circuit........... 56
1-4. Capstan and Brake Solenoid
Drive Circuit ........ocoe_eccore. 57
1-5. Reel Motor Drive Circuit ......... 59
1-6. Tape Direction Sensing and Counter
Clock Generation Circuit ........ 61
1-7. Counter Clock Pulse ............. 62
18. Motion Sensing Circuit ........... 62
19. F.F.and REW Operation ......... 63
1-10. Electrical Brake System .......... 63
1-11. Counter Zero Return ............ 65
1-12. Punch In/Out Control Circuit ...... 67
1-13. Edit Control Circuit ............. 69
1-14. Rec and Play Mute Signals ....... 69
1-15. Display Circuit ................. 70
1-16. Amplifier Circuit Description ...... 71
1-16-1. Power Muting Circuit ......... 71
1-16-2. Bias and Record Control Circuit . 72
1-16-3. Reproduce Amplifier Circuit ... 74
2. Checks and Adjustments
2-1. Essential Test Equipment
Required .................... 71
2-2. Removing the Panels of the Deck ... 78
2-3. Capstan Thrust Clearance ......... 79
2-4. Brake Mechanism ............... 79
25. BrakeTorque .................. 79
2-6. Reel Motor Torque .............. 80
2-6-1 Take-Up Torque ............. 80
2-6-2 Back Tension ............... 81
2-7. Pinch Roller Pressure ............ 81
2-8. Reel Table Height Adjustment ..... 82
2-9. Таребреей.................... 82
2-10. Wow and Flutter Check .......... 82
2-11. Record/Reproduce Amplifier Checks
and Adjustments .............. 83
Preliminary Adjustments ............. 83
2-11-1. Input Level Calibration ....... 85
2-11-2. Input Meter Calibration ....... 85
2-11-3. Reproduce Level Calibration ... 85
2-11-4. Reproduce Meter Calibration ... 86
2-11-5. Reproduce Frequency
Response ................. 86
2-11-6. Bias Tuning and Bias Trap
Adjustments . .............. 86
2-11-7. Recording Bias Adjustment .... 87
2-11-8. Recording Level Adjustment ... 88
2-119. Frequency Response (Overall) .. 88
2-11-10. Signal-to-Noise Ratio (Overall) .. 89
2-11-11. Erase Ratio. ................ 89
2-11-12. Channel Crosstalk ............ 89
2-11-13. Distortion .........eeee.eecrv.. 90
2-11-14. Headphones Output Level ..... 90
2-11-15, Mic Level Check ............. 90
3. Exploded Views and Parts List ......... 91
Schematic Diagrams ................. Insert
*The M-30 Recording Mixer is optionally available.
Introduction to the 32 and Its Design Philosophy
No matter how elaborate a multichannel tape
recorder is, it doesn't do the job without help.
A lot of equipment is involved, and a lot of
talent as well, The recorder becomes the key-
stone in a system that involves microphones,
mixers, loudspeakers, amplifiers and many
sophisticated electronic devices. Everything
contributes a part to the system of multichannel
recording.
In this general purpose 2 channel recorder/
reproducer we have included the features, cir-
cuits and controls necessary for a wide variety
of applications. For example, true stereo remote
recording with a minimum amount of extra
equipment is made possible by the inclusion of
microphone preamplifiers, pads and headphone
amps.
Either channel may be recorded while audi-
tioning the other in true “sync” (overdub
capability) and a recording can commence
while the tape is rolling {true multitrack “punch-
in” is possible).
CUE and EDIT logics are both supported,
and follow the generally accepted procedures
that professional engineers have made “stand-
ard”. Hand CUE. DUMP EDIT, and inde-
pendent signal selection for the reproduce
amplifiers regardless of record status make
the 32 a useful tool in the business of recording,
whatever that business is, multitrack, multi-
media, remote stereo or fixed location studio
operation.
It has long been our contention that profes-
sionalism is ‘defined by people and what results
they achieve. It's not something that auto-
matically happens when you buy a tape machine
with a lot of tracks, or at a very high price. It's
what you do with the equipment and how
well you do it that makes the point.
In designing the 32, we believe we have been
guided by the multichannel system as it truly
is. We are sure our recorder/reproducer can
deliver the performance necessary to achieve
solid results.
If you would like to comment on our design
philosophy, please feel free to contact us.
Criticism and comment from our owners has
helped us improve our products and our busi-
ness. We welcome all feedback.
Please send in the warranty card. Although
it is not absolutely necessary to insure warran-
ty protection, it will allow us to learn some
things about who you are and what you do
with tape. From time to time we mail out
literature and information of interest to the
multichannel recordist. Let us know where
you are and we'll keep in touch.
*dbx is a trademark of dbx Incorporated, dbx
noise reduction system manufactured under
license from dbx Incorporated.
;
SNA
This recorder /reproducer has a serial number’
located on the rear panel. Please record the |
model number and serial number and retain,
them for your records. ;
| Model number ;
; “Serial number :
Note:
If you notice any differences, either on the outside
or the inside of the unit from the illustrations and
descriptions in this manual, talk to your dealer. He
may have revision sheets that will show manufactur-
ing changes, or notifications of how to deal with any
changes in set-up or maintenance procedures.
Save this manual, refer to it when necessary, and
good luck with your 32.
FEATURES AND CONTROLS
O Reel Tables
Support either 7” reels or hub adaptors when
10-1/2"" reels are used. Use the same size and
kind of reels. See page 8 for details.
@ NAB Hub Adaptors
These can be installed to allow use of 10-1/2”
reels. Rotate adaptor ring CW to fully tighten.
© ZERO RETURN Button
When depressed, counter 0000 may be con-
sidered a one position “autolocator” allowing
rewind ( «« ) to find one spot (0000) on the
tape without the use of the cue lever. You
won't need an audible cue to find this loca-
tion, and accidents to the tape or damage to
the monitor system tweeters will be avoided.
This auto stop function is only possible in
rewind ( « ), the transport will not stop at
0000 if you are using ( »» ) fast forward.
1.1f the rewind time is short, the transport
will stop at 999, not precisely on the “mark”,
but very close.
2.1f the rewind time is long (half a reel of
tape) the transport will cycle between ( << )
and ( »» ) several times and finally come to
rest at counter 999.
Tape slippage will lower the accuracy of the
“stop” point. So, always check by listening
before re-recording. You may not be exactly
4
®
“on-cue’’. Take care.
CAUTION:
Once the ZERO RETURN operations are com-
pleted, make sure to reset this button to ( O
OFF).
© Digital Counter
A 4-digit counter.
© RESET Button
Press this button to obtain “0000” when de-
terming the record start position of the ZERO
RETURN position.
O Impedance Roller
O Tension Arm
O POWER Switch
When depressed ( = ON), the digital counter
and VU meters light. Press again ( © OFF) to
turn off.
O REEL Switch
When large diameter 10-1/2” reels are used,
greater back tension is required for correct
operation. 7” reels require less back tension.
This switch sets the correct amount of back
tension; set it to suit the size of reel you are
using on the supply side.
O SPEED Switch |
LOW (= ) selects a tape speed of 7-1/2 ips
and HIGH (0) selects a tape speed of 15 ips.
® EDIT Switch.
Depress to activate, depress again to release.
CAUTION:
Edit mode may only be activated safely from
STOP. When this button is depressed, the
takeup reel motor is released from transport
logic control. If the recorder is in either fast
foward or rewind, and the EDIT button is
depressed, only the STOP and PLAY buttons
will function. Fast motion in either direction
will not be accepted as a command after STOP
until the EDIT button is released. This pro-
tective restriction must be included in the logic
or the transport may spill tape uncontrollably.
This EDIT feature is used in this way:
When EDIT is depressed, pressing PLAY ( » )
activates the capstan motor and the pinch
roller solenoid regardless of the position of the
takeup tension shutoff arm. The takeup reel
will not move, and the tape will “spill”. This will
allow you to listen to the playback of an un-
wanted section without winding that part
of the tape onto the takeup reel. When you
hear that the section that you wish to remove
(edit out) has completely “spilled”, or “dump-
ed”, a splice can be made, the desired parts can
be joined together, and the unwanted length of
tape discarded. As you can see, the “safety
features” such as brakes and tape tension
detection must be bypassed in order to provide
these edit capabilities, so take care.
® PITCH CONTROL PULL ON Control
Permits a +12 % variation of the tape speed in
the recording or reproducing modes.
Pull out and turn to the left ( -) to decrease the
speed of the tape transport; turn to the right ( +)
to increase the transport speed.
Push in to disengage.
NOTE:
Since this pitch control! is active in record as well
as reproduce, it is wise to check and make sure
that it is disengaged (pushed in) when not wanted.
® CUE Lever
This control will defeat the fast motion tape
lifters. The more pressure you apply, the closer
the tape will come to the heads. This will allow
the reproduce signal to be heard in fast motion
for cueing. Use only enough pressure to hear
the signal. Too much signal will damage the
electronics, and if your monitor system is
5
turned up, high frequency playback signal
will damage your loudspeakers so be sure the
cue lever is not engaged (locked) when in fast
motion. The latch position is provided only for
hand winding the tape to find an edit point.
Push down on the lever to release.
CAUTION:
Use of the cue lever in fast forward or rewind
will greatly accelerate head wear.
O PHONES Volume Control
This control adjusts the output volume for the
headphones.
® PHONES Jack (Tip-Ring-Sleeve)
Connect 8-ohm stereo headphones to this jack
to monitor recordings or to listen to a tape
directly without the use of an amplifier. Maxi-
mum output is 100 miliwatts into 8-ohm stereo
headphones.
“Mono” headphones are not compatible with
this circuit. So check the plug before inserting to
make sure that it has 3 sections. It would also be
prudent to unthread the connector and check
the wiring to make sure that the two audio
leads have not been jointed to make a stereo
headphones into a mono set.
O MIC Input Jacks (2 Conductor, Transformer-
less, Unbalanced)
One input for each channel of the recorder. With-
out the use of the “pad” (ATT switch), the
maximum input signal is -23 dB, 71 mVolt. With
“pad'” (ATT switch depressed) max input be-
comes -3 dB, 700 mVolt. The input impedance
of this circuit is 10k ohms, and will correctly
couple to mics having impedances from 200 to
10.000 ohms. Mics rated lower than 200 ohms
will work, but their output will be lower than
“spec” due to the mismatch in coupling. When 3
wire balanced mics are used, we recommend the
use of an input transformer.
O INPUT SELECT LED Indicators
Indicates which INPUT SELECT buttons have
been activated.
LINE LED: Yellow
MIC LED : Yellow
ATT LED : Yellow
O INPUT SELECT Buttons (L, R)
LINE — Selects line input source signals.
MIC — Selects microphone signals.
ATT — Discards 20 dB worth of signal. The
loss is useful when very loud sounds
cause too high a value of electrical
energy to be generated by the micro-
phones.
This ATT button affects the MIC
circuit only.
® VU Meters
0 VU =.3 Volt. What signal will be shown on
the meters will depend on the settings of the
OUTPUT SELECT buttons. For a comprehen-
sive list of the possible meter logic, see item 24,
OUTPUT SELECT buttons.
@ FUNCTION LED Indicators
Indicates which FUNCTION buttons have been
activated.
@ FUNCTION (L, R) Buttons
Determines the record/reproduce status of the
corresponding channels.
Up — Safe, reproduce or source determined
by OUTPUT SELECT buttons.
Down — Ready to record. If “Record” has been
selected through the transport controls,
depressing this button will begin re-
cording immediately. Qutput of re-
corder switches to source.
@ INPUT Level Controls
For adjusting the MIC or LINE level signal.
Setting has no effect on reproduce. This control
is of a dual concentric type, so either channel can
be adjusted independently.
6 OUTPUT Level Controls
For adjusting the levels of the signals sent to the
OUTPUT (L & R) terminals. This control isof a
dual concentric type, so either channel can be
adjusted independently. Use this control to set
optimum monitoring or listening levels.
@ OUTPUT SELECT Buttons
Select which of three possible sources to feed
the output jacks (rear panel) and VU meter
circuits. The LED's above the buttons show
selection.
INPUT — Meter reads line input to recorder,
input signal appears at output jacks.
Tape signal will not be heard.
SYNC — Used for all normal operations,
recording, sync/reproduce and re-
produce. Meter reads input or head
# 2 play output depending on setting
of function buttons (L or/and R).
REPRO — Selects head # 3. Meter now reads
tape playback. Does not prevent
recording on head #2. Used in
to check performance and record/
play monitoring of tape.
6 OUTPUT SELECT LED Indicators
Indicates which OUTPUT SELECT buttons have
been activated.
INPUT LED : Red
SYNC LED :Yellow
REPRO LED : Green
@ Transport Controls
This group of buttons control the mechanical
action of the transport, and the in/out switching
of the record circuit. The RC-71 remote control
unit (see rear panel for the connection point)
will duplicate this control group. When the
remote is connected, both sets of controls will
be active at the same time.
( > ) Play Button
1. When depressed alone, the tape will advance
at the speed selected by the # 10 SPEED switch
and the #12 PITCH CONTROL.
2. When depressed along with the RECORD
button, any or all tracks that have their FUNC-
TION select buttons IN (record ready) will
begin recording immediately.
3. This transport has a motion sensing circuit
that allows the selection of PLAY directly from
either fast forward or rewind. Press PLAY when
fast winding and the transport will slow, come
briefly to STOP and then enter PLAY by itself.
( >» ) Fast Forward Button
( « ) Rewind Button
Rewind time is 90 seconds for a 10-1/2” reel,
1-1/2 mil tape.
STOP Button
RECORD Button
Depressing this button by itself will have no
effect. To begin recording, several conditions
must first be met.
1. One or more FUNCTION select buttons must
be IN (record ready)
2. To enable the record logic, the PLAY button
must be depressed simultaneously with the
RECORD button. If the transport is in PLAY,
press BOTH buttons together and the unit will
go into record mode.
3. Since the PAUSE button can hold the record
logic in an active condition (see next page,
PAUSE button) if PAUSE is active, recording
can start with a one button PLAY command.
4. Since depressing PLAY/RECORD will enable
the record logic when the FUNCTION select
buttons are NOT active, it is possible to begin
recording with this sequence as well as the more
usual ones. Do this;
1. Establish the record active condition by
depressing PLAY and RECORD together, then—
2. Depress one or both FUNCTION select
buttons and recording will commence. This
additional logic is provided when it is necessary
to hear a previously recorded signal up
to the “punch-in” point. If the FUNCTION
select buttons are OUT (safe) the tape signal
CAN appear at the output. If the FUNCTION
buttonsare IN (record ready) only new INPUT
signal can be auditioned and listening to the tape
to find a “Cue” point for the punch-in will not
be possible. When you must listen to the tape, pre-
load the record logic and use the FUNCTION
buttons to begin the recording.
PAUSE Button
This button will stop the tape and the recording
process without disengaging the record logic, to
continue recording, just press the play ( » )
button alone. If a RECORD/PAUSE logic
condition is in effect, allowing this “one key”
return to record mode, the green and red LEDs
above the PAUSE and RECORD buttons will
light. 1
@ RECORD Status Indicator
The red LED lights up when the deck has been
set into the record mode and begins blinking
if the FUNCTION buttons are not depressed.
@ PAUSE Status Indicator
The green LED lights only when PAUSE and
RECORD have been simultaneously pressed.
O Shut Off Arm
The shut off arm will drop power to the capstan
and reel motors if the tape breaks. It's a good
idea to allow it to drop when you take a break
in the middle of a session. Doing this will stop
the constant rotation of the capstan, and will
lengthen the life of the capstan motor bearings.
It is not necessary to unthread the tape. Just
allow it to become slack so that the shut off arm
can drop.
@ Pinch Roller
@ Capstan Shaft
BACK PANEL
6 REMOTE Connector
Allows connection of the optional RC-71
Remote Control Unit.
€ Output Jacks
Output level is -10 dB (0.3 V). Minimum load
impedance is 10k ohms (unbalanced).
6 LINE IN Jacks
Input level is -10 dB (0.3 V). Input impedance is
50k ohms (unbalanced).
6 DBX UNIT CONTROL SIGNAL Connector
This allows connection of the SYSTEM DX-2D
NOISE REDUCTION SYSTEM and supplies con-
trol signal to the dbx system to permit simultane-
ous encode/decode dbx operation. Because of
this “dual process”, no switching is required when
you change function from recording to playback.
The fact that there are separate sections for each
7
function will also allow “off the tape” monitor-
ing when the dbx is used.
© PUNCH IN/OUT REMOTE Connector
(RC-30P)
Allows connection of the optional RC-30P
TASCAM PUNCH IN/OUT REMOTE PEDAL.
® AC Cord
*INPUT and OUTPUT levels
If you do not have access to any test equipment
or test tapes, a good working position for the
output controls would be position “7”. From
that position, careful monitoring and experi-
mentation will help you determine the optimum
setting. The loudest peaks may briefly register
in the red zone, but the input levels should be
reduced if the deflection needles seem to spend
a lot of time in the red zone. For information on
setting the correct input and output levels, see
“Calibration” on page 29.
BASIC INFORMATION
Reel Installation
Small Hub Reels
OUTER SECTION
CENTER SECTION —
DRIVING KEYS
INNER SECTION
DRIVING KEYS
REEL TABLE
Large Hub Reels
NOTCHES IN REEL
CUT-OUTS IN REAR
y PLATE OF ADAPTER
SPACER EARS
INNER RING LE
al SPACER
NOTE:
A metal spacer is mounted on the back of the
reel adaptors and it must be in place when the
NAB standard 10-1/2”' metal reels are used.
Head Configuration
(1)Erase (2) Record/Sync
(9) Repro
Head Head Head
Threading the Tape
Lift the head access cover and release the sync
head shield to gain access for threading.
NOTE:
If you use a reel of tape that has been stored
“tailed out” (See “Editing and Tape Storage”),
it must be placed on the right reel table and re-
wound to the left.
Erasing the Tape
A previously recorded tape is automatically
erased when you make a new recording on it.
For the best-quality recordings, and for con-
venience, we recommend the TEAC E-2A bulk
eraser. This will erase your tapes cleanly in one
pass for the best signal-to-noise ratio. Another
way to erase is to record with the input controls
set to the minimum levels.
Editing and Tape Storage
Never use ordinary adhesive tape for this vital
procedure. Use only the special tape made
exclusively for tape editing.
Monitor with the CUE lever. When you have
located the precise point to make the cut, stop
the tape and mark the back of the tape with a
Chinacraft type pencil at the center of the
reproduce head, and then use the EDIT switch.
With the EDIT switch and ( » ) button de-
pressed, the tape will begin unthreading itself
(dumping) because the take up reel will not be
moving to take up the slack. The use of non-
magnetic tools is highly recommended. A good
quality machine-milled tape-editing block will
help ensure good edits.
Tape should be stored in a cool, dry place well
away from the influence of magnetic fields.
Print-through (the unwanted transfer of magnetic
signals from one part of the tape to an adjacent
part of the tape, causing “echos”) may be re-
duced by winding (NOT fast winding) the
tape onto the take up reel at normal playing
speed for storage. When the tape is played again,
it is first rewound at a high speed onto the supply
reel. This is called storing the tape “tails out”
and is a common practice in many studios. A
helpful idea is to use white leader tape at the
beginning and red leader tape at the tail end.
The analogy with vehicle head and tail lights is
then an easy way to remember which end is
which.
ENTERING ‘RECORD
In any tape recorder that offers “SYNC” or
overdub capabilities (Where a new part may be
added to an already recorded part), many
different methods for entering the record mode
will be necessary. On the 32, there are four ways
to cause the transport to begin recording.
Although all of these different methods can be
inferred by reading the descriptions that list the
action of each group of controls, we'll review all
four methods here. The títle of each method is
the LAST action you perform to make the
process start.
1.PLAY/RECORD. Depress these two buttons
together. Of course, a signal source must be
selected (MIC, MIC ATT or LINE), and one
or more FUNCTION select buttons must be
depressed. This industry standard two button
(interlock) method can be used for almost all
recordings, but it has a drawback. The minute
that you depress a FUNCTION select button,
that track is switched to “source” and you
can't hear a signal that is already on the tape,
even if you press PLAY all by itself. If you
don't need to hear the previously recorded
signal to find the right place to begin your
new part, this method is OK. If you must
hear, use method 2.
2. FUNCTION select. To use this method,
switch the OUTPUT SELECT to SYNC, select
a signal source and with all FUNCTION select
buttons UP (inactive), press PLAY/RECORD
together, this action will start the tape playing
without actually recording. It WILL pre-load
the record logic. It will NOT switch the
output electronics to “source” (new signal
instead of tape playback). You will still be
able to hear the tape. When you hear the cue,
depress the FUNCTION select button(s) and
recording will commence.
3. PLAY. A single button return to the record
mode is possible if a RECORD/PAUSE logic
has been previously selected, see the paragraph
on the PAUSE control on page 7 for a com-
plete description of this logic. This method is
useful when you wish to stop recording, wait
for some undesired part to finish and then
continue recording.
4. REMOTE PEDAL RC-30P. An accessory
pedal is available that will allow you to start
recording with a foot switch. This is ex-
tremely useful to the musician who must
make a “tight” punch-in that requires both
‘hands “on the instrument” at the exact
moment of the “punch”. The foot switch will
NOT start the transport, you must do that,
but it WILL start and stop recording. Here's
How.
Connect the TASCAM PUNCH IN/QUT RE-
MOTE PEDAL to the rear of the 32. Now,
even with both of your hands occupied,
PUNCH QUT can still be performed by using
the remote pedal. While in sync reproduce,
pressing the pedal with your foot initiates
punch-in of the channels for which record
function has been selected. Punch-out is done
by simply pressing the pedal again.
To conclude this section on entering record,
here is a review of all the record related controls
and what they do.
INPUT SELECT BUTTONS: The signal coming
from MIC or LINE is controlled by the INPUT
SELECT buttons.
LINE — Selects line input source signals.
MIC — Selects microphone signals.
ATT — Discards 20dB of signal from the
microphones.
OUTPUT SELECT BUTTONS: The signal
presented at the output terminals is controlled
by the OUTPUT SELECT buttons.
INPUT — will typically be used for source
calibrations during system interface
and set-up procedures. When this
button is depressed, the input signals
are sent directly to the output ter-
minals.
REPRO — will present the reproduce head
signal to the output jacks to monitor
the printed signal on the tape for
reference during recording.
SYNC — will be used for most operations: re-
cording, overdubbing (sync), and re-
produce. The monitoring status is
then determined by the FUNCTION
buttons.
FUNCTION BUTTONS: When the OUTPUT
SELECT is in either the INPUT or REPRO
position, the FUNCTION buttons have the
single purpose of determining the record status.
UP is safe. DOWN is ready-to-record.
When the OUTPUT SELECT is in the SYNC
position, the FUNCTION buttons serve two pur-
poses:
1) they determine the record status — UP is safe,
DOWN is ready-to-record.
2) they determine the monitoring status — UP is
sync/tape reproduce, DOWN is source.
10
VOLTAGE CONVERSION
This deck is adjusted to operate on the electric
voltage specified on the reel tag and packing
carton.
Note: This voltage conversion is not possible on
models sold in the U.S.A., Canada, UK, Australia
or Europe.
For general export units, if it is necessary to
change the voltage requirements of this deck to
match your area, use the following procedures.
Always disconnect power line cord before
making these changes.
1. Disconnect the power cord of the deck from
the source.
2. Remove the bonnet panel and locate the
voltage selector on the side of the deck.
Refer to “2-2 Removing the Panels of the
Deck’ on page 78.
3. To increase the selected voltage, turn the
slotted center post clockwise using a screw-
driver or another suitable tool.
4. To decrease the selected voltage, turn the
slotted center post counter-clockwise.
5. The numerals that appear in the cut-out
window of the voltage selector indicate the
selected voltage.
6. If the desired voltage numerals do not appear
in the cut-out window as you turn the slotted
center post, your deck must be taken to an
authorized TEAC Service Facility for voltage
conversion.
Set voltage for
i Your we
Te Je}
11
NOTE FOR U.K. CUSTOMERS
U.K. Customers Only:
Due to the variety of plugs being used in the
U.K., this unit is sold without an AC plug. Please
request your dealer to install the correct plug to
match the mains power outlet where your unit
will be used as per these instructions.
IMPORTANT
The wires in this mains lead are coloured in
accordance with the following code:
BLUE: NEUTRAL
BROWN: LIVE
As the colours of the wires in the mains lead of
this apparatus may not correspond with the
coloured markings identifying the terminals of
your plug, proceed as follows.
The wire which is coloured BLUE must be con-
nected to the terminal which is marked with the
letter N or coloured BLACK. The wire which is
coloured BROWN must be connected to the
terminal which is marked with the letter L or
coloured RED.
THE APPLIANCE CONFORMS WITH EEC DIREC-
TIVE 87/308/EEC REGARDING INTERFERENCE
SUPPRESSION
CONFORME AL D.M. 13 APRILE 1989
DIRETTIVA CEE/87/308
Bescheinigung des Herstellers/Importeurs
Hiermit wird bescheinigt, daß der/die/das
MAGNETTONBANDGERÄT TASCAM 32
(Gerät, Typ. Bezeichnung)
in Übereinstimmung mit den Bestimmungen der
AMTSBLATT 163/1984, VFG 1045/1984
(Amtsblattverfügung)
funk-entstört ist.
Der Deutschen Bundespost wurde das Inverkehrbringen
dieses Gerätes angezeigt und die Berechtigung zur Uber-
prüfung der Serie auf Einhaltung der Bestimmungen eingeräumt.
TEAC CORPORATION
Name des Herstellers/Importeurs
CONNECTION AND OPERATION OF THE DX-2D
POWER
9 co 3
[1] TASCAM|DX-2D 1)
DBX NOISE REDUCTION SYSTEM
ON a DOFF L R
Ww
The DX-2D is a 2-channel dbx system designed
for integration with the 32 Recorder/Reproducer.
®
AE ET
Note: When the DX-2D is
used together with the 32, en-
corded signal levels displayed
on VU meters will be found
to be of slightly less value
(through compression) than
non-encoded signal levels.
32
IN
el PO
| E DX-2D
OUT
12
DBX Bypass Switch
1. With this DBX NOISE REDUCTION SYS-
TEM both ENCODE/DECODE are in opera-
tion while this switch is in the (© DBX)
position. With this switch in the ( a BYPASS)
position, the DBX circuit is bypassed, which
deactivates the ENCODE/DECODE function.
The switches for each channel (1 — 2) work
independently to facilitate separate function-
ing.
2. With this switch inthe ( = BYPASS) position,
the LED cuts off, and the DBX circuit is
bypassed. Keep this switch in this position
when not using the DBX NOISE REDUC-
TION SYSTEM.
How the DX-2D functions
The DX-2D functions only when connected to
the DBX UNIT CONTROL SIGNAL terminal
of the 32.
Once the DX-2D has been connected, you may
virtually ignore it. The unit is completely auto-
matic. And, because of the design and nature of
this noise reduction system, there is no need for
record or reproduce level match adjustments —
the level is non-critical within nominal toler-
ances; the circuit is stable.
Since decode and encode functions are actuated
by the respective channels of the DX-2D, simul-
taneous dbx NR Encoding/Decoding is possible
without having to switch between ENCODE or
DECODE.
Original Recording
Suppose you are going to record, with OUTPUT
SELECT in the SYNC position, depress FUNC-
TION select buttons 1 and/or 2. LED indicators
will light, signaling ready-to-record.
An encoded signal will be automatically re-
produced when the 32 is started because of the
DX-2D’s ability to simultaneously encode and
decode while the DBX switch is inthe ( O DBX)
position.
HOW THE DX-2D WORKS
The DX-2D is a wide-band compression-expan-
sion system which provides a net noise reduction
(broadband, not just hiss) of a little more than
30 dB. In addition, the compression during
recording permits a net gain in tape headroom of
about 10 dB.
A compression factor of 2:1 is used before re-
cording; then, 1:2 expansionon reproduce. These
13
compression and expansion factors are linear in
decibels and allow the system to produce tape
recordings with over a 100 dB dynamic range —
an important feature, especially when you're
making live recordings. The DX-2D employs
RMS level sensors to eliminate compressor-ex-
pander tracking errors due to phase shifts in the
tape recorder, and provides excellent transient
tracking capabilities.
To achieve a large reduction in audible tape hiss,
without danger of overload or high frequency
self-erasure on the tape, frequency pre-emphasis
and de-emphasis are added to the signal and
RMS level sensors.
If you're an electronic engineer, ali of the above
gab may tell you the whole story of what's going
on in the DX-2D, but if you're not, to make
things a little easier to understand we'll ask you
to use your imagination.
Imagine four little recording engineers in the
box with each of their hands on a volume con-
trol. They are incredibly fast but very stupid, so
you must give them a set of rules. You tell them
to raise signals that are below “0 VU”, and re-
duce signals that are higher than “0 VU”.
The lower the signal is, the more they raise it,
and the higher levels above “0 VU” get lowered
more and more as they go up in level past “0”.
This is the 2:1 compression. You also tell them
to call “0.316 V” “0 VU”. Here they do nothing,
no change except frequency pre-emphasis or
boost. Since you know they are going to keep
the high levels under control, you can raise the
“top end” a bit and still not overload the tape.
Just to keep it simple for them, the boost in
highs is fixed. They put it in all the time, no
matter what level changes they are making. Now
we play tape back, and say OK, do everything
backwards. Levels above “0.316 V” “0 VU” are
raised and levels below “0.316 V” are lowered,
and while you're at it, fellows, take off the extra
top end as well. Follow the rules in reverse. As
long as you don’t confuse them by shifting the
“0 VU” point, they work just great, but — don't
put in more than “0.316 V” as zero VU, and
don't make the tape playback zero anything
other than 10.316 V” either. As we said they're
very dumb and will follow instructions very
precisely. Differing levels will produce decoding
errors.
The reason these errors may not be objection-
able is that people could have played or sung or
whatever with a little more or less dynamics. A
small change won't be as noticeable as a mistake,
but it is not perfect. The tolerance here is not
electronic, it's human. To get exactly what you
put in, it is necessary to get an exact “0 VU”,
0.316 V in and out. The system is level sensitive
although it is realistic to say it is “artistically”
forgiving.
One common mistake we find, is that people
don't check the OUTPUT voltage of the mixer
or other device feeding the DX-2D, and don't
remember that the DX-2D is the first item in the
system (32/DX-2D). “Breathing” and “pump-
ing” can result especially on instruments like
plano and acoustic guitars, if the levels are
seriously mismatched, because of the way the
DX-2D works. 1f your mixer “07 VU is not 0.3
volt, (the DX-2D “standard zero”) the code
process will reflect the fact that all levels are
higher (if the mixer “zero” is 1 volt.) Now,
when you DECODE, the troubles start. The
32 playback electronics cannot safely be set to
this “high” output level, and the decoder will
not “see”, the same levels in playback. Decode
errors will occur.
Consider also the fact that the DX-2D will in-
crease your signal to noise ratio by 30 dB. If you
record at a generally lower level you will avoid
dbx problems and still have quiet tapes. Try
using -5b or -7 VU asa “zero”.
Mixing
Program material must be in uncompressed form
for mixing and sound-on-sound recording. You
must first decode the program material which
has been encoded by the DX-2D in order to mix
it with any other material — compressed or un-
compressed. Of course, mixed material may be
compressed again for recording. If this precau-
tion is not followed, you'll get cross-modulation
of the separate signals or tracks.
The little guys in the box will look at their
“chart” and give you some really entertaining
level shifts, as we have said, they're fast but
dumb.
Subsonics and Interference
The DX-2D incorporates an effective bandpass
filter with -3 dB response at 20 Hz and 30 kHz.
This filter suppresses undesirable sub- and super-
sonic frequencies to keep them from introducing
errors into the encode or decode process. How-
ever, If rumble from trains or trucks is picked
up by your microphone and fed to the DX-2D —
filters are not perfect — modulation of the
program material during low level passages may
occur. This low frequency component will not
itself be passed through the recorder and so, will
not be present at reproduce for proper decoding.
If this low level decoding error is encountered,
and subsonics are suspected, we suggest the
addition of a suitable high pass filter ahead of
the DX-2D and after the mic preamplifier for
further attenuation of these subsonic frequencies.
14
M-30 RECORDING MIXER
15
The M-30, a multi-function recording mixer, not
only offers multi-microphone recordings, mixing
and equalization functions, but also offers the
possibility to draw out any desired signal
throughout sound processing, and the ability to
mixdown to obtain a master tape on a 2-track
tape deck.
We recommend the TASCAM M-30 RECORD-
ING MIXER as the ideal partner for the 32.
FEATURES
INPUT SECTION
e 8 mic inputs (6 low impedance balanced, and
2 high impedance unbalanced mic inputs
e 8 tape inputs
e 8 line inputs
e Mic/line/remix (tape) input selector
e Mic ATT (0/20/40)
e 2 band parametric equalizer (60 — 1.5 К,
1k — 10kHz plus 12.5 kHz shelving type
equalizer (+15 dB))
e Mute switches
e Direct out
e Cue out
e Accessory send/receive for each input
e Overload indicator for each input
e Buss assign buttons and pan pots
MASTER SECTION
e 4 main program mixing busses
e Buss input for each buss
e Accessory send/receive for each buss
e 4 buss out (line out)
e Monitor gain and pan controls for each pro-
gram buss
Master fader
Meter input selector (buss/monitor/submix)
e Stereo monitor headphones with volume con-
trol and input selector (monitor/submix)
SUBMIX SECTION
8 x 2 submixer
Pre/post/tape input selector
Gain and pan controls
Submix master gain control
Stereo submix out
Stereo submix in
OTHERS
e 2 setsof stereo phono in/out terminals (built-in
phono RIAA EQ)
SPECIFICATIONS
8-Input/4-Line Output/2-Monitor Output/2-Submix Output
Input Selector
1 — 6 channel:
7, 8 channel:
MIC (Low impedance)/
REMIX/LINE
MIC (High impedance)/
REMIX/LINE
Mic Input (Low impedance) — channel 1 — 6:
Mic impedance:
Input impedance:
Nominal input level:
Maximum input level:
200 to 600 ohms nominal mics
(matched for mics of 600 ohms
or less)
600 ohms, balanced XL.R type
-60 dBV (1 mV)
+10 dBV (3 V) — ATT to 40 dB
Mic Input (High impedance) — channel 7, 8:
Mic impedance;
Input impedance: .
Nominal input level:
Maximum input level:
Line Input
Input impedance:
Nominal input level:
Maximum input level:
Tape Input:
Input impedance;
Nominal input level:
Maximum input level:
Line Output:
Minimum load
impedance:
Nominal load
Impedance:
Nominal output level:
Maximum output level:
Monitor Output:
Minimum load
impedance:
Nominal load
impedance:
Nominal output level:
Maximum output level:
Submix Output:
Minimum load
impedance:
Nominal load
impedance:
Nominal output level:
Maximum output
level:
Cue Output:
Minimum load
impedance:
Nominal load
impedance:
Nominal output level:
Direct Output:
Minimum load
impedance:
Nominal load
impedance:
Nominal output level:
10k ohms nominal mics
100k ohms
-60 dBV (1 mV)
+10 dBV (3 V) — ATT to 40 dB
20k ohms
-10 dBYV (0.3 V)
+14 dBV (5 V)
50k ohms
-10 dBV (0.3 V)
+14 dBV (5 V)
БК ohms
10k ohms
-10 dBV (0.3 V)
+14 dBV (5 V)
bk ohms
10k ohms
-2.2 dBV (0.775 V)
+14 dBV (5 V)
hk ohms
10k ohms
-10 dBV (0.3 V)
+14 dBV (5 V)
Bk ohms
10k ohms
-10 dBV (0.3 V)
5k ohms
10k ohms
-10 dBV (0.3 V)
ACCESS SEND Output (Input/Master Section):
Minimum load
impedance:
Nominal load
impedance:
Nominal output level:
bk ohms
10k ohms
-10 dBV (0.3 V)
ACCESS Receive Input (Input/Master Section):
Input impedance:
Nominal input level:
Minimum input level:
200k ohms
-10dBV (0.3 V)
-18 dBV (0.13 V)
Submix input — channel L,R (and PRE, POST, TAPE 1 — 8):
Input impedance:
Nominal input level:
Maximum input level:
Buss Input
Input impedance:
Nominal input level:
Maximum input level:
Headphones Output:
Load impedance:
Maximum output
power:
Phono Input
Input impedance:
Nominal input level:
Minimum input level:
Maximum input level:
Phono Output:
Minimum load
impedance:
Nominal load
Impedance:
Nominal output level:
Frequency Responce:
Line output:
monitor output:
Submix output:
Equalizer:
Type:
Level:
Frequency, low:
Middle:
High:
10k ohms
-10 dBV (0.3 V)
+14 dBV (5 V)
10k ohms
-10 dBV (0.3 V)
+14 dBV (5 V)
8 ohms
Greater than 100 mW — Output
VR at max.
45k ohms
-54 dBV (2 mV) at 1 kHz
-60 dBV (1 mV) at 1 kHz
-30 dBV (31.6 mV} at 1 kHz
bk ohms
10k ohms
-10 dBV (0.3 V) at 1 kHz
30 to 20,000 Hz, +2 dB
30 to 20,000 Hz, +2 dB
30 to 20,000 Hz, +2 dB
Peak Parametric and Shelving
+15 dB
60 to 1,500 Hz
1,000 to 10,000 Hz
12,500 Hz
Signal to Noise Ratio (A weighted/unweighted)
Equivalent
Mic (Low impedance): 116 dB WTD
Mic (Low impedance)
1 channel: .
6 channel:
Mic (High impedance)
1 channel:
2 channel:
Mic (Low and high
impedance) 8 channel:
Phono input to
phono output:
Cross Talk:
Total Harmonic
Distortion:
Fader Attenuation:
Overload Indicator
Level:
Peak Indicator Level:
Dimensions (WxHxD):
Weight
Power Requirement
114 dB UNWTD (20 to 20,000 Hz)
Better than 66/64 dB
Better than 57/55 dB
Better than 58/57 dB
Better than 55/53 dB
Better than 53/51 dB
Better than 57 dB
UNWTD (20 to 20,000 Hz)
Better than 60 dB
{1 kHz, Nominal input level)
Less than 0.1 % at 1 kHz,
Nominal input level
60 dB or more
25 dB above nominal input level
10 dB above nominal output level
465 x 160 x 520 mm
(18-1/4"" x 6-5/16" x 20-1/2"")
16 kg (35-5/16 Ibs.)
100/120/220/240 V AC, 50/60 Hz,
26 W (General Export Model)
120 V AC, 60 Hz, 26 W
(U.S.A./Canada Model)
220 V AC, 50 Hz, 26 W
(Europe Model)
240 V AC, 50 Hz, 26 W
(UK/AUS Model)
16
ACCESSORY INFORMATION
TO-122A Test Tone Oscillator
Checks input/output balance or other electric
characteristics of the system chain. This unit is
also useful for tape deck maintenance work.
*Output pin jack
* Output level -10 dB, -40 dB (0 dB/1 V)
*Selectable frequencies 40 Hz, 400 Hz,
1 kHz, 4 kHz, 10 kHz,
15 kHz
E-3 Head Demagnetizer
E-2A Bulk Eraser
RE-1004 Reel (10-1/2”', 1/4” tape)
RE-712 Reel (77, 1/4” tape)
17
PB-64 Patch Bay
A tangle of cables is one of the growing vexations
of any audio system. With all of the inputs and
outputs plugged into the rear panel, jumper
cables plugged into the front make any hookup
you need neatly.
RC-71 Remote Control Unit
RC-30P Punch In/Out Remote Pedal
RM-300 Rack Mount Angle (EIA 19-inch)
The RM-300 is a rack mounting angle kit for the
TASCAM recorder/reproducer 32 to enable
mounting in the CS-607 or a standard 19-inch
rack.
CS-607 Console Rack (EIA 19-inch)
The CS-607 is a standard 19-inch console rack
to be used with the RM-300 for mounting of the
TASCAM 32.
T-0804 Blank Panel (EIA 19-inch)
The T-0804 is designed to cover up the unavoid-
able blank spaces on the TASCAM CS-607 or
equivalent EIA standard 19-inch rack.
Professional Low Loss Cable
There are vast differences in cable design and
performance, and those differences can make or
break an otherwise excellent sound system. When
you're investing in the kind of high quality audio
equipment represented by the TASCAM Studio
Series, it makes sense to use TASCAM profes-
sional audio cables. Anyone who's switched to
them will tell you they re worth every cent.
LOW CAPACITANCE
Our cables feature very low capacitance under
15 picofarads per foot, so they don't act as
high-frequency roll-off filters as do typical
cables of 100 or 300 pF/foot. In addition, our
cables use an ultra-high density bare-copper
braided shield (99 % coverage), so electrostatic
noise (buzz or hum) and RFI (CB or broadcast
signals) are kept out of your program.
Low capacitance is important, and so is con-
sistent capacitance; that is, you want the elec-
trical coupling of center conductor-to-shield to
remain the same throughout the cable, even if it
is sharply bent, crushed, flexed, or tugged. Should
the local cable capacitance change, noise and/or
signal losses often result. We utilize the unique
dielectric known as Datalene. This special
insulation keeps the stranded signal conductor
perfectly centered within the shield. Datalene is
about as flexible as foam core dielectrics but
far more resistant to extreme heat or cold,
and it has a “memory”, so it retains its shape
after flexing. Datalene also acts as a mechanical
shock absorber, guarding against external im-
pacts which, in other cables, might sever the
center conductors and cause intermittent contact.
When we join the connector to the cable, we
insert the cable's stranded center conductor all
the way into the pin and then fill the pin with
solder. The braid is wrapped and soldered a full
120° around the shell, not tacked at one spot,
so you get maximum shielding and strength.
18
SPECIFICATIONS OF THE 32
19
MECHANICAL
Tape:
Track Format:
Reel Size:
Tape Speeds:
Speed Accuracy: 1)
Wow and Flutter: 1)
15 ips
7-1/2 ips
Fast Wind Time:
Start Time:
Capstan Motor:
Reel Motors:
Head Configuration:
Tape Cue:
Motion Sensing:
Dimensions:
Weight:
ELECTRICAL
Input Selector:
Line Input:
Input impedance:
Maximum source impedance:
Nominal input level:
Maximum input level:
Mic Input:
Source impedance:
Input impedance:
Nominal input level:
Maximum input level:
Line Output:
Output impedance:
Minimum load impedance:
Nominal load impedance:
Nominal output level:
Maximum output level:
Headphone output:
Bias Frequency:
Equalization:
Record Level Calibration:
Frequency Response:
Record/Reproduce: 3)
15 ips
7-1/2 ips
Sync and Reproduce: 2)
15 ips
7-1/2 ips
Total Harmonic Distortion (THD) :3!
1/4 inch, 1-1/2 mil, low noise, high output tape
2-track, 2-channel, track width, NAB 0.079 inch (2.0 mm), DIN
2.7 mm
10-1/2"" NAB (large) hub maximum
15 inches per second (38 cm/sec.}, 7-1/2 inches per second (19 cm/sec.);
Variable, £12 % relative to 15 ips/7-1/2 ips
+0.8 % deviation
+0.06 % peak (DIN/IEC/ANSI weighted)
+0.1 % peak (DIN/IEC/ANS! unweighted)
0.05 % RMS (JIS/NAB weighted)
0.07 % RMS (JIS/NAB unweighted)
+0.09 % peak (DIN/IEC/ANSI weighted)
+0.12 % peak (DIN/IEC/ANSI unweighted)
0.07 % RMS (JIS/NAB weighted)
0.09 % RMS (JIS/NAB unweighted)
90 seconds for 10-1/2” reel 2,400 feet
Less than 0.8 sec. to reach standard Wow and Flutter
FG (frequency generator) DC servo motor
2-slotless DC motors
3 heads; erase, record/reproduce x 2
Manual
0.8 sec. 20.15 sec. delay time, stop to next motion
(W) 16-3/16" x (H) 18-3/16'” x (D) 10-1/8" (410 x 461 x 256 mm)
44.1 lbs (20 kg), net
Line/Mic/Mic ATT (20 dB)
50k ohms, unbalanced
2.5k ohms
-10 dBV (0.3 V)
+18 dBV (8.0 V)
10k ohms or less
10k ohms, unbalanced
-60 dBV (1 mV)
-3 dBV (700 mV), with mic ATT (20 dB) engaged.
1 k ohms, unbalanced
10 kohms
50 k ohms
-10 dBV (0.3 V)
+18 dB (8.0 V)
100 mW maximum at 8 ohms stereo headphones
150 kHz
NAB (USA/Canada/General Export models):
3180 + 50 usec. at 15 ips {38 cm/sec.), 7-1/2 ips (19 cm/sec.)
IEC-1 (Europe/U.K./Australia models):
œ + 35 usec. at 15 ips (38 cm/sec.), 9 + 70 usec. at 7-1/2 ips
(19 cm/sec.)
O VU reference; 250 nWb/m tape flux level
40 Hz — 22 kHz, +3 dB at O VU
40 Hz — 22 kHz, +3 dB at -10 VU
40 Hz — 16 kHz, +3 dB at O VU
40 Hz — 20 kHz, +3 dB at -10 VU
40 Hz — 22 kHz, +3 dB
40 Hz — 20 kHz, +3 dB
0.8 % at O VU, 1,000 Hz, 250 nWb/m
3 % at 13 dB above O VU, 1,000 Hz, 1,116 nWb/m
Signal-to-Noise Ratio:3)
15 ips
7-2/2 ips
Adjacent Channel Crosstalk (Overall) :3)
Erasure:3)
Headroom:
Connectors:
Line inputs and outputs:
Mic input:
Remote control:
Punch in/out remote:
dbx unit:
Power Requirement:
At a reference of 1 kHz, at 13 dB above 0 VU, 1,116 nWb/m
68 dB A weighted (NAB), 60 dB unweighted
66 dB A weighted (NAB), 58 dB unweighted
92 dB A weighted (NAB), with dbx™
82 dB unweighted, with dbx
Better than 50 dB down at 1,000 Hz, 0 VU
Better than 65 dB at 1 kHz, +10 VU reference
Recording Amplifier — Better than 25 dB above 0 VU at 1 kHz
RCA jack
Phone jack (Tip-Sleeve)
Multi-Pin jack
Phone jack (Tip-Sleeve)
Multi-Pin jack
100/120/220/240 V AC, 50/60 Hz, 70 W (General Export Model)
120 V AC, 60 Hz, 70 W (USA/Canada Model)
220 V AC, 50 Hz, 70 W (Europe Model)
240 V AC, 50 Hz, 70 W (UK/AUS Model)
In these specifications, O dBV is referenced to 1.0 Volt. Actual voltage levels also are given in parenthesis.
To calculate the 0 dB = 0.775 Volt reference level (i.e., 0 dBm in a 600-ohm circuit) add 2.2 dB to the
listed dB value; i.e., -10 dB re: 1 V = -7.8 dB re: 0.775 V.
1) Specifications were determined using TEAC Test Tape YTT-2004/YTT-2003.
2) Specifications were determined using TEAC Test Tape YTT-1004/YTT-1003 (NAB Equalization), YTT-1044/
YTT-10432 (IEC Equalization)
3) Specifications were determined using TEAC Test Tape YTT-8063.
Changes in specifications and features may be made without notice obligation.
*dbx is a trademarks of dbx Inc.
Options for:
Mounting (Standard 19 inch rack):
Remote control:
Punch in/out remote control:
543 mm {21-7/16"")
RM-300 Rack Mount Angle, CS-607 Console Rack and T-0804 Biank Panel
Full transport function available with RC-71
Punch in/out function available with RC-30P
256 mm (10-1/8")
410 mm {16-3/16")
170 mm (6-3/4”)
461 mm (18-3/16"")
522.5 mm {20-5/8"}
444 mm (17-1/2”)
En np 6h =
©
|
20
THE dB; WHO, WHAT, WHY
No matter what happens to the signal while it is
being processed, it will eventually be heard once
again by a human ear. So the process of con-
verting a sound to an electrical quantity and
back to sound again must follow the logic of
human hearing.
The first group of scientists and engineers to
deal with the problems of understanding how
the ear works were telephone company
researchers, and the results of their investigations
form the foundation of all the measurement
systems we use in audio today. The folks at Bell
Laboratories get the credit for finding out how
we judge sound power, how quiet a sound an
average person can hear, and almost all of the
many other details about sound you must know
before you can work with it successfully.
From this basic research, Bell Labs developed a
system of units that could be applied to all
phases of the system. Sound traveling on wires
as electrical energy, sound on tape as magnetic
energy, sound in air; anyplace that sound is, or
has been stored as energy until some future
time when it will again be sound, can be
described by using the human ear-related system
of numbers called ‘‘bels” named in honor of
Alexander Graham Bell, the inventor of the tele-
phone.
What is a bel and what does it stand for?
It means, very simply, twice as loud to the
human ear. Twice as loud as what? An obvious
question. The bel is always a comparison
between two things. No matter what system
of units of measure you are working with at
the time, you must always state a value as a
reference before you can compare another value
to it by using bels, Volts, dynes, Webers — it
doesn't matter, a bel, or ear-related statement of
“twice as loud” is always a ratio, not an absolute
number. Unless a zero, or “no difference” point
is placed somewhere, no comparison is possible.
There are many positive and definite statements
of reference in use today. But before we go over
them, we should divide the “bel” into smaller
units. “Twice as loud” will be a little crude to
be used all the time. How about one tenth of a
bel? Okay, the decibel it is, and O means “no
difference, same as the reference”. It seldom
means “nothing”. Now, if you double the
power, is that twice as loud? No, it is only 3 dB
more sound. If you double an electrical voltage,
is it twice as loud? No, it is only 6 dB more
sound. The unit quantities must follow nonlinear
21
progressions to satisfy the ears’ demand.
Remember, decibels follow the ears. All other
quantities of measure must be increased in
whatever units necessary to satisfy the human
requirements, and may not be easy to visualize.
Sound in air, our beginning reference, is the least
sound the human ear (young men) can detect at
1000 to 4000 Hertz. Bell Labs measured this
value to be .0002 microbar, so we say 0 dB =
.0002 microbar and work our way up from the
bottom, or from the point at which there is “no
perceivable sound to humans”. Here is a chart of
sounds and their ratings in dB, using .0002
microbar pressure change in air as our reference
for “0 dB sp!” (Sound Pressure Level).
SOUND AND MUSIC REFERENCE
1,013,000 104 dbspl
microbars
100,000
microbars 170
—— 160
22 inch bass drum
10,000 | mic inside drum
microbars —$— 150
Snare drum
1 inch
—t— 140 Operatic voice
at 1 inch (scream)
1,000 dynes per 1000 _1_
square cm. micobars ——130 Symphony orchestra
triple forte at 30 feet
— 129 4 trumpets
at § ft. {fff)
10 newtons per 100 dynes per 100 *
square meter square cm. microbars "T- .
— 110, X Electric guitar amp at
. Piano, 4 ft. 6 inches at max. volume
+
Pa
—-100
1 newton per 10 dynes per 10 : .
square meter square cm. microbars J dbspl З\ 1” Average speech at 1/2 inch
Acoustic guitar
played with a pick
Acoustic guitar played
-—d— 80 with the fingers
. * \
: .
0.1 newton per 1 dyne per . — re A — Avera e conversation
square meter square cm, | 1 Microbar ] [74 bse! 1 2at6 feet
a »
—j— 60
AN Home in city, continuous background
0.1 microbar | : noise (cars subways, street noise)
—t— 50 . 2, .
—————— Home in city at night
*
*
—— 40
0.01 microbar ——
—— 30
— —— — ——— isolated recording or TY studio
—— 20
o Open field, night, no wind
0.001 microbar +. {crickets, insect noises, etc.)
0.0002 microbar 0 dbspl = Q sound pressure level (threshoid of hearing!
Since the reference is assumed to be the lowest
possible audible value, dB spl (Sound Pressure
Level) is almost always positive, and correctly
written should have a + sign in front of the
number. But it is frequently omitted. Negative
dB spl would indicate so low an energy value
as to be of interest to a scientist trying to record
one cricket at 1,000 yds. distance, and is of no
significance to the multichannel recordist. Far
more to the point is the question “What is а
microbar?” lt is a unit of measurement related
to atmospheric pressure and although it is
extremely small, it must be divided down quite
a lot before it will indicate the minimum
pressure change in air that we consider minimum
audible sound. This will give you a better idea of
the sensitivity of the human ear.
One whole atmosphere, 14.70 pounds per
square inch, equals 1.01325 bars. So one whole
atmosphere in microbars comes out to be
1,013,250. One microbar of pressure change is
slightly less than one millionth of an atmosphere,
and you can find it on our chart as 74 dB spl.
It is not terribly loud, but it is certainly not hard
to hear. As a matter of fact, it represents the
average power of conversational speech at 6 feet.
This level is also used by the phone company to
define normal earpiece volume on a standard
telephone. Now think about that minimum
audible threshold again:
.0002 microbar.
That's two ten-thousandths of a millionth part
of one atmosphere!
This breakdown of one reference is not given
just to amaze you, or even to provide a feel for
the quantity of power that moderate levels of
sound represent. Rather, it is intended to
explain the reason we are saddled with a ratio/
logarithm measurement system for audio.
Adding and subtracting multi-digit numbers
might be easy in this age of pocket calculators,
but in the 1920's when the phone company
began its research into sound and the human
ear, a more easily-handled system of numbers
became an absolute necessity. Convenience for
the scientist and practical engineer, however, has
left us with a system that requires a great deal
of complex explanation before you can read and
correctly interpret a “spec sheet” for almost any
piece of gear.
Here are the formulae for unit increment; but
they are necessary only for designers, and unless
you build your own gear, you won't have to deal
with them. For power (watts) increase or loss,
calculate by the following equation:
10 LOG ‚opt = N (dB)
For voltage, current or pressure calculations:
20 LOG, Ме N (dB)
Plotting the points resultant from using these
equations we come up with the following chart.
Once we have this chart, we can see the
difference between the way humans perceive
sound and the amount of force it takes to
change air pressure. Unfortunately, the result is
not a simple “twice as much pressure” of sound
to be heard as “twice as loud”. If you plot
decibels as the even divisions on a graph, the
unit increase you need is a very funny curve.
VOLTAGE, CURRENT OR PRESSURE >
„м2
dB = 20 |
. og vi
vz |
vi |
Must rise this way
Rise in even 1 dB Unit
Increase
This is how the ear works, and we must adapt
our system to it. We have no choice if we
expect our loudspeaker to produce a sound that
resembles the original sound we begin with. The
high sensitivity to sound of the human ear
produces a strong “energy” illusion that has
confused listeners since early times. How
powerful are the loudest sounds of music in real
power? Can sound be used as a source of energy
to do useful work, such as operating a car? For
22
any normally “loud” sound the answer is,
regrettably, no! perhaps not so regrettably,
consider what would happen if one pound of
pressure was applied not to your head, but
directly to your inner ear. One pound of air
pressure variation is 170 dB spl! This amount of
“power” might do some useful work — but not
much, it’s still only one pound and to make use
of it you will have to stand one mile away or
you will go deaf immediately.
If we reduce our sound power to realistic
musical values, we will not be injured, but we
Will have almost nothing. (in real power terms) to
run the mic with!
This low available energy is the reason that high
gain amplifiers are required for microphones.
When we take a microphone and “pick up” the
sound, we do have some leeway in deciding how
much energy we must have in order to operate
the electrical part of our system. If we can
decide that we don't have to truly hear the
signal while we are processing it from point to
point and we can wait until the electronic
devices have done all their routing and switching
before we need audible sound, we can lower the
power of the signal. What is a good value for a
reference here? Well, we need to have enough
energy so that the signal is not obscured by hiss,
hum, buzz or other unpleasant things we don't
want, but not so high that it costs a fortune in
“Juice” or electrical power. This was a big
consideration for the telephone company.
They now have the world's biggest audio mixing
system, and even when they started out, elec-
tricity was not free. They set their electrical
power signal reference as low as was practical at
the time, and it has lowered over the years as
electronic equipment has gotten better. In 1939
the telephone company, radio broadcasting, and
recording industry got together and standardized
1 milliwatt of power as O dBm, and this is still
the standard of related industries. Thus, a 0 dBm
signal into a 600 ohm-line impedance will
present a voltage of 0.775 volts.
Once again, we owe you an explanation. Why
does it say ZERO on the meter? What is an
ohm? Why 600 of them and not some other
value? What's a volt? Let's look at one thing at
a time.
1. The logic of ZERO on the meter is another
hangover from the telephone company
practice. When you start a phone call in
California, the significant information to a
23
telephone company technician in Boston is —
did the signal level drop? If so, how much?
When the meter says ZERO it indicates (to
the phone company) that there has been no
loss in the transmission, and all is well. The
reference level is one milliwatt of power, but
the gain or loss is in the information the
meter was supposed to display, so the logic of
ZERO made good sense, and that's what they
put on the dial. We still use it even though it’s
not logical for anything else, and the idea of a
reference level described as a “no loss”
ZERO, no matter what actual power is being
measured, is so firmly set in the minds of
everyone in the audio world that it 15
probably never going to change.
.One ohm is a unit of resistance to the passage
of electrical energy. The exact reasons for
the choice of 600 ohms as a standard are
connected to the demands of the circuits used
for long distance transmission and are not
simpie or easy to explain. Suffice it to say
that the worst possible thing you can do to a
piece of electronic equipment is to lower the
resistance it is expected to work into (the
load). The lower the number of ohms, the
harder it is to design a stable circuit. When
you think about “load”, the truth is just the
opposite of what you might expect! O ohms
is a “short circuit”, not resistance to the
passage of signal. If this condition occurs
before your signal gets from California to
Boston, you wont be able to talk — the
circuit didn't “get there”, it “shorted out”.
Once again, telephone company logic has
entered the language on a permanent basis.
Unless the value for ohms is infinity (no
contact, no possible energy flow) you will be
better off the higher the value, and many
working electronic devices have input
numbers in the millions or billions of ohms.
. A volt is a unit of electrical pressure, and by
itself is not enough to describe the electrical
power available. To give you an analogy that
may help, you can think of water in a hose.
The pressure is not the amount of water, and
fast flow will depend upon the size of the
hose (impedance or resistance} as well.
Increase the size of the pipe (lower the
resistance, or Z) and pressure (volts) will drop
unless you make more water (current)
available to keep up the demand. This analogy
works fairly well for DC current and voltage,
but alternating current asks you to imagine
the water running in and out of the nozzle at
whatever frequency your “circuit” is working
at, and is harder to use as a mental aid. Water
has never been known to flow out of a pipe at
10,000 cycles per second.
This reference level for a starting point has been
used by radio, television, and many other groups
in audio because the telephone company was the
largest buyer for audio equipment. Most of the
companies that built the gear started out
working for the phone company and new audio
industries, as they came along, found it eco-
nomical to use as many off-the-shelf components
as they could, even though they were not
routing signals from one end of the world to the
other.
Must we use this telephone standard for record-
ing? Its usein audio has been so widespread that
many people have assumed that it was the only
choice for quality audio. Not so.
A 600-ohm, 3-wire transformer-isolated circuit
is a necessity for the telephone company, but
the primary reason it is used has nothing to do
with audio quality. It is noise, hum and buzz
rejection in really long line operation (hundreds
and hundreds of miles).
Quality audio does not demand 600-ohm, 3-wire
circuitry. In fact, when shielding and isolation
are not the major consideration, there are big
advantages in using the 2-wire system that go
well beyond cost reduction. It is, as a system,
inherently capable of much better performance
than 3-wire transformer-isolated circuits.
Since TASCAM's mixers are designed to route
a signal from a mic to a recorder, we think
that the 2-wire system is a wise choice. The
internationally accepted standard (IEC) for
electronics of this kind uses a voltage reference
without specifying the exact load it is expected
to drive. The reference is this:
O dB = 1 Volt
This is now the preferred reference for all
electronic work except for the telephone
company and some parts of the radio and
television business. Long distance electronic
transmission still requires the 600-ohm standard.
If your test gear has a provision for inserting a
600-ohm load, be sure the load is not used when
working on TASCAM equipment.
Now that we have given a reference for our
“0 dB” point, we can print the funny curve
again, with numbers on it, and you can read
voltages to go along with the changes in dB.
3.16V 10V
316 units 1000units
4
1.5\
/
1V , 1 V2 ¡100 units
0 log vi curve |
|
0.5V |
: 0.316V !
(3.16 units |
...0.1V !
0.01V 1units 31.6units 1 10units |
0
-40 -30 -20 -10
|
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pa ны
1
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+10 +20
OdB = 1V
24
IMPEDANCE MATCHING AND LINE LEVELS
All electronic parts, including cables and non-
powered devices (mics, passive maxiers and
such), have impedance, measurable in ohms
(symbol © ог 2). Impedance is the total
opposition a part presents to the flow of signal,
and it's important to understand some things /
about this value when you are making con-
nections in your mixing system. The outputs of
circuits have an impedance rating and so do
inputs. What's good? What values are best? It
depends on the direction of signal flow, and in
theory, it looks like this:
Plug into
OUTPUTS
It is generally said that the output imped-
ance (7) should be as low as possible.
100 ohms, 10 ohms. The lower, the better,
in theory. A circuit with a low output
impedance will offer a low resistance to the
passage of signal, and thus will be able to
supply many multiple connections without
a loss in performance or a voltage drop in
any part of the total signal pathway. Low
impedance values can be achieved econom-
ically by using transistors and integrated
circuits, but other considerations are stili a
problem in practice.
1. The practical power supply is not
infinitely large. At some point, even if
the circuit is capable of supplying more
energy you will run out of “juice”.
2. Long before this happens, you may burn
out other parts of the circuit. The
output impedance may be close to the
theoretically ideal ‘ohms’ but many
parts in the practical circuit are not.
Passing energy through a resistance
generates heat and too much current will
literally burn parts right off the circuit
board if steps are not taken to prevent
catastrophic failure.
3. Even if the circuit does not destroy
itself, too high a demand for current
may seriously affect the quality of the
audio. Distortion will rise, frequency
response will suffer, and you will get
poor results.
> INPUTS
Inputs should have very high impedance
numbers, as high as possible (100,000
ohms, 1 million ohms, more, if it can be
arranged). A high resistance to the flow of
signal at first sounds bad, but you are not
going to build the gear. If the designer tells
you his input will work properly and has
no need for a large amount of signal, you
can assume that he means what he says.
For you, a high input impedance is a
virtue. It means that the circuit will
do its job with a minimum of electrical
energy at the beginning. The most “eco-
nomical’’ electronic devices in use today
have input impedances of many miilions of
ohms. Test gear, for example, voltmeters of
good quality must not draw signal away
from what they are measuring, or they will
disturb the proper operation of the circuit.
A design engineer needs to see what is
going on in his design without destroying
it, so he must have an “efficient” device to
measure with.
Plugs into
SOURCE (output)
The classic procedure for measuring output
impedance is to reduce the load's impedance
until the output voltage drops 6 dB (half the
original power) and note what the load value is.
In theory, you now have a load impedance that
is equal to the output impedance. If you
gradually reduce the load (increase the input
impedance), the dB reading will return slowly to
its original value. How much drop is acceptable?
What load will be left when an acceptable drop
is read on the meter? /
25
» LOAD (input)
Traditionally, when the load value (input Z) is
approximately seven times the output imped-
ance, the needle is still a little more than 1 dB
lower than the original reading.
Most technicians say, “1 dB, not bad, that's
acceptable.” We at TASCAM must say that we
do not agree. We think that a seven-to-one ratio
of input (7) to output (1) is not a high enough
ratio, and here's why:
1. The measurement is usually made at a mid-
range frequency and does not show true loss
at the frequency extremes. What about the
drop at 20 Hz or 30 kHz?
2. All outputs are not measured at the same
time. Most people don't have twenty meters,
we do. Remember, everybody plays together
when you record and the circuit demands, in
practice, are simultaneous. All draw power at
the same time.
Because of the widely misunderstood rule of
thumb — the seven-to-one ratio — we will give
you the value for output impedance.
True Output Impedance
Even though the true output impedance may be
low, say 100 ohms, it takes a lab to check the
rule of thumb, so for the practical reasons we
have explained, the use of the ratio method of
‘impedance calculation must be changed to a
higher ratio. We prefer 100:1 if possible and we
consider 50:1 to be the minimum ratio that we
think safe. Because of this, we will give you a
number for ohms that you can match, Minimum
Load Impedance. No calculations, we have made
them already.
Minimum Load Impedance
MAKE CERTAIN THAT YOU CONNECT NO
TOTAL LOAD IMPEDANCE LOWER (nu-
merically) THAN THIS FIGURE.
LINE OUTPUT: 10k ohms
Nominal Load Impedance
Our specifications usually show 10,000 ohms as
a Nominal Load Impedance. This load will
assure optimum performance. Remember, any
Impedance lower than 10,000 ohms is more
load.
Input Impedance
Input impedance is more straight forward and
requires only one number. Here are the values
for the 32.
LINE INPUT: 50k ohms
MIC INPUT: 10k ohms
If one output is to be “Y” connected to two in-
puts the total impedance of the two inputs must
not be lower than the minimum load impedance,
mentioned above, and if it becomes necessary to
increase the number of inputs with slight reduc-
tion of the load specifications, you must check
for a drop in level, a loss of headroom, low
frequency response, or else suffer from a bad
recording. If one input is 10,000 ohms, another
of the same 10,000 ohms will give you a total
input impedance (load) of 5,000 ohms. To avoid
calculations you can do the following when you
have two inputs to connect to one output.
Take the lower value of the two input imped-
ance and divide it in half. If the number you
have is greater than the minimum load imped-
ance, you can connect both at the same time.
Remember, we are not using the true output im-
pedance we are using the adjusted number, the
minimum output load impedance.
If you must have exact values here is the formula
for dissimilar 2 loads or inputs:
Вх = R1 x R2
R1 + R2
When you have more than two loads (inputs),
just dividing the lowest impedance by the num-
ber of inputs will not be accurate unless they are
all the same size. But if you still get a number that
is higher than the minimum load impedance by
this method, you can connect without worry.
If you must have exact values, here is the formula
for more than 2 loads or inputs:
Rx =
010 1
RR2*
Rx = Value of Total Load
Finding Impedance Values on Other Brands of
Equipment
When you are reading an output impedance spe-
cification, you will occasionally see this kind of
statement
Minimum load impedance = x ohms
or
Maximum load impedance = x ohms
These two statements are trying to say the same
thing, and can be very confusing. The minimum
load impedance says: please don’t make the
NUMBER of ohms you connect to this output
any lower than x ohms. That's the lowest NUM-
BER. The second statement changes the logic,
but says the exact same thing.
26
Maximum load impedance refers to the idea of
the LOAD instead of the number, and says:
please don’t make the LOAD any heavier. How
do you increase the load? Make the number
lower for ohms. Maximum load means minimum
ohms, so read carefully.
When the minimum/maximum statement is
made, you can safely assume that the manufac-
turer has already done his calculations, and the
number given in ohms does not have to be
multiplied. You can MATCH the value of your
input to this number of ohms successfully; but
as always, higher ohms will be okay (less load).
Occasionally, a manufacturer will want to show
you that / times the output Z is not quite the
right idea and will give the output impedance
and the correct load this way, they will call the
output impedance the True Output Impedance
and then will give the recommended minimum
LOAD impedance. It may be a higher or lower
ratio than 7 times and will be whatever the spe-
cific circuit in question requires.
27
REFERENCE LEVELS
We should talk about one more reference, a
practical one.
Anyone who has ever watched a VU meter
bounce around while recording knows that “real
sound” is not a fixed value of energy. It varies
with time and can range from “no reading” to
“good grief” in less time than it takes to blink.
In order to give you the numbers for gain, head-
room and noise in our mixers, we must use a
steady signal that will not jump around. We use
a tone of 1000 Hz and start it out at a level of
-60 dB at the mic input, our beginning reference
level. All levels after the mic input wili be higher
than this, showing that they have been amplified,
and eventually we will come to the last output
of the mixer — the line-out and the reference
signal there will be -10 dB, our “line level” re-
ference.
From this you can see that if your sound is
louder than 94 dB spl — your mic will produce
more electricity from a sound of 94 dB spl than
-60 dB, all these numbers will be changed. We
have set this reference for mic level fairly low. If
you examine the sound power or sound pressure
level (spl) charton page 21 you will see that most
musical instruments are louder on the average
than 94 dB spl, and most commercial mics will
produce more electricity than the -60 dB for a
sound pressure of 94 dB, so you should have no
problems getting up to “0 VU” or your recorder. _
We should also make a point of mentioning that
the maximum number on the charton page 21re-
presents “peak power” and not average power.
The reason? Consider if even some momentary
part of your recording is distorted, it will force a
re-recording and it is wisest to be prepared for
the highest values and pressure even if they
only happen “once in a while”, On this point,
statistics are not going to be useful, the average
sound pressure is not the whole story. The
words themselves can be used as an example.
Say the word “statistics” close to the mic while
watching the meters and the peak LED level
detector. Then say the word “average”. What
you are likely to see are two good examples of
the problems encountered in the “real world”
of recording. The strong peaks in the “s” and
“t” sounds will probably cause the LED's to
flash long before the VU meter reads anywhere
near “zero” while the vowel sounds that make
up the word “average” will cause no such
drastic action.
To allow peaks to pass undistorted through
a chain of audio parts, the individual gain
stages must all have a large reserve capability.
If the average is X, then X +20 dB is usually safe
for speech, but extremely percussive sounds
may require as much as 40 dB of “reserve” to
insure good results. Woodblocks, castanets, latin
percussion (guido, afuche) are good examples of
this short term violence that will show a large
difference between “LED flash” and actual
meter movement. When you are dealing with
this kind of sound, believe the LED, it is telling
you the truth.
If you are going to record very loud sounds you
may produce more electrical power from the
mic than the mixer can handle as an input. How
can you estimate this in advance? Weli, the spl
chart and the mic sensitivity are tied together on
a one-to-one basis. If 94 dB spl in gives -60 dB
(1 mV) out, 104 dB spl will give you -50 dB out,
and so forth. Use the number, on our chart for
sound power together with your mic sensitivity
ratings to find out how much level, then check
that against the maximum input levels for the
various jacks on your mixer. |f your mic is in
fact producing -10 dB or line level, there is
nothing wrong with plugging it into the line-level
connections on the mixer. You will need an
adaptor, but after that it will work!
Most mic manufacturers give the output of their
mics as a minus-so-many-dB number, but they
don’t give the loudness of the test sound in dB,
It's stated as a pressure reference (usually 10
microbars of pressure). This reference can be
found on our sound chart. It is 94 dB spl, 10
microbars, 10 dynes per cm? or 1 Newton per
square meter. For mics, the reference “0” is
1 volt (dB). So, if the sound is 94 dB spl the
electrical output of the mic is given as -60 dB,
meaning so many dB less than the reference O =
1 volt. In practice you will see levels of -60 dB
for low level dynamics, up to about -40 dB or
slightly higher for the better grade of condenser
mics available today. TASCAM recorders and
mixers work at a level of -10 dB referenced to
1 volt (.316 volt) so, for 94 dB spl, a mic with a
reference output of -60 dB will need 50 dB of
amplification from your mixer or recorder
in order to see ‘’O VU”’ (-10 dB) on your meter.
Now, if the sound you want to record is louder
than 94 dB spl, the output from the mic wili be
more powerful and you will need less amplifica-
tion from your mixer to make the needles on
your recorder read “0 VU”.
28
CALIBRATION
NOTE:
Peak meters may vary considerably in the values
which are equivalent to O VU. If any of the
equivalent in your system uses peak meters,
make sure you match your peak meter levels to
correspond to O VU; do not automatically
assume a direct correlation between the read-
ings on the two different types of meters.
“Calibration” simply means matching all the
reference levels in your recording system to
ensure that signals from one element in the
system are equally interpreted by all the other
elements in the system.
If youre really serious about making true
professional-quality recordings, then a reliable
tone generator is a necessity in order to ac-
curately calibrate your system. We recommend
the TEAC TO-122A test-tone oscillator. When
using a tone generator, select a signal that will
be equivalent to 0 VU when passed through the
device to which you are calibrating the 32 . For
example, if you are using a mixer with O dB
referenced to 1 V (TASCAM mixers and re-
corders all use this reference level) and the mic
input level is -60 dB and the line level (both
input and output) is -10 dB, then, with the
mixer's faders set to the shaded area, a 1 mV
signal fed through the mic input or a 316 MV
signal fed through the line input can be used to.
precisely establish the O VU level on the mixer.
In this case (as with TASCAM line), -10 dB
corresponds to O VU. If the equipment you
are using references O dB to .775 V rather than
1 V, then a correction factor of 2.2 dB will have
to be used to compensate for the diference.
The frequency of the tone used as the calibra-
tion signal has little effect on calibration, so any
reasonable frequency may be used (400 Hz or
1 kHz is recommended). If you wish to calibrate
your system without a tone generator, any
source that produces a sustained tone, such as a
musical instrument or even a vacuum cleaner,
can be used to generate a reference signal;
however, since there is no way to measure the
reference level of such signal, experimentation
with microphone placement and/or different
volumes will be required to establish a reason-
able recording reference level.
To calibrate, use a sustained tone and set the
controls on your mixer and/or multitrack
recorder so that their VU meters read 0 VU,
and, passing the signal through the multitrack
29
recorder and/or mixer, set the controls on the
32 so that its VU meters also read 0 VU. After
calibrating your system, make all subsequent
level adjustments from the mixer or the first
unit receiving input in the recording chain;
do not change the controls on the rest of your
equipment.
When using an oscillator for system calibration,
start with a frequency setting somewhere
midpoint in the audio range. This ensure that
frequency limitations of metering circuitry will
not affect accuracy. The audio range is three
decades wide so choose a frequency typically
in the 200 to 2,000 Hz area of the audio range.
All TASCAM mixers and recorders use the [EC
standard, 1 V = 0 dB or O dBV, as the reference
to which all measurements are made. The input
level (and output level) that TASCAM gear uses
as its O VU reference, is -10 dBV, or 0.316 V.
If any of the gears you use have a different
reference (eg. O = .775 V/600 ohms) then use
the appropriate correction factor as follows:
Different correction factors:
О аВт = 0.775 V/
600 ©
0 dBu = 0.775 V/
higher than 600 Q
O0 dBV = 1 V | Voltage
+6 dB 2V +8.2 dB
+1.78 dB 1.228 V +4 dB
0.5 V -3.8 dB
Note:
1. The “u” in “0 dBu” stands for “unbalanced”.
2. Peak meters read 3 dB or so higher than RMS or
VU meters, so when calibrating your system make
sure that any peak meters are reading properly to
compensate the difference.
MORE INFORMATION IS AVAILABLE
We've tried to give you representative examples
of some of the things you can do to get started,
and you'll discover many more — some by way
of happy coincidence, others after long hours of
concentration. If you're just getting into record-
ing and want to expand your knowledge, more
information is available.
BIBLIOGRAPHY
Beranek, Leo L.
ACOUSTICS
McGraw-Hill Book Co. Inc.
New York, New York
1954
More concerned with exact formulae, but still very readable. It is
not necessary to do calculations to gain knowledge from this
textbook.
Beranek, Leo L.
MUSIC, ACOUSTICS AND ARCHITECTURE
John Wiley & Sons, Inc.
New York, N.Y.
1962
A technical survey on concert halls with much documentation.
Worth reading, this author has many useful stories to tell about
the interface of science and art.
Clifford, Martin
MICROPHONES: HOW THEY WORK AND HOW TO USE
THEM
Tab Books
Blue Ridge Summit, Pa.
1977
An excellent low cost book for the beginner on microphone
types, history and construction. The explanations given assume
no prior knowledge and are very complete. Recommended.
Everest F. Alton
ACOUSTIC TECHNIQUES FOR HOME AND STUDIO (3rd.
Printing)
Tab Books
Blue Ridge Summit, Pa.
1978
Low cost basic book. This book on studio acoustics is the easiest
to read and understand of all the textbooks on the subject, and
comes closest to dealing with the actual problems encountered in
the home studio.
Everest F. Alton
HANDBOOK OF MULTICHANNEL RECORDING
Tab Books
Blue Ridge Summit, Pa.
1976
A survey volume containing good information on all topics. Very
clearly written and recommended for a beginner.
Nisbett, Alec
THE TECHNICS OF THE SOUND STUDIO FOR RADIO,
TELEVISION AND FILM
Hastings House Publishers, Inc.
New York, N.Y.
1976
Although not specifically written for the tape recordist, this 500
page book is well worth its cost. Very useful practical advice if
you are working with speech (drama, commercial announcing,
etc.)
Nisbett, Alec
THE USE OF MICROPHONES
Hastings House
New York, N.Y.
1976
The authors point of view is basically radio, but has ability to
communicate difficult concepts is very good. Well illustrated.
Olsen, Harry F.
ACOUSTICAL ENGINEERING
D. Van Nostrand Company
New York, N.Y.
1957
and
Olsen, Harry F.
MUSICAL ENGINEERING
D. Van Nostrand Company
New York, N.Y.
1959
Anything you can find by this writer is worthwhile, and the
latter book in particular will give scientific answers to questions
(what frequency is the note DP above middle C?) and can be
used to translate one “language” into another. Extremely
valuable.
Rettinger, Michael
ACOUSTIC DESIGN AND NOISE CONTROL, VOL. 1
Chemical Publishing Company
New York, N.Y.
1977
Although this book is highly technical, the writing is very lucid
and many examples are given to go along with the math. This
writer is not afraid to draw conclusions and give his reasons for
doing so in simple language.
Runstein, Robert E.
MODERN RECORDING TECHNIQUES
Howard W. Sams and Co.
Indianapolis, Indiana
1974
The first low cost book on studio practice. The equipment dealt
with is somewhat outdated, but the theory is still the same.
Excellent basic survey.
Tremaine, Howard M.
THE AUDIO CYCLOPEDIA
Howard W. Sams and Co.
Indianapolis, Indiana
1976
This 1,700 page reference work is sure to contain the answer to
almost any technical question you can think of. The writing
assumes much prior knowledge and this book should be used
with others that are more basic in their writing style if you are
new to the field of scientific audio.
SOME MAGAZINES OF INTEREST:
“db” — THE SOUND ENGINEERING MAGAZINE
1120 Old Country Road
Plainview, N.Y. 11803
“MODERN RECORDING"
14 Vanderventer Avenue
Port Washington, N.Y. 11050
“RE/P” — RECORDING ENGINEER/PRODUCER
1850 Whitley Street, Suite 220
Hollywood, Ca. 90028
30
THEORY OF OPERAION—MAINTENANCE
If you are new to high quality sound recording
equipment, you should become aware of the
fact that high quality sound requires high
quality maintenance.
Recording studios that rent time by the hour
are very fussy about maintaining their equip-
ment. Tape recorders and other electronic
gear in the studio are checked out before every
session. And, if necessary, adjusted to “spec”
by an ‘in house’’ service technician. He is
usually prepared to correct any problem from
a minor shift in circuit performance to major
breakdown in a motor. He has a full stock
of spare parts and all the test equipment he
needs.
Now that you are running your own “studio”
you will have to make some decisions about
maintaining it, and your 32. You will have
to become your own “in house” service
technician. Well, what about the test gear
and the spare parts? A stock of spare parts
and a super deluxe electronic test bench can
easily cost many times the price of the re-
corder. Fortunately, the most frequently
needed adjustments use the least expensive
equipment, and the very costly devices are
only needed for major parts replacements
such as drive and rewind motors or head assem-
blies. Replacing parts cannot be considered
“daily maintenance” by any means, so we
suggest that you leave the major mechanical
and electrical repair to the Dealer Service
Center. That's what it's for.
31
Adjustments to the motors — back tension
and brake torque are not required often and
can safely be left to dealer service. The adjust-
ments for wow and flutter require several
thousands of dollars of test gear to perform.
lts not practical to consider doing these
adjustments yourself unless you have fifty
machines to service. Then it might pay to
buy the test gear.
In order to help you make plans about the
more routine adjustments to your 32, we
have made this section of the manual as easy to
understand as technology will allow. It's a short
course in tape recorder theory as well as a list of
adjustments and will help you to understand
what is going on inside when you record. Read
the manual, decide what test equipment you
can afford (although it is not violently ex-
pensive, it is not free) and determine what
service you can do yourself.
CLEANING
IMPORTANT:
Do not overlook the importance of cleaning.
Insufficent cleaning is the number one cause of
the degradation of performance levels.
The first thing you will need for service is
definitely the least expensive — Cleaning fluids
and swabs. The whole outfit, 2 fluids and all
the cotton swabs you'll need for months cost
less than one roll of high quality tape. We
can't stress the importance of cleaning too
much. Clean up before every session. Clean
up after every session. Clean up every
time you take a break in the middle of a
session (were serious). How come? Well
there are two good reasons we can think of
right off the top:
1. Any dirt or oxide buildup on the heads
will force the tape away from the gaps that
record and playback. This will drastically
affect the response. Even so small a layer
of dirt as one thousandth of an inch will
cause big trouble. All the money you have
paid for high performance will be wiped out
by a bit of oxide. Wipe it off with head
cleaner and get back to normal.
2. Tape and tape oxide act very much the
same as fine sandpaper. The combination
will grind down the tape path in time. If
you don’t clean off this abrasive on a regular
basis, the wear will be much more rapid and,
what's worse, 1t will become irregular. Even
wear on heads can be compensated for by
electronic adjustments for a time, but uneven
wear can produce notches on heads and
guides that will cause the tape to “skew”
and skip around from one path to another,
making adjustment impossible. This ragged
pathway chews up the tape, thus dropping
more abrasive, thus causing more uneven
wear and so — a vicious spiral that can't
be stopped once it gets a good start. The
only solution will then be to replace not
only the heads, but all the tape guides as
well. Being conscientious about cleaning
the tape path on the 32 will more than
double the service life of the head assembly.
1.0
Bin
0.5
ыы Pe,
> A= [OMILS
E
J
a
3 02 \
—
z \
(о Ol
n
Lui
> 0.05
a N A= IMIL
|
ul
e X
0.02 N
OO!
O
0.2 04 0.6 0.8 1.0
SPACING — MILS
Fig. 2-7 Curves showing fall-off of reproduced signals
versus spacing from reproducer head.
(Courtesy, Minnesota Mining and Manufacturing Co.)
0.5 NS
A=IOMILS
N PEAK BIAS
FA |
ss 2dB OVER BIAS
г |
0.2 N
OI
AN
RELATIVE SIGNAL QUTPUT
0.05
A=1 MIL 208 OVER
A= MIL PEAK BIAS
PEAK BIAS N
0.02 \ \
0.01 D
O 0.2 04 0.6 08 1.0
SPACING - MILS
Fig. 2-8 Curves showing the fall-off of recorded signals
versus spacing from recording head.
(Courtesy, Minnesota Mining and Manufacturing Co.)
32
DEGAUSSING (DEMAGNETIZING)
IMPORTANT:
1. Do not overlook the importance of degaussing.
Magnetism in the tape can significantly
degrade performance. In extreme causes, the
heads may not respond to signals at all.
2. Turn off the deck before degaussing.
3. Do not turn the degausser (E-3) off or on
while it is in close proximity to the tape path.
4. Keep all recorded tape a safe distance from
the degausser.
A little stray magnetism goes a long way. A long
way towards making trouble for your tapes. It
only takes a small amount (0.2 gauss) to cause
trouble on the record head and playing 10 rolls
of tape will put about that much charge on the
heads and other ferrous parts of the tape path.
A little more than that {0.7 gauss) will start to
erase high frequency signal on previously re-
corded tapes. Demagnetize the whole tape path,
including the tips of the tension arms every six
fully played 10-1/2" reels. This is a fair “rule
of thumb” even though it may be a bit hard to
keep track of. Fast motion isn't as significant
to the heads, so we don't give an hourly refer-
ence. It's the record/play time that counts.
Degaussing is always done with the recorder
turned off. If you try it with the electronics on,
the 60 cycle current pulses produced by the
degausser will look just like 60 Hz audio to the
heads, at about 10,000 VU and will seriously
damage the electronics and/or the meters. Turn
off the machine, turn on the degausser at least
3 feet away from the recorder. Move slowly in
to the tape path. Move the degausser slowly up
and down in close proximity to all ferrous parts
and, slowly move away to at least 3 feet before
turning off.
It's a good idea to concentrate when you are
degaussing. Don't try to hold a conversation or
think of anything else but the job you are doing.
If the degausser is turned off or on by accident
while it is near the heads, you may put a perma-
nent charge on them that no amount of careful
degaussing will remove — head replacement time
again, we're sorry to say. Make sure you are
wide awake for this procedure.
A clean and properly demagnetized tape re-
corder will maintain its performance without
any other attention for quite some time. Even if
it does drift as a recorder, it won't ruin previ-
ously recorded material, and getting it back in
good shape will not be too difficult.
33
TEST EQUIPMENT/MATERIALS
To make electronic adjustments, you need test
gear, so let's go over what's necessary.
1) Alignment Tapes
You need one for each speed that the recorder
operates at. For the 32 the specs are:
Reference fluxivity: 250 nWb/m
Equalization standard: NAB
15 ips 3180 us + 50 us
(38 cm/sec)
7-1/2 ips 3180 us + 50 us
(19 cm/sec)
Equalization standard: IEC — 1
15 ips co +35 usec
(38 cm/sec)
7-1/2 ips ео +70 usec
(19 cm/sec)
These test tapes are made by several companies,
but there are many different tape specs. Be sure
you have the right one. See page 39.
Reference Fluxivity — How much magnetic
energy is necessary on the tape to ‘make the
meter read “0 VU” in playback? This is the
“benchmark”, or standard you tune your play-
back electronics to. 250 nano Webers per meter
is the correct value for the 32. If a lower or
higher “Reference Fluxivity” is used to set up
the playback, all your other measurements will
be off.
NAB Equalization — Here we have a lot to talk
about. The process of magnetic recording is far
from “flat.” Every circuit in a tape recorder
will alter the level of signal with respect to its
frequency — some deliberately, some unavoid-
ably. The deliberate errors are used to overcome
the unavoidable problems. Here is a selection of
frequency response graphs at various points in
the recording process:
1. The input signal starts this way in the be-
ginning (FLAT).
20Hz 20kHz
Fig. 2-9
2. EQ to overcome head loss at high frequency
and bass anomalies (NAB)
Deliberate error
7-1/2ips ~~
Fig. 2-12
5. Reproduce EQ
Now we must overcome the characteristic
response of heads.
Big deliberate error
Helps lower tape hiss as well as restoring
proper levels to high frequencies.
Fig. 2-10
3. Record Head Response
(6 dB per octave rise until gap in head ap-
proaches wavelength)
Unavoidable error
Small wavelengths (high frequencies) are
partially erased as fast as they are recorded.
7-1/2ips
ISips
Fig. 2-13
6. The result of all this equalization is this
(hopefully).
15 ips
7-1/2ips ~~
Fig. 2-11
We will assume something is recorded, but it's not
flat on the tape either. Now we'll play it back.
4. Reproduce Head Response
(6 dB per octave rise again, same as record
head).
Unavoidable error,
Small wavelengths are not picked up by gap.
Fig. 2-14
The idea is to use the electronics that are ad-
justable to cope with the problems that are
caused by the nature of the magnetic recording
process. We can’t change the basic laws of mag-
netic physics, so we change the record and repro-
duce equalization. Now comes the sticky part.
How much EQ do we use in each stage? If every
manufacturer of tape recorders used their own
standard, their idea of what was best, there
would be no compatibility. Tapes made on
one recorder would not reproduce properly
on another of different make. The standards for
34
record and reproduce equalization are established
by societies of scientists, engineers and users in
the profession. They are:
NAB National Association of Broadcasters
IEC International Electrotechnical Com-
mission
CCIR International Radio Consultive Com-
mission |
DIN Deutsche Industrie Normen
Unfortunately, they don't all agree. Each organi-
zation has a slightly different approach to solv-
ing the problems of tape recording. Scientists
and engineers are human, as well, and have been
known to disagree, sometimes violently about
what ways are best. Advances in the manufac-
ture of tape, improvements in head design, and
the lowering of electronic circuit costs have
made - bizarre solutions quickly change into
practical realities. The optimums have shifted
and will probably continue to do so. Standards
are set by man, not cast in stone.
But while the scientists are boxing in the confer-
ence room, we would like to be recording, so
depending on the equalization requirements of
its final destination, TASCAM has selected the
NAB and |EC standards for record/reproduce
equalization as the recommendation for the 32.
See page 39 for details.
DECIBELS
+
=
0
— 5
20 40 100 200 400 Ik 2k ak Юк 20k
FREQUENCY IN HERTZ
Fig. 2-15 Typical recording (pre-equalization) for 1/4-inch
tape recorders using NAB characteristics.
DECIBELS
20 40 100 200 400 Ik 2k dk 10k 20k
FREQUENCY IN HERTZ
Fig. 2-16 Typical post-equalization for 1/4-inch tape
recorders using NAB characteristics.
+
о
+
un
o
DECIBELS
\
| Г 75: 1
— . IPS
LL P
40 100 200
I
on
o
o
400 1k 2k dk IOk 20k
FREQUENCY IN HERTZ
Fig. 2-17 Typical pre-equalization characteristics for
1/4-inch tape recorders running at 7.5 and
15 ips using the CCIR (DIN) standard.
35
DECIBELS
20 40 100 200 400 Ik 2k 4k IOk 20k
FREQUENCY IN HERTZ
Fig. 2-18 Typical post-equalization curves for 1/4-inch
recorders using CCIR characteristics, at
7.5 and 15 ips.
You will need a separate reference tape for each
speed. The curves are not the same.
Since these Reference Standard tapes cost about
3 times the price of a big roll of the best blank
tape, plan on storing them carefuliy in a place
that will not encounter any magnetic fields that
might damage them — away from loudspeakers,
guitar pickup, tape recorder and record player
motors, power amplifiers (magnetic field surges
in big transformers when amps are turned on
and off can be very powerful) or anything mag-
netic that might alter the quality of the refer-
ence standard. If you don't damage them physi-
cally or magnetically (don't play them on dirty
or magnetized recorders, or loan them out to
the careless) they will last for several years.
If it is not possible to obtain a tape that has
both the NAB EQ anda fluxivity of 250 nWb/m,
select the NAB EQ as the preferred single
standard. A different reference fluxivity requires
only that you make a level correction once. Just
use a different mark on the meter instead of
“zero.” A different EQ curve requires a different
amount of correction for each frequency and is
much harder to use — especially for a beginner.
Level corrections for different reference flux-
ivity:
Use this
instead of
“0” VU
15 ips 185 nWb/m — (Ampex operating
leve!) —3 VU
200 nWb/m — (STL, MRL) —2 VU
7-1/2 ips 185 nWb/m operating —3 VU
sweep fre-
quencies -13 VU
200 nWb/m operating -2 VU
sweep fre-
quencies -12 VU
Below are tabulated some commonly encoutered
flux levels along with their dB differences, and
their differences in dB from 185 nWb/m.
Ampex operating level
3 dB above
Ampex operating level
DIN Standard
6 dB above
Ampex operating level
Note:
Add 0.7 dB for European Measurement Method
Difference
Flux Level
Flux Level Difference from
nWb/m tere 185 nWb/m
in dB
in dB
150 1.82
0.56
160 1.26
0.53
170 0.73
0.50
180 0.24
0.24
185 0.00
0.23
190 0.23
0.45
200 0.68
0.42
210 1.10
0.40
220 1.51
0.39
230 1.89
0.37
240 2.26
0.35
250 - 2.62
0.34
260 2.96
0.04
261.32 3.00
0.28
270 3.28
0.32
280 3.60
0.30
290 3.90
0.29
300 4.20
0.28
310 4.48
0.28
320 4.76
0.27
330 5.03
0.26
340 5.29
0.25
350 5.54
0.24
360 5.78
0.22
369.12 6.00
0.02
370 6.02
0.23
380 6.25
0.23
390 6.48
0.22
400 6.70
using Magnetometer.
IEC Correction Chart (illus.)
+8
+7 15 ips (38 em/sec] Reproducer Characteristics
A — IEC (35 y sec) tape reproduced on a reproducer aligne
ligned to
, to an NAB (3180/50 ¡y sec) tape
В - NA
а
Ik
FREQUENCY IN HERTZ
8 [3180/50 y sec) tape reproduced on a reproducer
an IEC (367 sec) tape
If you must use IEC EQ tapes, these readings
are correct. IEC has less boost in playback,
the tape will read progressively higher as fre-
quencies rise when played on a NAB adjusted
recorder. At 250 nWb/m reference read these
numbers to set |[EC-1 EQ.
31.5 50 125 4001K 3K 6.3K 8K 10K 16K 18K 20K
-5.4 -3.0 -0.6 0 +0.2 +1.2 +2.3 +2.6 +2.7 +2.9 +3.0 +3.0 dB
See “Test Tapes for the 32” on page 39.
Since the low frequency EQ on the 32 is fixed,
the differences are academic. On to the next
piece of test equipment. |
2) VTVM or FET Multimeter
OSCILLOSCOPE
O
oO
o AMP SPKR
o
00
60€
3
VER HOR
Е УТ УМ
DECK
i <
under TEST | oo
(AR) ; O O
SYNC REPRO/REPRO
Fig. 2-20 Head Alignment Fine Adjustment Set-up and
Test Connections (REPRODUCE)
Use a VTVM or FET multimeter with an input
impedance of at least 1 megohm that can read
levels down to —70 (full scale) you can think of
this as a very accurate VU meter of very wide
range. Meters with lower input impedances will
draw power from the circuits to be measured
and will affect the readings. Meters that have
adequate input impedance but do not read
below -40 (0.01 V) can be used for reference
levels and frequency response measurements,
but will not be capable of making signal-to-noise,
erase efficiency or bias circuit measurements
where the output of the circuit being adjusted
is expected to be very low. Meter MUST have
wide, flat frequency response (minimum = 10
Hz — 1 MHz).
This tool is not cheap and is just as important as
the test tapes. Without a good reference meter,
you can do very little in. the way of accurate
adjustment. Spend as much as you can here.
It's worth it. Next. . ..
3) Signal Generator or Oscillator
Here you get a break. A simple oscillator will do
all the work and won't send you to the poor
house. There are several on the market for
36
around $100. The local electronic surplus store
can be a good source for test equipment that can
be re-calibrated by the manufacturer for a reason-
able cost. If you get one with a meter on it, you
won't have to calibrate its output with the big
meter as often. This device is very useful in a
studio for troubleshooting — a good investment.
It should have at least the following frequencies.
40 Hz — 100 Hz — 400 Hz — 1 kHz — 4 kHz
— 10 kH2 — 15 kHz — 18 kHz |
Sine wave is all that is required, at a distortion
of no more than 5%. Most modern units do
better than this easily. This unit is the work-
horse on the equipment list. Whether you are
reading the big meter (FET) or the meters on
the recorder, you will need a signal to read, this
instrument or the test tapes will provide you
with signals.
Test -tapes, tone generator, VTVM or FET
meter. . . . This is the basic package and will do
almost every adjustment in the sequence — ex-
cept the first one. ..
4) The Oscilloscope
Even a simple one is not cheap. Fortunately, a
simple one is all you need. You can spend
$6,000 and more for the big ones, but for this
purpose $100 — $200 will be more than enough.
It must have a “vertical” and a “horizontal”
amplifier and an X—Y mode. That's all you use
to do the one adjustment you need it for.
Assuming that the motors are not in need of
attention (that's for Dealer Service), Azimuth,
or head alignment is the number one step in
maintenance ....so let's begin.
1] TILT 3] HEIGHT
iview from side of head!
tview from front of head:
El TANGENCY a AZIMUTH
(view from top of head: ‘view from front of head!
©: ©
®
T-619
Fig. 2-21 Head Mis-Alignment Example
37
The gaps in the heads that do the erasing, re-
cording, and reproducing must be precisely
perpendicular to the tape. PRECISELY. Even
a tiny error in alignment will make problems
for the recorder. If the heads are not in align-
ment, both with the tape, and with respect
to each other, tones recorded on one head will
not play properly on the other. In the table
below, the error is shown with the loss in dB.
The amount of tilt is given in the fractions of a
single degree called minutes, 60 minutes to a
degree. As you can see, it only takes 1/4 degree
to cause big trouble.
1-Mil Wavelength Y2-Mil Wavelength Ya-Mil Wavelength
Loss Azimuth Loss Azimuth Loss Azimuth
in dB Error in in dB Error in in dB Error in
Minutes Minutes Minutes
0.5dB 14.86 0.5 dB 7.43 0.5 dB 3.71
1.0dB 20.90 1.0dB 10.45 1.0 dB 5.22
2.0dB 29.21 2.0dB 14.60 2.0 dB 7.30
3.0 dB 3.0dB 17.67 3.0dB 8.83
4.0 dB 4.0'dB 20.16 4.0d8 10.08
5.0 dB 50dB 22.16 5.0dB 11.13
6.0 dB 6.0dB 24.08 6.0dB 12.04
7.0 dB 7.0dB 25.68 7.0dB 12.84
8.0 dB 80dB 27.09 8.0dB 13.54
9.0 dB 9.0dB 28.36 3.0dB 14.18
10.0 dB 10.0 dB 29.50 10.0dB 14.75
Fig. 2-22 Loss due to azimuth misalignment for 43-mil
quartertrack. (Courtesy, Ampex Corp. Test
Tape Laboratory)
Since the 32 can use a single head (head #2 in
the stack) to perform all functions (recording,
sync reproduce and reproduce) it won't hurt the
recorder to use the “whizband studio alignment”
procedure, which is to do nothing about align-
ment at all. You won't notice anything wrong
with the sound you make, but there are draw-
backs.
1. Your tapes won't play properly on any other
recorder (whizbang standards are unique).
2. No accurate tune-up of the recorder will be
possible, as most test procedures use one head
as a reference for the other. To do this, they
must be aligned perfectly.
Thread the 7-1/2 ips test tape on the recorder
and find the operating level section of the tape.
Connect the outputs for tracks 1 and 2 of the
recorder to the 2 inputs of an oscilloscope,
track 1 to the vertical input that makes the
beam draw lines up and down and 2 to the
horizontal input (draws lines left to right). Set
the scope to the “Vector” or XY mode. You
will have to consult the instruction book
for the scope to determine how to do this. We
don't know what brand of test gear you have.
Play the tone, and this is what you should see:
Trace for Track Trace for Unequal
1 alone Track 2 levels.
alone One track
or the other
is dominant.
If the lines are not the same length for
each track alone, it indicates that the 2
tracks are not putting out the same level.
Adjust with the scope controls.
If the playback head is not straight up and
down, you will see this kind of picture:
4 5 6
(A larger error (A big one,
90° outof phase) 180° out of phase)
{A small misalignment
30° out of phase)
7
Note: Some scopes show in
phase diagonal pointing to
the left.
(Perfect azimuth
0°, in phase)
Fig. 2-23 Phase Shift
How much distance error is involved depends on
the frequency or pitch of the tone and the speed
of the tape. One “cycle” per second at 15 ips
would be hard to misalign. To get scope picture
No. 6, you would have to separate the gaps in
the playback head by 7-1/2 inches, but one
cycle per second is not audio. How about 1,000
cycles per second of tape travel? At 15 ips, the
separation or tilt in the head for scope picture
No. 6 becomes 0.0075 inch. And at 15,000 Hz
at 15 ips it's 0.0005 inch. Not much tilt will pro-
duce a big error. Slower tape speeds mean even
smaller spacings and good azimuth becomes
even more important. The proper method of
adjustment is to look first at a long wave, say
1000 cycles, and make a coarse adjustment.
Then work up in frequency, adjusting shorter
and shorter wavelengths smaller and smaller
amounts. If you start adjusting with 10 kHz or
15 kHz, you can make a big mistake. Here's
why. . . . Since the very short wavelengths are
very close together on the tape, it is possible to
get a good “picture” on the scope by adjusting
one full cycle off. If you work up to 15K,
WAVE LENGTH IN INCHES
checking and adjusting as you go, you will avoid
this mistake.
0.0001
0.001
0.0!
10 го 50
ЮО 200 500 Ik 2k Sk I0k 20k
FREQUENCY IN HERTZ
Fig. 2-24 Velocity of recording media versus recorded
wavelength in inches for a given frequency.
Once you have everything set up — the reference
tape is playing, the scope is running and showing
the x-y display, you need a screwdriver and this
diagram to find the right adjustment point.
Adjusting the screw will rotate the head very
slightly.
00%
Dos
O
(1) Erase (2)Record/Sync (3)Repro
Head Head Head
® AZIMUTH ADJ. SCREWS
O HEIGHT AND TILT ADJ. SCREWS
@ TANGENCY ADJ. NUTS
Fig. 2-25 Head Adjustment Screws and Alignment
38
5) Test Tapes for 32 (reproduce alignment)
NAB Equalization:
STL 3 or MRL 21J205 = Tape speed 15 ips
STL 22 or MRL 217204 = Tape speed 7.5 ips
Reference fluxivity; 250 nWb/m
Time constant; 3,180 + 50 usec.
|EC-1 Equalization:
STL 3-1EC or MRL 21J103 = Tape speed 15 ips
Reference fluxivity; 200 mWb/m
Time constant; ee + 3b usec.
STL22-IECor MRL21T102=Tape speed7.5 ips
Reference fluxivity; 200 nWb/m
Time constant; o + 70 usec.
NAB Equalization:
TEAC YTT-1044 = Tape speed 15 ips
Reference fluxivity; 185 nWb/m
Time constant; e + 35 usec
|EC-1 Equalization:
TEAC YTT-10432 = Tape speed 7.5 ips
Reference fluxivity; 185 nWb/m
Time constant; «= + 70 usec.
All specs are identical with STL or MRL tapes
except for the reference fluxivity which is 185
nWb/m, and thus, its reproduce output level will
be 3 dB lower compared with 250 nWb/m
fluxivity. Calibration level under “Reproduce
Calibration’ refers 0 VU as 250 nWb/m.
CAUTION: As mentioned before TASCAM has
selected the NAB and IEC standards for record/
reproduce EQ as the recommendation for the 32.
The NAB standard is chosen for the models
which are to be sold in the U.S.A. and Canada,
or for General Export models, while the IEC
standard chosen for the models designated for
Europe, U.K. and Australia.
Note: If necessary, inter-switching between the
NAB and IEC standards can be accomp-
lished by simply removing and repatching
the jumper wires on five points of the
amplifier. The details are explained as a
note in the inserted schematic of the
amplifier section.
39
The next step is to play all the signals from the
lowest frequency to the highest on the 7-1/2 ips
alignment tape — one play for each head posi-
tion (2—3), and DO NOTHING. Just have a look.
[t's not a good idea to turn knobs just to “see
what happens.” Just because an adjustment can
be made doesn't mean it's necessary. The re-
corder is very solid and is well adjusted at the
factory, so in all test and maintenance proce-
dures, check first, then if something is not right,
adjust. Taking your time will save endless grief.
A new machine is very likely to be “on the
money” when you get it and if you keep it clean
and degaussed will drift away from top shape
very slowly. It's not necessary to plan on a
major overhaul when it comes out of the box.
ELECTRICAL ADJUSTMENT PROCEDURE
1) Location of Electrical Adjustments:
MONITOR AMPL,
PCB Ass'y
/ MO ON #7 NN
тез a De тал | L104 L103 \ R140 | | | 2109 08
TP.2 #8 L105 RECEQ R176 # MT R141 R122 R120 Cow HI 75 |
C134 BIAS REC R156 CAL REPRO SYNC REPRO L____i REPROEO
BIAS TRAP CAL INPUT MT CAL CAL NC EQ '
CAL CAL
TRIM POT REFERENCE NUMBER
FUNCTION
NUMBER Tape Speed 15 ips Tape Speed 7-1/2 ips
#1 R120 2k ohms — REPRO CAL
2 R122 2k ohms — SYNC CAL
3 R141 50k — REPRO METER CAL
4 R108 10k R109 10 kohms REPRO EO
5 R110 20kohms R111 20 kohms SYNC EQ
6 R156 2k — INPUT LEVEL
7 R140 50k — INPUT METER CAL
8 C134 100p Max. — BIAS LEVEL
9 R176 20k — REC LEVEL
10 L103 1.4 mH L104 2.4 mH REC EQ
— L105 — RECORD BIAS TRAP
CAUTION; Don’t attempt any adjustments of
— L106 (BIAS TUNING) L106 except for purposes described
under the MAINTENANCE section.
2) Reproduce Calibration:
(DO NOT ATTEMPT TO CALIBRATE WITH
DBX ENGAGED!)
When we're sure the reproduce and record head
are properly aligned, we can move on to the
electronic adjustments.
The first step here is to actually check your
meter calibration. To open the bottom panel,
remove the 8 binding screws. Rotate QUTPUT
knob on the front panel to the position “7”.
Connect the VTVM to the output terminal of
left channel. Turn the machine ON, and thread
the 15 ips alignment tape. Play the “operating
level” portion (a voice on the tape identifies
each section at the beginning).
Switch the OUTPUT SELECT on the 32 to
REPRO. Adjust the playback or “reproduce”
level with trim pot #1 R120, 2k ohms (REPRO
CAL), until the VTVM reads -10 dB (0.3 V).
Switch the OUTPUT SELECT to SYNC. Adjust
the reproduce level with trim pot #2 R122,
2k ohms (SYNC CAL), until the meter reads
-10 dB (0.3 V). Now read the meter on the
front panel of the 32. It should read “0 VU”.
If it does not, adjusting trim pot #3 R141
50k ohms (METER CAL) will allow you to set
the meter on the 32. You adjust the 32 meter to
read “0 VU”, not -10, the reading on the VTVM.
The meter will read O at any voltage you set it
for, the correct one is 0.316 Volt. This is the right
setting for the 32. You read -10 dB (0.3 V) on
the VTVM and adjust the 32 meters to read
O VU at this level.
Channel R still remains to be checked and
adjusted, but as you can see, the adjustments are
the same as for channel L. In brief:
. Play the tape “operating level”
. Read the VTVM for head 3, REPRO.
. Adjust for -10 dB (0.3 V) reading with trim
pot +1.
. Switch to SYNC on OUTPUT SELECT.
. Read the VTVM. Adjust trim pot # 2.
. Read the meter on the 32 — it mustread 0 VU.
. Adjust the meter trim pot #3 R141,50k ohms
METER CAL.
ON
“Von.
One more word of encouragement. The circuits
in the 32 are very stable. Most of the time you
will make a reading and not have to adjust
anything. When something does go wrong, you
will be able to fix it very quickly, and get back
to recording.
In summary, with the VTVM and test tape, you
have adjusted the reproduce level on the 32 to
the test tape. But your reproduce reference is
not yet complete. You have only ‘zeroed’ one
point on a line of frequency response. To establish
the rest of the line, you must measure and adjust
one more frequency.
Advance the alignment tape for 15 ips to the
section that is recorded at 16 kHz and adjust the
trim pot marked REPRO EQ #4, R108, 10k
ohms — switch to SYNC on the OUTPUT
SELECT, and adjust trim pot #b, R110, 20k
ohms SYNC EQ.
The reading for both positions should be 0 VU
on the 32 meters. Since you have checked and
adjusted the reproduce meter circuit, you now
can use the meterson the 32 for the test readings.
#6 В
‚8156
41
R140
3 2 m | * | 4
R141 R122 R120 R111 R110 R109 R108
By adjusting all of the preceding trimmers, you
have established two things: an operating play-
back level or “zero”, and a playback frequency
response reference. You know that both heads
on the 32 are reproducing the test tape in an
identical manner, at 15 ips.
You now repeat the frequency adjustments for
both heads at 7-1/2 ips. Change test tapes and use
trim pot #4 R109, 10k ohms and adjust the
high frequency playback response for “REPRO”.
The reading on the meter should be “0 VU”.
If you are still using the VTVM, the reading will
be -10 dB. The test frequency is 18 kHz.
Repeat the adjustment for “SYNC” trim pot
#5 R111, 20k ohms at 18 kHz. The reproduce
response section is now complete for both
speeds.
3) Input Calibration:
It stands to reason that you should monitor the
level of the signals which are going to be record-
ed, before actually making the recording itself.
This monitoring signal can be fed to the VU
meters and, at the same time to the output
terminals. The required procedures are:
Connect the reference level, or signal generator
to channel L input on the 32.
The correct level is -10 dB (0.3 V).
The frequency to use is 400 Hz. Rotate INPUT
knob and OUTPUT knob on the front panel to
the “7” position. t's a good idea to mark it. Check
the OUTPUT SELECT. Make sure you have the
button marked INPUT depressed. If you get a
reading, use trim pot #6, R156, 2k ohms,
INPUT LEVEL, and adjust the meter to read
O VU. If you have a VTVM, connect it to the
output terminals, and adjust the input level by
using trim pot #6, R156, 2k ohms to obtain the
correct -10 dB (0.3 V) level. Plugging and un-
plugging test equipment can be tedious. You can
save some time by doing a reference check on
your mixer. If you know that your console
meter reads O VU accurately (check it with the
VTVM), you can assign the reference oscillator
signals to the 32 through the mixer connections
to the inputs. Assign, read, adjust: next track,
assign, read, adjust ... no need to pull plugs.
Record Calibration
OSCILLOSCOPE
OSCILLATOR 9
12:
...
QO VERT
AMPL SP
VTVM
DECK (E) OUTPUT
under TEST KE °° A
ATTENUATOR
Test Connection for Recording Check
Now you can use the REPRO head as a test
instrument to check and adjust the record
circuits. Almost all of the following steps involve
recording a tone on a tape and reading the repro-
duce output of the recorder. YOU WON'T
ALTER THE REPRODUCE CONTROLS. They
are all set. You will make all necessary adjust-
ments by trimming the record electronics.
This way, you can be sure that the recordings
you make, no matter what brand of tape you
use (the brand of tape becomes part of the test
tones on it), will reproduce properly on any 32.
The alignment tape can be put away. Before
storing, the tape should be played all the way
from front to back (not fast wound), and stored
tails out, so it will last longer. Even if you decide
not to attempt any major maintenance yourself,
we strongly suggest that you purchase an align-
ment tape. An occasional playing will tell you
when you need to call the “doctor”. It's good
insurance to know the truth.
The record adjustments begin with the INPUT
LEVEL trim of the 32. The INPUT LEVEL
controls the meter reading of the signal as it
arrives at the electronics (before it is recorded).
You must be sure you are sending the right
amount of signal in before you can adjust record
levels and equalization controls.
42
4) About the Bias
At this point in the adjustment procedure we'll
stop for a time and talk about a major section of
the recorder electronics: the oscillator and its
related circuitry. The oscillator produces a very
high frequency signal that does two big jobs in
the 32. It supplies the 150 kHz (one hundred
fifty thousand cycles per second) frequency to
the bias amplifier in the 32. There is a bias
amplifier on every card, one for both tracks. The
bias amplifier provides power for the erase head
and bias signal for the record head. Erasure is
easy to explain, so we'll tackle that subject first.
A lot of power is used to remove all signal from
the tape just prior to its being recorded. The
erase head has a rather large gap and completely
cleans off any magnetic field on the tape by
brute force. No new signal is recorded by this
head. The gap is much too large to be effective
as a recording device.
From the same amplifier, current is added to the
record head circuit lead. This high frequency
signal overcomes magnetic inertia in tape, and
gets everything moving. If there were no “starter
current” to help the record signal, we would see
this kind of trouble on a scope.
WITHOUT BIAS Distorted
lf we put this in .. .. We would get this out .. ..
The beginning and ending points of the wave
would be distorted by the reluctance of the iron
bits to change their magnetic state from one
polarity to the other. Crossing that zero line
takes extra energy. The bias signal provides it.
We put in this:
A A
\/ NU
If we put thisin.... Audio and Bias mixed .... .... and get Back this ..
Where did the 150 kHz go? It disappears from
the output because the head gap is too large to
play it back. The individual changes of magnetic
energy on the tape are smaller than the gap size
so a plus and minus wave are both within the gap
at the same time. They cancel out. Marvelous!
On with the problem of alignment.
Well, maybe not so marvelous. Because of the
fact that there is one amplifier dojing 2 separate
jobs. The adjustments we make on one circuit
will affect the other. In fact, the erase current
fixed, but there are 2 interfacing circuits and life
can get pretty tricky right here. The 2 adjustables
are (in sequence):
1. The bias current (for the record head) trim
capacitor C134 100P max. BIAS LEVEL.
2. The bias traps. Since there is a lot of power
involved here, you have 2 problems.
L BIAS
REC AMP AMP
R REC HEAD
H 9 aE
Yes —
с no
43
We've give you the bad news (they interact).
Now we'll give you the good news. Unless you
adjust the erase current or the bias current by a
very large amount, you won't need to check
these circuits more than once every six months
or so. The traps seldom need adjustment unless
something is wrong with the master oscillator.
The “traps” are expected to tune out the
150 kHz frequency that the bias oscillator is
producing, and the range of adjustment that
they have is not very good at filtering a much
different frequency. If the master bias oscillator
drifts, it must be re-adjusted to produce 150 kHz.
Since this bias oscillator master circuit adjust-
ment requires something expensive (very) called
a frequency counter, it's wise to assume ¡t's
a dealer problem, Cart it in for this kind of
service. There are also bias traps in the reproduce
circuit to keep any stray leaks out of them as
well, but they are not as touchy as the record-
related circuit traps, and won't affect the load
on the bias amplifier. They are tricky to adjust,
but very stable. In sequence, you adjust them (if
necessary) at the very end of the entire alignment
procedure so we'll mention them again.
5) Bias Level Adjust:
This adjustment is made whiie you are recording
a tone on the type of tape you'll be using for
the session. it will be different for each brand of
tape. Set up the signal generator {oscillator}. The
frequency is 7 kHz, -10dB (0.3 V}. Depress
INPUT SELECT to LINE, and set both FUNC-
TION buttons to ON, then set INPUT and
OUTPUT knobs to the “7” position. The level
should be O VU on the meters of the 32 on
INPUT. Start the machine at the tape speed
7-1/2 ips, record the signal, and switch to
REPRO on the OUTPUT SELECT.
Begin the adjustment by making sure trim
capacitor #8 C134 100P max. BIAS LEVEL isin
the fully CCW position {off, no bias at all}. Now,
as you rotate the trim pot #8 CW, the VU meter
will rise to some peak reading. CONTINUE THE
CLOCKWISE ROTATION SLOWLY until the
reading on the meter drops back 4 — 6 dB from
the peak.
If, at peak the meter goes off scale, adjust the
INPUT level controls to keep the reading on scale.
What is important here is not the zero. lt is the
reduction of the peak by 4 — 6 dB. If you have
moved the input level pot on the front panel of
the 32 to keep your reading on scale, the next
adjustment will correct your input reference.
Decrease
OUT
7 kHz
—w BIAS
{Pot rotated clockwise}
Bias Limits Chart
If there is insufficient CW rotation of #8 to
achieve a peak, dealer service of the bias am-
plifier/oscillator system will be required. Many
voltages in the circuit must be adjusted accurately
and this type of problem is not considered to be
“Daily Maintenance”. Bring it in.
When doing bias adjustment, both channels
should be recording at once, even though you
are adjusting only one at a time.
With the oscillator running at 400 Hz, switch
back to INPUT. Set INPUT and OUTPUT knobs
on the front panel to the “7” position and
adjust trim pot #6, R156 INPUT LEVEL for
0 VU indication on meters.
44
6) Bias Trap Adjust:
Now is the time to do the bias trap in the record
circuit: with no input signal, adjust test point
TP1 located on the PC Board. Positive side of
the VTVM is connected to the test point,
negative side to ground. Tune inductor L105 for
minimum,
L105
TP1
c131
7) Record Level Adjust:
We give these adjustments just to be accurate
and thorough, and remind you again that they
are seldom needed. Unless you have made some
really drastic change in your recorder, you
should not worry about this adjustment for at
least 6 months.
Again, to be thorough, at this point it would be
wise to check erase and bias again before pro-
ceeding. Once you start a major overhaul it might
be necessary to go through these 3 steps — erase,
bias and record level adjustments — 3 or 4 times
before finally moving on to the “record equaliza-
tion” and then, once more from erase through to
the end. Describing the way is probably giving
the manufacturing setup, or head replacement
sequence when all values of the record circuit
must be re-qualified. If noise is heard, signals
don’t erase completely even after adjustment, or
there is not enough rotation of the bias trim pot
left to get a “drop” in bias, the whole adjustment
should be considered, but only under these
unusal circumstances.
However, we do recommend that you select a
brand of high quality tape and stick to it. Chang-
ing bias every day for different tapes will make
the recorder cranky and a little harder to adjust.
Constant messing with the controls is unwise
It is a much better idea to do as little as possible
and let the recorder “‘settle in” to one kind of tape.
We are now ready to adjust the record circuitry.
We first check the low frequency input level at
400 Hz to get a reference. The steps are as
follows:.
1. Adjust oscillator to 400 Hz.
2. Select “LINE” on INPUT SELECT buttons.
3. Set INPUT and OUTPUT knobs on the front
panel to the “7” position.
4, Select “INPUT” on OUTPUT SELECT
buttons.
5. Set both FUNCTION buttons to ON.
6. Send in 0.316 V, set “0 VU” on the 32 meter.
7. Record the tone at 15 ips.
8. Switch to “REPRO”, read the 32 meter.
9. With trim pot #9 R176, 20k ohms (REC
LEVEL), adjust to “0 VU”.
With only a few adjustments remaining in the
complete procedure, let's review alk you have
done up to this point. Step by step, you have:
1. Cleaned and degaussed the tape path.
TP-1 LI | #10 #9
L105 Joa L103 R176
LOW
45
2. Adjusted the head azimuth of both heads to
90° by checking and adjusting progressively
higher and higher frequencies.
3. Checked the 32 meters against a precision
meter and set 0.316 V output as “0 VU”
reproduce. |
4. Adjusted reproduce from both playhead
positions to be “0 VU” at 400 Hz using the
test tapes as an absolute reference of magnetic
level.
5. Applied a reference level to the input of the
32 and adjusted the “0 VU” point to be
0.316 V, both in the circuit and on the meter.
6. Set bias level for the tape of choice.
7. 1f you have the equipment, make sure no bias
Is going to the record amplifiers.
8. If you have the equipment, set (after bias) the
record “O VU” and read it off reproduce. You
now know that the tape you are making has
the same level of magnetic flux recorded on it
as the reference alignment tape, but only at
400 Hz, the basic adjustment frequency.
8) The Peak Adjust Circuit
The choke coil in this circuit only has a very
small range, 1 dB at tape speed 15 ips. It is for
final high end adjustment. The frequency to
send in is 20 kHz, record the tone at “0 VU”,
switch to REPRO and read the result. Adjust
choke coil +10 L103 to read “0 VU” in repro-
duce.
Both of the record equalization circuits have
rather a smali range of adjustment. The high
frequency adjust is 3 dB, the peak adjust is 1 dB.
If you can’t seem to get a ‘good’ reading because
you run out of adjustment range, check these
3 points.
eThe “record adjust” (point #8 in this review).
Re-do, send in ‘’O VU” at 400 Hz. Record the
tone and read reproduce. If it is low, it will be
impossble to get 18 kHz or 20kHz up to
“0 VU”. Reset and try again. Still no good?
Re-check the bias. If the bias current is too
high, the high frequency sensitivity is reduced
in relation to the 400 Hz point. Check it out.
Tape Speed 15 ips (38 cm/sec)
RESPONSE IN dB
4 ; + +
E » © a a
TK
FREQUENCY IN Hz
7-1/2 ips tape speed adjustments still remain to
be checked and adjusted. The procedures for
adjustment are the same as the 15 ips adjust-
ments, but the test tape has to be changed. Send
in a 16 kHz frequency and record the tone at
“0 VU.” If you get a low reading, adjust the #10
choke coil, L104 to read “-3 VU,” or higher as
necessary.
Tape Speed 7-1/2 ips (19 cm/sec)
RESPONSE IN dB
' : + +
+ vb 8 bo +
40 106 400 TK 1 20K
FREQUENCY IN Hz 16K
If all this fails to produce a reading that lives
within the tolerances for frequency response on
this graph, it is time to replace the heads. If
more equalization were added to the record
circuit to overcome wear, the boost needed
would be large enough to make the signal-to-noise
ratio specification impossible to achieve.
Let's assume everything is OK so far. You have
sent in and read back good numbers for 15 ips,
everything in spec at both frequencies. Now, as a
check, record everything you have on your tone
generator (If it is variable be reasonable, say
9 frequencies) 40 Hz, 100 Hz, 400 Hz, 1 kHz,
4 kHz, 10 kHz, 18 kHz, 20 kHz — compare with
the graph above.
Fine tuning the bias against the frequency trim
pots will allow you to get a little closer to
perfectly flat. It's time consuming but worth-
while, Suit yourself.
With the bottom panel closed, you can now check
the signal to noise of the whole system. You use
the big test meter and a noise filter. Record with
no input signal and read the result. The reading
should be -50 dB or better (un-weighted).
46
That's it. The whole procedure for an electronic
overhaul of the 32. Mechanical adjustments such
as brake and holdback torque, reel height adjust
and wow and flutter measurements must be
done first, but they are major service and should
not be necessary “out of thebox”. The transport
logic control and switching system are described
in the maintenance section. But digital |.C.
theory is very complex and the necessary test
equipment for repairs costs more than the
recorder. The maintenance section is not written
as a guide to the beginner, so be advised, it may
not help your understanding of the 32. It is
useful only to the experienced maintenance
technician.
47
DAILY SETUP
It’s obvious that this entire procedure is not some-
thing that can be completed quickly. You dont
begin a ‘‘major’’ ten minutes before the musicians
arrive. It is not likely to be necessary every day,
but what is reasonable? Most good engineers
make several quick tests. If nothing is amiss,
they start setting up the rest of the session with
confidence. If there is a problem, they go
further. Here is what they do.
1. Clean and degauss. Obvious first step.
2. After the recorder has been on for 10 minutes
and is nicely warmed up, they check the
reproduce response with the test tape. A
little trim? OK, no problem.
3. They then set up the signal generator and
record several frequencies, say 100 Hz, 4k,
10k. Looks good? Then we can begin.
4. A very fussy engineer will take a look at the
bias adjust to make sure everything is OK
there as well, before he looks at the record
EQ.
These several quick checks will usually uncover
any serious trouble, and the idea is to work
backwards up the chain of adjustments if any-
thing shows an error. “Reproduce” is the first
step in a major overhaul, and Record EQ is the
last. If everything works OK, you can assume all
is well. If you get something funny as a reading,
you will have to track it down, but these
tests will usually give you some idea of where
the problem lies. Work backwards through the
recorder (that's forward through the adjust-
ments, by the way, they run from back to front
in the procedure, don't get confused) until you
uncover the problem. You always clean and
degauss, and you should always check the
reproduce response with the test tape. Again,
reproduce, bias, record check, no problems, OK,
go, and good luck with your tapes.
Speaking of tape, the 32 has been designed to
use 1.5 mil tape, the use of 1 mil tape 1s not re-
commended, we strongly suggest that you buy
good quality tape and stick to one kind. White
box tape is cheap for a reason. It doesn't per-
form as well as the “good stuff”, and will be
hard to tune up to, and may even damage your
recorder. Excessive shedding of oxide, uneven
slitting and other defects too numerous to men-
tion will make all your efforts go for very little.
Tape is important, use the best.
GENERAL ADVICE ON MAINTENANCE
Don’t attempt to adjust a stone cold machine.
Turn it on and let it warm up for 30 minutes.
Don't adjust the “traps” with a metal screw
driver or tool. The metal tip will affect the value
of the part and will give false readings. Use a
plastic T.V. adjustment tool, or cut a strip of
rigid plastic to size. (Credit cards will work, if
you have an old one you don't need.)
Suspect any large change in adjustment that hap-
pens all at once.
Stop and think, if you turn a pot and get no
change in reading, have you adjusted the wrong
control?
Always turn the machine “off” when installing
the extender card.
Remove the alignment tape from the heads
when switching power “on” or “off.” A switch-
ing transient on a badly adjusted recorder can
“print” on the tape.
Tape and electronic “hiss” should be smooth
sounding. If, when recording, you detect pop-
ping, or sputtering noises, degauss the heads. If
this doesn’t change the sound, plan on a record
bias trap adjustment.
If the oscilloscope picture is not stable when
using the alignment tape (the trace opens and
shuts like a mouth) suspect the holdback torque
adjustment. When recording and playing test
tones, suspect the tape slitting as well as the
motor adjusts. If the reference tape doesn’t do
this, but the recording tape does, it's definitely
not the recorder. It is the tape that is at fault.
At the end of a session, take the time to slow
wind (play) the roll off the machine and store it
tails out.” This is the best way.
Don’t plan on recording over asplice. Any steady
tone such as singing, or violins that you attempt
to print over a cut in the tape may show a drop-
out, or momentary interruption. Even the best
splice in the world is thicker than normal. The
splicing tape adds quite a lot, and makes the
tape “bump” when it goes by the head. This is
especially important if you are using DBX. The
dropout will be made much more noticeable by
the action of the DBX.
It is a good idea to pad your master tapes by
winding some blank tape on both ends, and add-
ing leader tape.
Puta test tone (1 kHz) on each tape for reference
level checks. Then it's easier to set up machines
and mixers when recording sessions occur on dif-
ferent dates or different machines.
Keep a TRACK SHEET. Write down what hap-
pened during the session and what went on to
the tape. Y ou might list such things as mic place-
ment; complete/incomplete takes; brand of tape
used; speeds; noise reduction; comments (for ex-
ample: a producer might have liked a particular
bass part more than others, so you can save It
and use it during overdubbing and mix-down).
Have the tools of the trade handy — leader tape,
razor blades, splicing tape, masking tape, grease
pencils, etc.
There's another old saying around studio circles:
If it's not labeled, use it. So it's a very good idea
to label all tape boxes and reels. And pack a track
sheet in every box.
When you're not working on a tape, it’s safest to
put it in its box; don't leave it on the machine
where an accident could wipe out weeks of work.
48
SERVICE CHART
fost WHAT IS IT SIGNAL SOURCE | WHAT TEST WHAT IS THE RE- | POINT TO WHAT READING TO
sTep | CALLED AND AMOUNT GEAR TO USE CORDER DOING? ADJUST ADJUST FOR
1 Reproduce head | TEAC YTT-1003 VTVM and Oscil- | Playback at 7-1/2 Repro head #3 | Adjust for maximum
Alignment Playback Align- loscope with verti-| ips speed. OUTPUT azimuth adjust- | output and for output
ment Test Tape cal and horizontal | SELECT at REPRO. | ing screw. of tracks L and R less
(7-1/2 ips) inputs connected | OUTPUT knob at than 90° out of phase.
to OUTPUT position "7°" (at 12.5 kHz)
channels L and R.
2 Sync head Align- | Same as above Same as above Playback at 7-1/2 Record head Same as above (at 10 kHz)
ment ips speed. OUTPUT #2 azimuth
SELECT at SYNC. adjusting screw
OUTPUT knob at
position “7”.
3 x Reproduce Level | TEAC YTT-1004 VTVM connected | Playback at 15 ips Trim pot 41 -10 dB (0.3 V) an
(head #3) Playback Align- to OUTPUT speed. OUTPUT R120 (REPRO |VTVM
ment Test Tape terminal SELECT at CAL)
(15 ips) REPRO.
Play 400 Hz re- OUTPUT knob at
ference level signal. position “7”.
4x | Sync Reproduce | TEAC YTT-1004 Same as above Playback tape at 15 Trim pot #2 -10 dB (0.3 V)
Level (head #2) | Playback Align- ips. OUTPUT R122 (SYNC |on VTVM
ment Test Tape. SELECT at SYNC. CAL)
Play 400 Hz re- OUTPUT knob at -
ference level signal. position “7”.
5 « REPRO Meter Same as above VU Meter Same as above Trim pot #3 Adjust to read 0 VU on
Adjustment R141 VU meters
(METER CAL)
REPEAT STEP MARKED WITH AN ASTERISK FOR EACH CHANNEL. THE ADJUSTMENT NUMBERS ARE THE SAME BUT
THE CIRCUIT BOARD LOCATION, INPUT/QUTPUT TERMINAL NUMBERS, VU METERS, ETC., WILL BE DIFFERENT
DEPENDING ON THE CHANNEL.
6 + REPRO EQ at 15| Test Tape VTVM connected | Playback at 15 ips Trim pot #4 Adjust to read 0 VU on
ips speed (head | Play 16 kHz signal | to OUTPUT speed. OUTPUT R108 (REPRO | VU meters or -10 dB on
+3) on the tape. terminal or VU SELECT at REPRO. | EQ) VTVM
meter OUTPUT knob at
position “7”.
7% Sync Reproduce | Same as above Same as above Playback at 15 ips Trim pot #5 Same as above
EQ at 15 ips speed. OUTPUT R110 (SYNC
speed (head #2) SELECT at SYNC. EQ)
OUTPUT knob at
position “7”.
8 x REPRO EQ at Test Tape Same as above Playback at 7-1/2 Trim pot #4 Same as above
7-1/2 ips speed. | Play 10 kHz signal ips. OUTPUT R109 (REPRO
(head #3) on the tape. SELECT at REPRO. | EQ)
9x | Sync Reproduce | Same as above Same as above Playback at 7-1/2 Trim pot #5 Same as above
EQat 7-1/2 ips ips. OUTPUT R111 (SYNC
speed (head #2) SELECT at SYNC. EQ)
OUTPUT knob at
position “7”.
10 » | input Level 400 Hz signal at Same as above Stop mode Trim pot #6 Same as above
-10 dB from oscil- INPUT SELECT at R156 (INPUT
lator connected LINE. LEVEL)
to LINE IN OUTPUT SELECT
terminals. at INPUT.
INPUT and OUT-
PUT knobs at
position “7”.
11 x INPUT Same as above VU meters Same as above Trim pot #7 Adjust for 0 VU
Meter Adjust- R140 (INPUT ton VU meter
ment METER CAL)
49
AD-
JUST | WHAT IS IT SIGNAL SOURCE | WHAT TEST WAHT IS THE RE- ¡POINT TO WHAT READING TO
$ТЕР | CALLED AND AMOUNT GEAR TO USE CORDER DOING? ADJUST ADJUST FOR
12x Bias Level Ad- 7 kHz, -10 dB VTVM connected | Record signal on type | Trim capacitor | While recording adjust
justment oscillator signal to OUTPUT jacks. | of tape that will be #8 trim pot until VU meter
Refer to connected to line used for actual record- | C134 (BIAS indication rises to peak
MAINTENANCE | input jacks. ing. FUNCTION atON.| LEVEL) value, then turn pot
section for more
precise adjust-
ments.
INPUT SELECT
at LINE.
OUTPUT SELECT
at REPRO.
INPUT and OUTPUT
knobs at position 7”.
Tape speed at 15 ips.
further clockwise until
signal drops off by 4 —
6 VU (over-bias).
IF INPUT AND QUTPUT KNOB ARE MOVED, REPEAT STEP 10 CONDITIONS TO RESET.
13 + Bias Trap Ad- No input signal VTVM connected | Record mode, no Trim capacitor | Adjust capacitor for
justment to Bias Trap test | input signal L105 minimum output at
point TP1, nega- Bias Trap test point TP1.
tive lead to See page 45 for test
ground, positive point location.
lead to test point.
14 » | Record Level 400 Hz signal at VTVM connected | Record signal on type | Trim pot #9 Set for -10 dB (0.3 V)
-10 de (0 VU on to OUTPUT jack | that will be used for [R176 (REC at QUTPUT jacks or O
VU meters) con- or use VU meters. | actual recording. LEVEL) VU on VU meters.
nected to input INPUT SELECT at
terminals. LINE. FUNCTION at
ON.
OUTPUT SELECT
at REPRO.
INPUT and OUTPUT
knobs at position 7”.
Tape speed at 15 ips.
15 + Record Re- 40 Hz to 22 kHz Same as above Same as above Inductor #10 | Check that frequency
produce Fre- signal at -10 dB L103 response matches limits
quency Res- connected to given in Chart.
ponse at input terminals. See page 46.
15 ips speed.
16 + Record Re- 40 Hz to 16 kHz Same as above Record signal on Inductor #10 | Same as above
produce Fre- signal at -10 dB type of tape that L104
quency Res- connected to will be used for
ponse at input terminals. actual recording.
7-1/2 ips speed INPUT SELECT at
LINE.
OUTPUT SELECT at
REPRO.
INPUT and OUTPUT
knobs at position “7”.
Tape speed at 7-1/2ips.
17x | Overall Signal- No input signal VTVM connected | Same as above Check for -50 dB or
to-Noise Ratio
to OUTPUT jacks.
tape speed at
15 ips or 7-1/2 ips.
better.
50
TASCAM
TEAC Professional Division
TEAC CORPORATION
3-7-3, Nakacho, Musashino-shi, Tokyo 180, Japan Phone: (0422) 52-5081
TEAC AMERICA, INC.
7733 Telegraph Road, Montebello, California 90640 Phone: (213) 726-0303
TEAC CANADA LTD.
340 Brunel Road, Mississauga, Ontario L4Z 2C2, Canada Phone: 905-890-8008
TEAC UK LIMITED
5 Marlin House, Marlins Meadow, The Croxley Centre, Watford, Herts. WD1 8YA, U.K. Phone: 0923-819631
TEAC DEUTSCHLAND GmbH
Bahnstrasse 12, 65205 Wiesbaden-Erbenheim, Germany Phone: 0611-71580
TEAC FRANCE S.A.
17, Rue Alexis-de-Tocqueville, CE 005 92182 Antony Cedex, France Phone: (1) 42.37.01.02
TEAC NEDERLAND BV
Perkinsbaan 11, 3439 ND Nieuwegein, Nederland Phone: 03-402-30229
TEAC AUSTRALIA PTY., LTD.
A.C.N. 005 408 462
106 Bay Street, Port Melborne, Victoria 3207, Australia Phone: (03) 646-1733
TEAC ITALIANA S.p.A.
Via C. Cantu 5, 20092 Cinisello Balsamo, Milano, Italy Phone: 02-66010500
NN
PRINTED IN JAPAN 1297U0.5 D-3964AC J
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