Page 1
POWERED MIXER
Model MX-401
Operating Instruction Manual
Toa Electric Co., Ltd.
KOBE, JAPAN
Page 2
Contents
General Description
Features
Front Panel [Names of components & their usage]
Rear Panel [Names of components & their usage]
Connection Examples
Input Connections
Block and Level Diagrams
Specifications
Characteristics Diagrams
Appearance
2
2
3
4
5
6
7
8
9
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.
Page 3
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
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Page 4
Front Panel
High Equalizer Control
The high EQ control alters the
high frequency response of the
input channel, providing ±13dB
at 10kHz, a nd ±15dB at 20 kHz of
continuously variable active
shelving equalization. The "0"
detented position provides flat
audio response.
Low Equalizer Control
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.
(HIGH)
(LOW)
Reverb to Foldback
This control adjusts the amount
of reverb signal that is returned
to the foldback buss and thus the
level of reverb contained in the
on-stage monitor mix.
Reverb/Control
(REV)
This control determines the
level of signal assigned to the reverb mixing buss. Rotating the
control clockwise increases the
amount of reverb in that channel.
Foldback Control (FB)
The Foldback control determines the level of signal assigned to the foldback mixing buss,
thus setting the level of t ha t
channel in the on-stage monitor
mix.
Control (REV TO FB)
Graphic Equalizer
The graphic equalizer is 5 independent active bands (filters),
providing 12dB of boost or cut at
each center frequency. The "0"
detented position provides f lat
audio response.
Foldback Master Control (FB)
The FB master control adjusts
the overall combined signal level
of the four independent channel
foldback sends, and th us the
level of th e entire on-stage moni-
tor
mix.
Aux Level Control (AUX)
This control sets the overall level
of the Aux input signal.
(EQUALIZATION)
Power Amp Compression
Indicator
(COMP)
The Comp LED lights 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 outp ut stage.
Frequent flashing of the LED is
not reason for alarm. However, a
constant or steady light indicates
that the MX-401 is being overdriven and that the internal
power amplifier is possibly
"under powered" for that application. The output level of the MX401 should be decreased u nt il the
LED only flashes intermittently.
Power Indicator LED
(POWER)
The indicator LED lights when
the pow er sw it ch is "on".
Input Level Control
The level control provides continuously variable a djustment
of the channel output to the
program mixing buss, thus
determining the level of that
channel in the main sound
system mix. Since th e reverb
signal is "post" this control, an
increase in the level of the
channel's output will also result
in a corresponding increase in
the reverb effe ct of tha t channel.
The nominal level of the input
level control is at the "10" position.
High Impedance Connectors
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 input, the corresponding XLR connector is
automatically switched out of the
input circuitry.
Low Impedance Connectors
The XLR connectors are low impedance, electronically balanced
inputs with an input impedance
of 1k ohms.
(LEVEL)
(HIGH Z)
(LOW
Z)
Reverb to Program Control
This control adjusts the amount
of reverb signal that is ret urn ed
to the program buss and thus the
level of reverb contained in the
main sound system.
The PGM control adjusts the
overall combined signal level of
the four independent channel
level controls, and thus the level
of the main sound system.
The phone jack and RCA pin
jacks are wired in parallel, with
an input level of —20dB. When a
plug is inserted into the phone
jack, the RCA pin jacks are
automatically switched out of
the AUX circuitry.
This jack is for connection to
ext erna l power amplifiers and/
or equalizers for the on-stage
monitoring system. Nominal
output level is +4dB w ith an
impedance of 600 ohms. If the
internal power amp and equalizer are to be used for th e on-
stage monitor system, the FB
output should be connected to
the GEQ input jack.
(REV
TO
PGM)
Program Master Control
Aux Input Jacks
Foldback Output Jack
(PGM)
(AUX
(FB
IN)
OUT)
Program Output Jack
(PGM
OUT)
The PGM Out jack is provided
for connection to external equalizers and/or power amps, deriving its signal prior to the internal
GEQ and power amp. Nominal
output level is +4dB w it h an
impedance of 600 ohms.
Graphic Equalizer Input Jack
(GEQ
IN)
The GEQ input jack allows the
graphic equalizer to be used independently of the
other external equipment, or the
internal power amplifier and the
graphic equalizer with externa l
equipment. When a plug is
inserted, the main mix from
the program buss is disconnected
from the graphic equalizer and
the power amplifier. The nominal input level is +4dB wi th an
input impedance of 50k ohms.
Graphic Equalizer Output Jack
(GEQ
OUT)
This jack allows the MX-401
and the internal graphic equalizer to be used with an external
power amplifier, or in conjunction with the GEQ in jack, to be
used independently of all other
MX-401 circuitry. Nominal
output level is +4dB w ith an
impedance of 600 ohms.
MX-401
with
Power Amp Protection
Indicator (PROTECT)
The indicator LED lights if th e
power amplifier output is shorted, if the temperature of the unit
rises above acceptable levels, or
if DC is drifted to the speaker
ou tputs . I f the LED should lig ht ,
speaker wiring and ambient
temperature of the MX-401
should be checked. If the LED
remains lighted, the unit should
be referred to qualified service
personnel for repair.
Note:
The MX-401 protection circuitry
will (1) detect 'faulty conditions'
within the power amplifier, (2)
give a visual indication, and (3)
automatically shut down until
the fau lt condition is alleviated.
This special circuitry ensures
maximum reliability and virtually eliminates equipment
damage due to unsafe or fault
conditions. Please refer to faul t
protection table on page 4 for
full explanation of this important feature.
Power Amplifier Input Jack
(PWR
IN)
The PWR Amp input jack allows
the internal power amplifier to
be used with external equipment. When a plug is inserted,
the power amp is automatically
disconnected from the MX-401
mixer section. The nominal input level is +4dB with an input
impedance of 10k ohms.
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Page 5
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.
Speaker Jacks (SPEAKERS)
The speaker outpu ts are stand-
ard 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 than
a 4 ohm speaker load.
Earth Terminal (GND)
The power cord is the three-wire
type with proper grounding faci-
lities.
Caution - The ground pin should
not be removed under any circumstances. If the MX-401 must
be used without proper grounding facilities, a suitable ground-
ing adapter should be utilized.
AC Power Cord
Operation of the MX-401 with
proper grounding techniques
will result in less system noise
and greatly reduced shock
hazard.
AC Fuse
Cord Wrap
The cord wrap is provided for
convenient storage of the power
co rd when the MX-401 is no t in
use.
Caution - The power cord should
always be completely removed
from th e cord wrap prior to
operation of the uni t. This will
insure maximum cooling of the
MX-401 For th e same reason,
adequate clearance should be
maintained between the rear
panel and any other surface (4-6
inches should do). The vents on
the bottom and top of the MX401 are also provided for convec-
tion co oling . These ve nt s should
be k ept clear and open. Failure to
do so may cause t her mal shu t-
down of the unit.
Warning - To avoid possible
equipment damage and/or personnel i nj ur y, th e fuse should
always be replaced with same
type and rating. Using improper
fuses will also void the warran-
ty. The MX-401 should always
be disconnected from AC outlet
prior to changing fuses. If fuse
repeatedly fails, the unit should
be referred to qualified service
personnel for repair.
Fault
Excessive current due to
overloads.
Short circuits
(less than 0.4-ohm)
Temperature rise of heat
sink
(m ore than 105°C)
DC drift
Fault Protection Table
Protection
Current limiter activates at
less than 2 ohm.
Current limiter activates,
input signal is lowered,
unit shuts down.
Input signal is lowered.
Unit shuts down.
Input signal is lowered.
Unit shuts down.
Indication
Compressor
LED illuminates.
Amp protection
LED illuminates.
Amp protection
LED illuminates.
Amp protection
LED illuminates.
Action
Remove excessive loads.
Minimum speaker loads
4
ohm.
Check speaker
lines/systems for shorts.
Check for adequate
ventilation.
Refer to qualified service
personnel.
Restoration
Automatic restoration
after normal loads are
obtained.
Turn off power switch.
Turn on into operational
loads.
Automatic restoration
after temperature
lowers (to 75° - 95° C)
Automatic restoration
after normal bias is
regained.
— 4 —
Page 6
Connection Examples
MAIN SPEAKER SYSTEM
SPEAKER SYSTEM
for foldback
From Speaker Jack
on Rear Panel
(Self powered speakers)
Low Z input should be connected
with low impedance (50 ohm ~ 600 ohm)
microphones
Line Out
Line Out
— 5 —
KEYBOARD
MUSICAL INSTRUMENT
CASSETTE TAPE DECK
for playback
Page 7
Input Connections
Generally speaking, there are two rules to follow when connecting equipment outputs
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 output 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
CH1
CH4
AUX
GEQ
PWR/AMP
INPUT
LOW Z
HIGH Z
ACTUAL
LOAD
IMPEDANCE
OPEN
27k
30k
50k
10k
FOR USE
WITH
NOMINAL
50
TO 250
MICROPHONES
27k
OR
LOWER IMP
LINES
30k
OR
LOWER IMP,
LINES
50k
OR
LOWER IMP,
LINES
10k
OR
LOWER IMP,
LINES
SENSITIVITY*
(PGM OUTPUT
LEVEL +4dB)
-60dB ( 0.78mV)
-35dB (13.8mV)
-20dB ( 77. 5mV )
+4dB (1.23V)
+4dB (1.23V)
CONNECTOR
XLR TYPE NC3F
PHONE JACK
RCA PIN JACK
PHONE JACK
PHONE JACK
PHONE JACK
*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 than 5m), we
recommend that balanced outputs be connected to balanced inputs.
As is described in the beginning of the Operating Instructions Manual, the connectors
of the MX-401 are wired as follows: Pin 1 is ground (shield). Pin 2 is cold (low, minus).
Pin 3 is hot (high, plus).
— 6 —
Page 8
Block and Level Diagrams
BLOCK DIAGRAMS
LEVEL DIAGRAM
— 7 —
Page 9
Specifications
MIXER SECTION
Frequency Response
+0, -3dB 60Hz~20kHz (input LEVEL at "5" position)
Total Harmonic Distortion
0.05% +4dB* a t 1kHz.
Hum and Noise (Open)
Equivalent Input Noise -130dB* (20Hz ~ 20kHz)
Equivalent Input Noise -133dB* (IHF A)
All
level
PGM Master at MAX and all
Controls
input level controls minimum -90dB* (IHF A)
PGM Master at MAX and one
input
level
CONNECTION
CH1
CH4
AUX
GEQ
PWR/AMP
Minim
control
um -110dB* (IHF A)
at MAX
-70dB*
INPUT
LOW Z
HIGH Z
ACTUAL
LOAD
IMPEDANCE
(IHF
OPEN
27k
30k
50k
10k
A)
Maximum Voltage Gain
INPUT to PGM out 64dB
INPUT to FB out 64dB
INPUT to GEQ out 64dB
AUX to PGM out 24dB
Input EQ
50Hz ±15dB Shelving
20kHz ±15dB Shelving
Equalization
63Hz ±12dB Peaking 2kHz ±12dB Peaking
250kHz ±12dB Peaking 8kHz ±12dB Peaking
1kHz ±12dB Peaking
INPUT SPECIFICATIONS
FOR USE
WITH
NOMINAL
TO 250
50
MICROPHONES
27k
OR
LOWER IMP
LINES
30k
OR
LOWER IMP,
LINES
50k
OR
LOWER IMP,.
LINES
10k
OR
LOWER IMP,
LINES
SENSITIVITY*
(PGM OUTPUT
LEVEL +4dB)
-60dB (0.78mV)
-35dB (13.8mV)
-20dB (77.5mV)
+4dB (1.23V)
+4dB (1.23V)
CONNECTOR
XLR TY PE NC3 F
PHONE JACK
RC A P IN J AC K
PHONE JACK
PHONE JACK
PHONE JACK
CONNECTION
PGM
GEQ
FB
ACTUAL
SOURCE
IMPEDANCE
600
600
600
POWER AMPLIFIER SECTION
Frequency Response
+0, -1dB 15Hz to 30k Hz
Rated Power & Load
150W
RMS (4
Power Output at Clipping
1%
THD,
1kHz
160W
RMS (4
Total Harmonic Distortion
Less th an 0.1% (200mW ~150W RMS, 20Hz~20kHz, 4
Typically below 0.05%
Compresser Dynamic Range
Greater than 26dB
Hum and Noise
At le ast 105dB S/N r at i o, 20Hz~20kHz
At least 109dB S/N ra tio I HF-A weighted
Damping Factor
Greater than 200 [1kHz 8
(150W
)
110W
RMS (8
) 115 W RMS (
RMS 4
)
)
)
OUTPUT SPECIFICATIONS
FOR USE WITH
NOMINAL
OR HIGHER
600!
IMP. LINES
OR HIGHER
600
IMP. LINES
OR HIGHER
600
IMP. LINES
)
OUTPUT LEVEL*
lbs)
MAX. BEFORE
CLIP
+20dB (7.75V)
+20dB (7.75V)
+20dB (7.75V)
NOMINAL
+4dB (1.23V)
+4dB (1.23V)
+4dB (1.23V)
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
*0dB is referenced to 0.775V RMS.
*Specifications are subject to change without notice.
CONNECTOR
PHONE JACK
PHONE JACK
PHONE JACK
Page 10
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 COMPRESSOR
POWER AMP T.H.D. vs POWER OUTPUT
REVERBERATION FREQUENCY RESPONSE
Appearance
304 (11.97")
— 9 —
494 (19.44")
(7.09")
180
Page 11
Toa Electric Co., Ltd.
KOBE, JAPAN
Printed in Japan
133-02-873-5
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