Operating Instruction Manual
POWERED MIXER
Model MX-401
Toa Electric Co., Ltd.
KOBE, JAPAN
Contents
General Description
2
Features
2
Front Panel [Names of components & their usage]
3
Rear Panel [Names of components & their usage]
4
Connection Examples
5
Input Connections
6
Block and Level Diagrams
7
Specifications
8
Characteristics Diagrams
9
Appearance
9
Precautions
1. XLR Type Audio Connector
The connectors are wired as follows.
The pin 1 is ground (shield), the pin 2 cold (low, minus), the pin 3 hot (high, plus).
2. Description of components and functions on the MX-401.
Various descriptions are applied, depending on each manufacturer. In our
Operating and Instruction Manual explanation of components and functions is
made according to our usage for them.
General Description
The TOA MX-401 is a very compact, four channel self-powered mixer. It was
designed to deliver maximum features and performance in a cost-effective portable
PA package.
The MX-401 features four input channels, one program output, and one Foldback
output. The internal amplifier is rated at 100 watts into an 8 ohm load, and 150 watts
into 4 ohms.
Each input channel has an electronically balanced XLR connector, and a highimpedance unbalanced 1/4" phone jack. In addition, each channel features two-band
EQ, a pre-EQ Foldback send, and post-EQ reverb send.
The master control section features a patchable 5-band graphic equalizer, a quality 3spring reverb, a full patch bay with 1/4" phone auxiliary and RCA tape inputs, and
master volume controls for Program, Foldback, and Reverb return to both. The power
amp protection circuitry and autocomp compressor, both with LED's, are also located
in this section.
Features
1. Four input channels
2. 100 watts into 8 ohms, 150 watts into 4 ohms
3. Patchable 5-band graphic EQ
4. Auto Comp compression unit w/LED
5. Built-in spring reverb
6. Power amp protection circuitry w/LED
7. Full patch bay
8. Aux input w/level control, RCA jacks and parallel phone 1/4" jacks.
9. Reverb level to PGM and FB
10. Independent Foldback mix.
Each Channel
1. Input level control
2. Two band EQ
3. Pre-EQ Foldback send
5. Low-Z electronically balanced XLR input
6. Hi-Z unbalanced 1/4" input
— 2—
Front Panel
High Equalizer Control
(HIGH)
The high EQ control alters t h e
high frequency response of the
input channel, providing ±13dB
at 10kHz, and ±15dB at 20kHz of
continuously variable active
shelving equalization. The "0"
detented position provides flat
audio response.
Low Equalizer Control
(LOW)
The low EQ control provides
±13dB at 100Hz and ±15dB at
50Hz of continuously variable
active shelving equalization.
The "0" detented position provides flat audio response.
Input Level Control
(LEVEL)
The level control provides continuously variable a d j u s t m e n t
of the channel o u t p u t to the
program mixing buss, t h u s
determining the level of t h a t
channel in t h e main sound
system mix. Since t h e reverb
signal is "post" this control, an
increase in the level of the
channel's o u t p u t will also result
in a corresponding increase in
the reverb effect of t h a t channel.
The nominal level of t h e i n p u t
level control is at t h e "10" position.
High Impedance Connectors
(HIGH Z)
These connectors are unbalanced, standard 1/4" phone jacks
with an input impedance of 27k
ohms, and an input level of
—35dB. When a plug is inserted
into the high -Z i n p u t , the corresponding XLR connector is
automatically switched out of the
input circuitry.
Low Impedance Connectors
(LOW Z)
The XLR connectors are low impedance, electronically balanced
inputs with an input impedance
of 1k ohms.
Graphic Equalizer
(EQUALIZATION)
The graphic equalizer is 5 independent active bands ( f i l t e r s ) ,
providing 12dB of boost or cut at
each center frequency. The "0"
detented p o s i t i o n provides f l a t
audio response.
Reverb to Foldback
Control (REV TO FB)
This control adjusts the amount
of reverb signal that is returned
to the foldback buss and thus t h e
level of reverb contained in t h e
on-stage monitor mix.
Reverb/Control
(REV)
This control determines t h e
level of signal assigned to the reverb mixing buss. R o t a t i n g the
control clockwise increases the
amount of reverb in that channel.
Foldback Master Control (FB)
The FB master control a d j u s t s
the overall combined signal level
of the four independent channel
foldback sends, and thus the
level of the entire on-stage monitor mix.
Foldback Control (FB)
The Foldback control determines the level of signal assigned to the foldback mixing buss,
t h u s s e t t i n g the level of t h a t
channel in the on-stage m o n i t o r
mix.
Aux Level Control (AUX)
This control sets the overall level
of the Aux i n p u t signal.
Power Amp Compression
Indicator
(COMP)
The Comp LED l i g h t s when the
internal compressor is activated.
The compressor is provided to
protect speaker systems by compressing the input signal level of
the power amplifier when clipping occurs in the o u t p u t stage.
Frequent flashing of the LED is
not reason for alarm. However, a
constant or steady light indicates
t h a t the MX-401 is being overdriven and that the internal
power amplifier is possibly
"under powered" for that application. The o u t p u t level of the MX401 should be decreased u n t i l the
LED only flashes i n t e r m i t t e n t l y .
Power Indicator LED
(POWER)
The i n d i c a t o r LED l i g h t s when
t h e power switch is "on".
Reverb to Program Control
(REV TO PGM)
This control adjusts the amount
of reverb signal t h a t is r e t u r n e d
to t h e program buss and t h u s the
level of reverb contained in t h e
main sound system.
Graphic Equalizer Input Jack
(GEQ IN)
The GEQ i n p u t jack allows t h e
graphic equalizer to be used ind e p e n d e n t l y of t h e MX-401 w i t h
other e x t e r n a l e q u i p m e n t , or t h e
i n t e r n a l power a m p l i f i e r and t h e
graphic equalizer w i t h e x t e r n a l
e q u i p m e n t . When a plug is
inserted, the main mix f r o m
t h e program buss is d i s c o n n e c t e d
from t h e graphic e q u a l i z e r and
the power a m p l i f i e r . The nominal i n p u t level is +4dB w i t h an
i n p u t impedance of 50k ohms.
Power Amp Protection
Indicator (PROTECT)
The i n d i c a t o r LED lights if t h e
power a m p l i f i e r o u t p u t is shorted, if t h e t e m p e r a t u r e of the u n i t
rises above acceptable levels, or
if DC is d r i f t e d to the speaker
o u t p u t s . I f the LED should l i g h t ,
speaker w i r i n g and a m b i e n t
t e m p e r a t u r e of t h e MX-401
should be checked. If t h e LED
remains l i g h t e d , t h e u n i t should
be referred to q u a l i f i e d service
personnel for repair.
Note:
The MX-401 p r o t e c t i o n c i r c u i t r y
will (1) detect ' f a u l t y conditions'
w i t h i n the power a m p l i f i e r , (2)
give a v i s u a l i n d i c a t i o n , and (3)
a u t o m a t i c a l l y s h u t down u n t i l
t h e f a u l t condition is alleviated.
This special c i r c u i t r y ensures
m a x i m u m r e l i a b i l i t y and virtually eliminates equipment
damage due to u n s a f e or f a u l t
conditions. Please refer to f a u l t
p r o t e c t i o n t a b l e on page 4 for
f u l l e x p l a n a t i o n of this important feature.
Graphic Equalizer Output Jack
(GEQ OUT)
This j a c k allows t h e MX-401
and t h e i n t e r n a l g r a p h i c e q u a l izer to be used w i t h an e x t e r n a l
power a m p l i f i e r , or in c o n j u n c t i o n w i t h t h e GEQ in j a c k , to be
used i n d e p e n d e n t l y of all o t h e r
MX-401 c i r c u i t r y . N o m i n a l
o u t p u t l e v e l is +4dB w i t h an
i m p e d a n c e of 600 ohms.
Power Amplifier Input Jack
(PWR IN)
The PWR Amp i n p u t jack allows
t h e i n t e r n a l power a m p l i f i e r to
be used w i t h e x t e r n a l equipm e n t . When a plug is i n s e r t e d ,
t h e p o w e r amp is a u t o m a t i c a l l y
d i s c o n n e c t e d f r o m t h e MX-401
m i x e r section. The nominal inp u t level is +4dB w i t h an i n p u t
i m p e d a n c e of 10k ohms.
Program Output Jack
(PGM OUT)
The PGM Out jack is provided
for c o n n e c t i o n t o e x t e r n a l equalizers and/or power amps, d e r i v ing i t s signal prior to the i n t e r n a l
GEQ and power amp. N o m i n a l
o u t p u t level is +4dB w i t h an
impedance of 600 ohms.
Program Master Control
(PGM)
The PGM control a d j u s t s the
overall combined signal level of
t h e f o u r independent c h a n n e l
level controls, and thus the level
of t h e main sound system.
Aux Input Jacks
(AUX IN)
The phone j a c k and RCA pin
jacks are wired in parallel, with
an i n p u t level of —20dB. When a
plug is inserted i n t o the phone
j a c k , the RCA pin jacks are
a u t o m a t i c a l l y switched out of
the AUX circuitry.
Foldback Output Jack
(FB OUT)
This j a c k is for c o n n e c t i o n to
external power amplifiers and/
or equalizers for the on-stage
m o n i t o r i n g system. N o m i n a l
o u t p u t level is +4dB w i t h an
impedance of 600 ohms. If t h e
internal power amp and equalizer are to be used for t h e onstage monitor system, the FB
o u t p u t should be connected to
the GEQ input jack.
—
3—
Rear Panel
Power Switch (POWER)
The power switch is a threeposition type with the middle
position being the "off position.
The MX-401 should be operated
in the switch position which
produces the lowest amount of
system hum.
Cord Wrap
The cord wrap is provided for
c o n v e n i e n t storage of t h e power
cord when t h e MX-401 is not in
use.
Caution - The power cord should
always be c o m p l e t e l y removed
f r o m t h e cord wrap prior t o
o p e r a t i o n of t h e u n i t . This will
i n s u r e m a x i m u m cooling of t h e
MX-401 For t h e same reason,
a d e q u a t e clearance should be
m a i n t a i n e d between t h e rear
panel and any o t h e r surface (4-6
inches should do). The v e n t s on
t h e b o t t o m and t o p of the MX401 are also provided for convect i o n cooling. These v e n t s should
be k e p t clear and open. Failure t o
do so may cause t h e r m a l s h u t down of t h e u n i t .
Speaker Jacks (SPEAKERS)
The speaker o u t p u t s are standard 1/4" phone jacks wired in
parallel. Speaker cables (recommend at least #18 gauge wire)
should be connected between
the MX-401 and the speaker
systems prior to applying power
to the unit.
Caution - The MX-401 should
never be operated into less t h a n
a 4 ohm speaker load.
Earth Terminal (GND)
AC Fuse
AC Power Cord
The power cord is the three-wire
type w i t h proper grounding facilities.
Caution - The ground pin should
not be removed under any circumstances. If t h e MX-401 must
be used w i t h o u t proper grounding facilities, a suitable grounding adapter should be u t i l i z e d .
Operation of the MX-401 w i t h
proper grounding techniques
will result in less system noise
and greatly reduced shock
hazard.
Warning - To avoid possible
e q u i p m e n t damage and/or personnel i n j u r y , t h e fuse s h o u l d
a l w a y s be replaced w i t h same
t y p e and r a t i n g . Using improper
fuses w i l l also void t h e warrant y . The MX-401 s h o u l d a l w a y s
be d i s c o n n e c t e d f r o m AC o u t l e t
prior t o changing fuses. If fuse
r e p e a t e d l y f a i l s , t h e u n i t should
be referred t o q u a l i f i e d service
personnel for repair.
Fault Protection Table
Fault
Protection
Indication
Action
Restoration
Excessive current due to
overloads.
Current limiter activates at
less than 2 ohm.
Compressor
LED illuminates.
Remove excessive loads.
Minimum speaker loads
4 ohm.
Automatic restoration
after normal loads are
obtained.
Short circuits
(less than 0.4-ohm)
Current limiter activates,
input signal is lowered,
unit shuts down.
Amp protection
LED illuminates.
Check speaker
lines/systems for shorts.
Turn off power switch.
Turn on into operational
loads.
Temperature rise of heat
sink
(more than 105°C)
Input signal is lowered.
Unit shuts down.
Amp protection
LED illuminates.
Check for adequate
ventilation.
Automatic restoration
after temperature
lowers ( t o 75° - 95° C)
DC drift
Input signal is lowered.
Unit shuts down.
Amp protection
LED illuminates.
Refer to qualified service
personnel.
Automatic restoration
a f t e r normal bias is
regained.
—
4—
Connection Examples
SPEAKER SYSTEM
for foldback
MAIN SPEAKER SYSTEM
(Self powered speakers)
From Speaker J a c k
on Rear Panel
Line O u t
KEYBOARD
Low Z i n p u t should be connected
w i t h low impedance (50 ohm ~ 600 ohm)
microphones
CASSETTE TAPE DECK
for playback
Line Out
MUSICAL INSTRUMENT
— 5—
Input Connections
Generally speaking, there are two rules to follow when connecting equipment o u t p u t s
to the inputs of other equipment.
1. Properly match the impedances of the outputs and inputs.
2. Connect low impedance outputs to high impedance inputs.
It goes without saying that not only input and o u t p u t impedance matching, but also
level matching should be taken into consideration. Each input channel of the MX-401
is provided with an Input Level Control that includes a negative feedback (NF)
circuitry, so the usable signal level range is wide. Input impedances and levels are
shown in the following table.
INPUT SPECIFICATIONS
CONNECTION
INPUT
ACTUAL
LOAD
IMPEDANCE
CH1
LOW Z
OPEN
CH4
HIGH Z
27k
FOR USE
WITH
NOMINAL
50
SENSITIVITY*
(PGM OUTPUT
LEVEL +4dB)
CONNECTOR
-60dB (0.78mV)
XLR TYPE NC3F
-35dB (13.8mV)
PHONE J A C K
TO 250
MICROPHONES
27k OR
LOWER IMP
LINES
AUX
30k
30k OR
LOWER IMP,
LINES
-20dB (77.5mV)
RCA PIN JACK
PHONE JACK
GEQ
50k
50k OR
LOWER IMP,
LINES
+4dB (1.23V)
PHONE JACK
PWR/AMP
10k
10k OR
LOWER IMP,
LINES
+4dB (1.23V)
PHONE J A C K
*Sensitivity is the level required to produce a program out level of +4dB.
*0dB is referenced to 0.775V RMS.
All XLR Type connectors are electronic balanced. Phone jack is unbalanced.
If the line going from one piece of equipment to another is long (more t h a n 5m), we
recommend that balanced outputs be connected to balanced inputs.
As is described in the beginning of the Operating Instructions Manual, t h e connectors
of the MX-401 are wired as follows: Pin 1 is ground (shield). Pin 2 is cold (low, m i n u s ) .
Pin 3 is hot (high, plus).
—
6—
Block and Level Diagrams
BLOCK DIAGRAMS
LEVEL DIAGRAM
—
7—
Specifications
MIXER SECTION
Maximum Voltage Gain
INPUT to PGM o u t
INPUT t o FB o u t
INPUT t o GEQ o u t
AUX t o PGM o u t
Frequency Response
+0, -3dB 60Hz~20kHz ( i n p u t LEVEL at "5" p o s i t i o n )
Total Harmonic Distortion
0.05% +4dB* at 1kHz.
64dB
64dB
64dB
24dB
Input EQ
50Hz ±15dB S h e l v i n g
20kHz ±15dB Shelving
Hum and Noise (Open)
E q u i v a l e n t I n p u t Noise
-130dB* (20Hz ~ 20kHz)
E q u i v a l e n t I n p u t Noise
-133dB* (IHF A)
All level Controls M i n i m u m
-110dB* (IHF A)
PGM Master a t MAX and all
i n p u t level c o n t r o l s m i n i m u m -90dB* (IHF A)
PGM Master a t MAX and one
i n p u t level c o n t r o l at MAX
-70dB* (IHF A)
Equalization
63Hz ±12dB P e a k i n g
250kHz ±12dB P e a k i n g
1kHz ±12dB Peaking
2 k H z ±12dB P e a k i n g
8kHz ± 1 2 d B Peaking
INPUT SPECIFICATIONS
SENSITIVITY*
(PGM OUTPUT
LEVEL +4dB)
CONNECTOR
-60dB (0.78mV)
XLR TYPE NC3F
27k OR
LOWER IMP
LINES
-35dB (13.8mV)
PHONE JACK
30k
30k OR
LOWER IMP,
LINES
-20dB (77.5mV)
RCA PIN JACK
P H O N E JACK
GEQ
50k
50k OR
L O W E R IMP,.
LINES
+4dB ( 1 . 2 3 V )
P H O N E JACK
PWR/AMP
10k
10k OR
LOWER IMP,
LINES
+4dB (1.23V)
PHONE JACK
CONNECTION
INPUT
ACTUAL
LOAD
IMPEDANCE
CH1
LOW Z
OPEN
CH4
HIGH Z
27k
AUX
FOR USE
WITH
NOMINAL
50
TO 250
MICROPHONES
OUTPUT SPECIFICATIONS
CONNECTION
ACTUAL
SOURCE
IMPEDANCE
PGM
600
GEQ
600
FB
600
FOR USE WITH
NOMINAL
OR HIGHER
IMP. LINES
600 OR HIGHER
IMP. LINES
600 OR HIGHER
IMP. LINES
600!
NOMINAL
OUTPUT LEVEL*
MAX. BEFORE
CLIP
CONNECTOR
+4dB (1.23V)
+20dB (7.75V)
PHONE J A C K
+4dB (1.23V)
+20dB (7.75V)
P H O N E JACK
+4dB (1.23V)
+20dB (7.75V)
PHONE JACK
POWER AMPLIFIER SECTION
Frequency Response
+0, -1dB 15Hz to 30k Hz (150W RMS 4
Rated Power & Load
150W RMS (4 ) 110W RMS (8 )
Power Output at Clipping
1% THD, 1kHz
160W RMS (4 ) 115 W RMS ( )
Total Harmonic Distortion
Less than 0.1% (200mW ~150W RMS, 20Hz~20kHz, 4
Typically below 0.05%
Compresser Dynamic Range
Greater t h a n 26dB
Hum and Noise
At least 105dB S/N r a t i o , 20Hz~20kHz
At least 109dB S/N r a t i o IHF-A w e i g h t e d
Damping Factor
Greater t h a n 200 [1kHz 8 )
)
Input Sensitivity
+4dB* (1.23V)
Input Impedance
10k
Output Connector
Phone Jack ×2
Power Requirement
300W
Dimensions
494(W) × 180(H) × 304(D) (19.44 × 7.09 × 11.97) ins.
Weight
10 kg (22 lbs)
*0dB is referenced to 0.775V RMS.
*Specifications are subject to change without notice.
Characteristics Diagrams
LOW Z HIGH Z IN & INPUT EQ (LEVEL Control)
HIGH Z IN. & INPUT EQ (set at "5")
GEQ
POWER AMP POWER BAND WIDTH
POWER AMP T.H.D. vs POWER OUTPUT
POWER AMP COMPRESSOR
REVERBERATION FREQUENCY RESPONSE
Appearance
494 (19.44")
180 (7.09")
304 (11.97")
—
9—
Toa Electric Co., Ltd.
KOBE, JAPAN
Printed in Japan
133-02-873-5
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