CH2-M Vacuum tube 2-Channel Microphone pre, with master

CH2-M Vacuum tube
2-Channel Microphone pre, with
master control room console
OWNER’S MANUAL
Signal Audio Workshop
53 Abarbanel ST.
Tel Aviv 66089 Israel
P.O.B 5169 TLV 61051
Office: 972-3-6820892
Fax: 972-3-6824716
www.signal-audio.com
CH2-M Owner’s Manual
Content:
Preface__________________________ 3
Front panel controls _________________
4
Rear panel _______________________ 5
Construction options________________5-6
Signal chain______________________ 6-7
Psu15 power supply_________________8
Tips & Tricks________________________9
Block diagram____________________--10
Installation________________________10
__
Maintenance_________________________
11
Specifications_____________________ 12
Warranty_________________________13-15
www.signal-audio.com
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Dear customer,
I’d like to personally thank you for the confidence
that you have shown in Signal Audio Workshop
by purchasing the CH2-M. You acquired the latest
generation of Microphone pre amp which is
unequal in its design and specification.
I am confident that working with the CH2-M will
open new worlds of manipulating audio signals
with a tool like no other. In order to produce the
full potential of this sophisticated tool I strongly
encourage you to read and understand this manual thoroughly.
The CH2-M is truly a unique piece of equipment with Tube heart
and analog soul.
Every piece of gear Signal AWS makes is meticulously hand
crafted in our workshop. We consider the development and
assembly as a form of art and take great pride in the final
product.
The CH2-M is a result of a two year development period in which
we researched the fundamentals of Microphone pre amps
topologies, in an effort to innovate and achieve the CH2-M
outstanding Sonic capabilities.
For the input stage we designed a custom Mu-metal input
transformers for maximum signal linearity along with the sonic
benefits of the transformer’s character. We specially designed a
Tube CLASS A input stage for its second harmonic performance
in order to match the needs of digital recording to the warm
sound of analog equipment.
All signal path stages are pure CLASS-A with tubes circuitry and
transformers for each channel take this uncompromising
structure to the highest level of sonic excellence.
These features make this revolutionary tool out stand any other
in today’s market!
I hope you will enjoy working with the CH2-M as much as
we enjoyed making it for you!
With Honor.
Oded Levy
Signal AWS
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Front panel controls:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
48v phantom switch.
Phase reverse switch.
-20db pad (reduction of high level input signals).
Input select switch – selects input source
microphone/DI.
Direct input specially designed for high impedance
sources (input impedance 4.7m).
Tube gain knob from +22db to 60db.
H.P.F. selectable five frequency rotary switch –
changes low cut frequencies at 12db/oct.
Power Standby switch.
Tube filaments light indicator.
+300v power light indicator.
Source select switch: selects between three input
sources A, B, C, & cut.
Control room level: main rotary fader for control room
monitors.
Monitor select switch: toggles between
main/alternative monitors.
Dim switch: dims the control room level for fine mix
balance adjustments.
Mono switch: selects control room monitoring between
mono/stereo mode.
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Rear panel:
Rear panel elements:
4 XLR balanced line input/output
connectors with the same pin standard
as shown in the diagram.
Mains voltage 220/115 VAC input select
switch. Mains power socket with mains
fuse.
PIN1 GND
PIN2 HOT
PIN3 COLD
Construction options:
12 step rotary gain selector (optional):
12 step rotary gain selector optional
with 3.3db steps constructed with metal
film 1% resistors and sealed rotary
selectors with silver coated contacts.
EXTERNAL TALKBACK SECTION
(OPTIONAL):
Features:
Talkback switch: enables momentary talkback to
the headphone system.
Talkback microphone gain knob.
Talkback microphone.
Talkback unit I/O connectors: unbalanced stereo
T.R.S. enables talkback breakthrough on headphone feed (between
the DAW and HF amplifier).
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T.B. unit block diagram:
Signal chain:
This chapter details on the signal chain’s structure in order to help
you better understand the CH2-M.
(1)
INPUT SECURITY:
Designed for maximum optimization of all microphones with
all standard features like +48v (phantom), phase reverse
switch and -20db pad, especially designed for minimum sonic
degradation. All these functions are preformed with special
silver coated toggle switches for maximum rigidness of
operation.
(2)
INPUT TRANSFORMER:
High gain 200 ohm microphone input transformer matching to
a high input impedance. Design for optimal reduction of most
kinds of noise caused when microphones are connected.
Ensure Electromagnetic Compatibility (EMC) standards
compliance. Feature Mu-metal core for minimal harmonic
distortion. Internal electrostatic shields for maximum common
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mode noise rejection at high frequencies. Multiple interleaved
windings ensure low leakage inductance for excellent ultra
high frequency response. Mu-metal can for magnetic
shielding.
(3)
TUBE GAIN STAGE:
Vacuum tube class A topology gain amplifier ranges from
+22db to 62db (typical). Designed especially to deliver a
constant sonic performance at all gain levels. This stage was
especially tailored to preserve the delicate balance between
transparency and 2nd harmonic THD. An optional 12 step
rotary gain selector can be added with 3.3db steps, made with
metal film 1% resistors and silver coated contacts.
(4)
PASSIVE HIGH PASS FILTER:
12db/oct passive H.P.F. filter with five cutoff frequencies and
hard wired bypass. Cutoff frequencies are 65, 110, 180, 250,
450 Hz. All frequencies filter electronics made from passive
components with audio grade capacitors in order to preserve
sonic excellence.
(5)
OUTPUT STAGE:
Design to deliver a delicate balance between signal
transparency and tube second harmonics. This stage was
carefully tailored to provide all advantages of both tube
oriented warm sound and solid state signal transparency.
Highest grade of solid state electronics with +/-24v power
supply. Transparently delivers full advantages of all previous
stages.
All signal stages are made from metal film resistors and audio
grade capacitors to preserve maximum sonic performance.
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Psu 15 power supply:
The Psu 15 unit is an all
discrete CLASS A topology,
made with massive
filterazation, designed
especially for the lowest noise
floor needed in microphone
amplifying.
For a fact: Pre amps noise
floor is constructed from the
amp’s self noise + its Psu
noise floor.
Therefore noise floor issue is very important when dealing
with a 60db gain machine. This is why we engineered an
uncompromising Psu that is suitable to deliver an ultra low
noise floor.
Features:
+300 vdc B+ voltage highly regulated for tube plates.
+50.4 vdc voltage for tube filaments (regulated).
+48 vdc phantom power (regulated).
+/-24 vdc for vcc to solid state electronics (regulated).
The Psu 15 can be internally modified for 220 or 115
vac operation (must be preformed by qualified
technician!).
Always make sure that the unit operates on the
correct mains voltage (230/115 VAC) before
applying mains voltage!
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Tips & Tricks:
1. stereo recording: one of the most common methods of recording
stereo signals is done by locating two identical microphones in an
x/y mode and the calibration of the gain should be done by the
following steps:
A. Calibrate channel 1 gain to optimum
recording level by viewing the “in level”
meter on your recorder.
B. Repeat step A on channel 2.
C. Reverse the phase on channel 2.
D. Press mono on your control room
monitoring system.
E. Re trim the gain on channel 2 to maximize phase cancellation
between the two sides.
F. Return to normal phase and stereo mode.
2. As a rule of thumb: calibrate record level will be done by viewing
the recording level of the recorder and not other meters that may
be on the recording chain (such as compressor etc`).
3. Some microphones may produce very high output level,
therefore we recommend using the -20db pad switch, in cases of
high S.P.L. recorded otherwise the channel may clip while
recording.
4. Cutting environmental rumbles with the 65 Hz H.P.F. on male
vocals is preferably done even without compensating low
frequency with external EQ by wisely manipulating the proximity
effect of cardioid microphones.
5. M-S recording technique: place 3 microphones (center, left &
right) according to the diagram:
Reverse phase on left microphone.
Combine the three microphones on your
mixer. The sides channels should be hard
panned L<>R, and center panned to the
center. The center microphone level in the
resulted mix will affect the stereo images
width
according to the balance between sides and center microphones.
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Control Room Block Diagram:
This chapter details the signal chain structure in order to help
you better understand the control room section functions.
All signal stages are passive and unbalanced.
Installing the unit:
Always install this unit in a properly grounded environment!
Do not expose the unit to humidity or dusty environment!
Do not expose the unit to heat sources and unventilated places!
Always make sure that the unit operates on the correct mains
voltage (230/115 VAC) before applying mains voltage!
Signal AWS will not be responsible for damages created by
improper mains voltage issues.
All audio connections in the
preamp section are balanced
threw XLR connectors with the pin
shown list:
PIN1
GND
PIN2
HOT
PIN3 COLD
Control Room section ¼” Connection Diagram:
Sleeve
Ground
Tip
Signal
When connecting unbalanced signals to balanced connections and
vice versa, the connection will be done according to standard.
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Maintenance:
Cleaning:
Do not clean the unit with water or with water soaked cloth.
Cleaning is best made with dry dusting brush and vacuum cleaner.
Dust and moisture are the primer enemy of switches and contacts
within this unit. Avoiding them as much as you can will prolong the
unit’s life significantly.
Maintenance:
There are no user’s serviceable parts inside the unit.
Opening and servicing this unit by someone who is not authorized by
Signal AWS is strictly prohibited.
Technical service is made only by those who are authorized from
Signal AWS.
We recommend replacement of vacuum tubes only when
The unit has proven to not function correctly and according to
the type of problem discovered.
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Specifications
Electronics structure (from in to out):
Phantom power (+48 V) switches.
Phase reverse & -18db pad switches.
Custom 200 ohm microphone input step-up transformers in
Mumetal cases.
12AX7 tubes CLASS A design 62db gain amplifier.
Fully passive 12db/oct 5-state high-pass filters + bypass.
Filter frequencies: 65Hz, 110Hz, 180Hz, 250Hz & 450Hz.
Solid state transformerless design balanced output stage.
Input Impedance:
Output Impedance:
MAX Gain:
MAX Input level:
MAX Output level:
Noise Floor:
Frequency Response:
Gain:
Operating Voltage:
Fuse Type:
200 Ohms Balanced, (PIN 2 HOT).
>50 Ohms Balanced, (PIN 2 HOT).
62 db (typical).
+2dbm (for THD < 2%).
+31dbm/600 ohm (on balanced output).
-70db @ 22-22khz (typical).
20-20kHz +/- 0.3db, 15-40kHz +/2db.
62db continuously variable from +22
to +62db.
230Vac @ 50Hz / 115Vac @ 60Hz.
2 Amp slo-blo for 120 Volt mains.
1 Amp slo-blo for 230 Volt mains.
External massive regulated power supply unit.
Output voltages:
Operating Voltage:
+300 vdc,+50.4 vdc,+48 vdc,+/-24 vdc
230Vac @ 50Hz / 115Vac @ 60Hz.
Dimensions CH2-M:
H= 3 units, W= 19”,D=5”.
Dimensions Psu-15:
W=5.5”, H=4”, D=11”
Shipping weight:
All spec’s at RL=600Ohm.
Info subject to change without prior notice!
All legal rights reserved to Signal Audio Workshop!
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Limited Warranty
This product is warranted to the original consumer purchaser to be free from defects in
materials and workmanship under normal installation, use and service for a period of
one (1) year from the date of purchase as shown on the purchaser’s receipt.
The obligation of Signal Audio Workshop under this warranty shall be limited to repair
or replacement (at our option), during the warranty period of any part which proves
defective in material or workmanship under normal installation, use and service,
provided the product is returned to Signal Audio Workshop, TRANSPORTATION
CHARGES PREPAID. Products returned to us or to an authorized Service Center must
be accompanied by a copy of the purchase receipt. In the absence of such purchase
receipt, the warranty period shall be one (1) year from the date of manufacture. This
warranty shall be invalid if the product is damaged as a result of defacement, misuse,
abuse, neglect, accident, shipping damage destruction or alteration of the serial
number, improper electrical voltages or currents, repair, alteration or maintenance by
any person or party other than our own service facility or an authorized Service Center,
or any violation of instructions furnished by us. This one-year warranty is in lieu of all
expressed warranties, obligations or liabilities.
ANY IMPLIED WARRANTIES, OBLIGATIONS, ORLIABILITIES, INCLUDING BUT
NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICU-LAR PURPOSE, SHALL BE LIMITED IN DURATION TO
THE ONE YEAR DURATION OF THIS WRITTEN LIMITED WARRANTY. Some states
do not allow limitations on how long an implied warranty lasts, so the above limitation
may not apply to you. IN NO EVENT SHALL WE BE LIABLE FOR ANY SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES FOR BREACH OF THIS OR ANY
OTHER WARRANTY, EXPRESSED OR IMPLIED, WHATSO-EVER.
Some states do not allow the exclusion or limitation of special, incidental or
consequential damages so the above limitation or exclusion may not apply to you. This
warranty gives you specific legal rights, and you may also have other rights which vary
from state to state.
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Warranty registration form
Please take the time to fill out this registration Form and send it to
the address mentioned below. Or send this page threw e-mail to:
info@signal-audio.com
Signal Audio Workshop
53 Abarbanel ST.
Tel Aviv 66089 Israel
P.O.B 5169 TLV 61051
Or send it by Fax: 972-3-6824716
Registering your product will allow you to get full warranty service
plus product upgrades if there will be any at the warranty period,
according to Warranty rules.
We would like to seize these opportunity to thank you once again
for choosing Signal AWS as your product leader.
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Comments:
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