Toa M-243 User manual

TOA PROFESSIONAL SOUND SYSTEM
STEREO MIXER
M-243
DESCRIPTION
The TOA M-243 is a highly flexible rack mount mixer with
two monaural and four stereo inputs, plus one stereo and
two mono outputs. There are also mix bus sub-inputsand
a stereo record output. It is designed especially for
commercial systems that require mixing and matrixing a
combination of mono and stereo audio sources to one or
several outputs, and in which stereo sources may have to
be summed to mono and monaural sources sent to L/R
outputs.
The compact, single rack space M-243 can be easily
configured to serve as anything from a single mono or
stereo mixer to a mixer with six regular inputs and three
outputs. Each output also has its own separate sub-input.
The M-243 is ideal for a variety of systems, including
boardrooms, conference rooms, health clubs, restaurants
and background music (BGM) applications. For example,
in a restaurant, the M-243 can simultaneously and
separately control stereo classical music in the dining room,
stereo easy listening music in the bar and foyer, plus BGM
and paging of customers when their tables are ready.
The M-243 has two monaural line inputs (#1 and 2) that are
switchable between balanced XLR microphone level or
unbalanced 1/4" phone line level, and four unbalanced L/R
stereo inputs (#3~6) with RCA-type jacks. Input 6 has both
RCA type and 1/4" phone jacks connected in parallel. Each
of the inputs has its own volume control and a set of three
assignment switches for assigning the input to any
combination of the three outputs. The two monaural inputs
each have an automatic compressor to prevent excessive
input signals from clipping the mixer output. Each also has
a high pass filter to filter out unwanted low frequencies,
particularly for speech use, and a -20dB pad in the mic
input circuitry to accommodate high output or close-talked
microphones. Filter and pad on/off switches are internal to
prevent any tampering.
The M-243 has other line level inputs: a L/R stereo sub-input
and mono sub-inputs 1 and 2. These directly feed the
mixing buses and their associated outputs. The stereo
sub-input is configured so that by connecting a monaural
signal to the left channel, it will be fed to both the left and
right output channels. Among other applications, one of the
monaural outputs could be fed into the stereo sub-input as
a sub-group mix for the stereo output.
A unique feature of the M-243 is an automatic muting
function (switchable on/off). This detects signal on either of
the monaural inputs and mutes any of the stereo input
signals assigned to the L/R stereo output. This is very
useful for priority paging that auto-mutes BGM or for
automatic program selection. For example, in a sports
lounge, the TV audio could automatically mute the BGM
whenever the TV is turned on. Meanwhile, because the
stereo input assignments to the mono outputs are
unaffected, the same BGM signal could still go
uninterrupted to the associated restaurant system that is
being fed from one of the mono outputs.
Three sets of output mixing buses are provided to feed the
three sets of main outputs: L/R Stereo, Mono 1 and Mono 2.
Each output has a separate volume control on the front
panel. The L/R Stereo output also has bass and treble
shelving-type tone controls. Each of the mono outputs has
an internal switch that allows it to function as a sum of the
stereo output. There is also a L/R stereo recording output
from the L/R stereo mix bus prior to the output EQ and
volume.
Other features include provision of colored control knobs for
the different control functions; a clipping indicator that lights
when any signal in the output section reaches 3dB below
clipping; an internal ground lift switch that separates the
audio and chassis grounds to avoid ground loops; an
included security cover for the assignment switches and a
power switch with a power-on indicator. The M-243
occupies only one standard 19" EIA rack and includes
removable rack mounting ears.

FEATURES SPECIFICATIONS
1. Two monaural and four stereo inputs; one stereo and
two mono outputs plus a stereo and two mono sub-
inputs to the output mix buses.
2. Each input can be assigned to any combination of the
three outputs.
Model No. M-243
Frequency Response 20Hz to 20kHz (+ 1.0, -2.0dB)
Total Harmonic Distortion Less than 0.01% (1kHz. rated input/output)
3. Monaural inputs switchable between microphone and
line level signals with a -20dB pad in the mic input
circuitry for high output or close-talked microphones.
4. Switchable high pass filter on each monaural input to
filter out unwanted low frequencies, especially for
speech use.
Noise Level (A-Weighted)
ALL MIN.
STEREO OUT (L, R): -105dB or less
MONO OUT (1, 2): -98dB or less
STEREO, MONO, STEREO OUT (L, R): -94dB or less
1, 2 MAX.
MONO OUT (1, 2): -95dB or less
Power Requirements AC mains
Power Consumption 10 watts (120V version); 12 watts (220-240V version)
Dimensions (W x H x D)
483.0 x 44.0 x 301.8mm (19.0 x 1.7 x 11.9 in.)
Weight
3.8kg (8.4lbs.)
5. A compressor for each monaural input to prevent
excessive input signals from clipping the mixer output.
6. Automatic muting circuit (switchable on/off) mutes
stereo signals assigned to the stereo output by
detecting signals on the monaural inputs.
7. Stereo output has a separate L/R recording output and
bass/treble type equalization.
8. Ground lift switch to break ground loops that can
generate noise.
Finish Black
* 0dB is referenced to 0.775V RMS
INPUTS AND OUTPUTS
Nomenclature
(MONO INPUT) MIC
-60dB -3OdB
1k Ω
1: GND, 2 GOLD,
3: HOT
9. Front panel knobs supplied in different colors for easy
association with their function.
10. Security cover for the input assignment switches also
serves as a write-in strip for input identification.
LINE
(ELECTRICAL BAL)
MIC (PAD) -40dB -10dB
-10qdB - 10k
Ω
PHONE (UNBAL)
CH3~CH6
(STEREO INPUT L. R) -10dB -
1Ok Ω
RCA PIN (UNBAL)
(CH 6... & PHONE)
SUB INPUT
STEREO (L/M,R) +4dB +20dB 50k
Ω
PHONE (UNBAL)
MONO (1,2) +4dB +20dB 50k
Ω
PHONE (UNBAL)
STEREO OUTPUT (L, R)
MONO OUTPUT (1, 2)
Impedance
level level
Connector
type
CH1, CH2 XLR TYPE
Maximum
Rated
+4dB
+4dB
+20dB
+20dB
1k Ω
1k Ω
PHONE (UNBAL)
PHONE (UNBAL)
REC OUTPUT (L,R) -10dB +6dB 1k
Ω RCA PIN (UNBAL)
* 0dB=0.775V rms
BLOCK DIAGRAM AND LEVEL DIAGRAM

APPEARANCE AND DIMENSIONAL DIAGRAM
Unit: mm (in.)
ARCHITECTS AND ENGINEERS
SPECIFICATIONS
The mixer shall have two selectable monaural mic/line
inputs and four stereo line inputs; one stereo output and two
monaural outputs. The mixer shall have four mixing buses:
L/R stereo, and 1, 2 monaural. It shall incorporate all solid
state circuitry. Stereo and mono power outputs shall be
nominal +4dB (maximum +20dB), unbalanced (phone) at
less than 0.01%. Recording power output shall be nominal
-4dB (maximum +6dB), unbalanced (RCA pin) at less than
0.01%.
Inputs: CH 1, CH 2 mono XLR, balanced mic input shall be
nominal -60dB (maximum -30dB) 1k ohm input
impedance; XLR balanced mic (pad) input shall be nominal
-40dB (maximum -10dB) 1k ohm input impedance; and
unbalanced phone line input shall be nominal -10dB 10k
ohms input impedance. CH 3 to CH 6 (L/R stereo input)
shall be nominal -10dB 10k ohms input impedance
(unbalanced RCA pin + CH 6 parallel phone connection).
Stereo (L/M, R) and mono (1, 2) sub-inputs (unbalanced,
phone) shall be nominal +4dB (maximum +20dB) 50k
ohms input impedance. A-weighted noise levels shall be at
least -105dB below rated nominal output for Stereo Out
(L, R) and -98dB below rated nominal output for Mono Out
(1, 2) (all level controls minimum) and at least -94dB below
rated nominal output for Stereo Out (L, R), and -95dB below
rated nominal output for Mono Out (1, 2) (stereo, mono
(1, 2) max.). Frequency response shall be +1/-2dB from
20Hz to 20kHz at any power up to rated output.
Each of the two monaural inputs shall have both
microphone and line level input jacks with line priority if both
are connected; a compressor circuit to protect the mixer
from being driven into output clipping from excessive input
levels, a switchable high pass filter (HPF), and a -20dB pad
(PAD) in the microphone circuitry. The filter and pad
switches shall be internal to prevent tampering.
A sub-input shall be provided for each mixing bus for the
stereo and two mono outputs. A switchable On/Off muting
function shall automatically mute the stereo signals
assigned to the L/R stereo mix bus upon detection of a
useable signal in either monaural input channel. Each
mono output shall have an internal switch to change its
function to being a mono sum of the L/R stereo output. The
stereo output shall be provided with a low frequency
shelving equalizer of +/-15dB at 20Hz and a high
frequency shelving equalizer of +/-15dB at 20kHz.
The front panel shall have: a power On/Off switch, six input
level controls; six sets of L/R three-input assignment
switches (L/R Stereo, Mono 1, Mono 2) with security cover;
auto-mute On/Off; low and high frequency equalizer
controls; three output level controls for L/R Stereo, Mono 1
and Mono 2; a power On/Off switch and power indicator.
The rear panel shall have: 1/4" and XLR jacks for inputs 1-2
(monaural), four pairs of RCA-type jacks for inputs 3-6
(stereo), plus two 1/4" L/R jacks for input 6; four pairs of
RCA-type jacks for the sub-inputs and record outputs; four
1/4" phone jacks for the L/R Stereo, Mono 1 and Mono 2
outputs; AC power input. The stereo sub-input jack shall
feed signal to left and right stereo outputs when only the L
input is connected.
An internal ground lift (GND) shall disconnect the audio
ground from the chassis in the LIFT position. Power shall
be by AC line mains. Power consumption for the 120V
version shall be 10W (12W 220/240V). The mixer shall be
enclosed in a durable, black enclosure. Overall dimensions
shall be 483.0(W) x 44.0(H) x 301.8(D)mm (19.0" x 1.7" x
11.9"). Weight shall be 3.8kg (8.4lbs.). Standard EIA
equipment rack mounting, operating instructions, 2 small
blue and 2 small red knobs, and 1 large blue and 1 large
red knobs shall be provided. The mixer shall be the TOA
model M-243.
NOTE; 0dB=0.775V RMS

TOA Corporation
* Specifications are subject to change without notice
Printed in Japan (407) 833-64-113-50