M-243
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 +4 dB (maximum +20 dB), unbalanced (phone) at less than 0.01%. Recording output
shall be nominal -4 dB (maximum +6 dB), unbalanced (RCA pin) at less than 0.01%. Inputs: CH
1, CH 2 mono XLR, balanced mic input shall be nominal -60 dB (maximum -30 dB) 1k ohm input
impedance; XLR balanced mic (pad) input shall be nominal -40 dB (maximum -10 dB) 1k ohm
input impedance; and unbalanced phone line input shall be nominal -10 dB 10k ohms input
impedance. CH 3 to CH 6 (L/R stereo input) shall be nominal -10 dB 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 +4 dB (maximum +20 dB) 50k ohms input
impedance. A-weighted noise levels shall be at least -105 dB below rated nominal output for
Stereo Out (L, R) and –98 dB below rated nominal output for Mono Out (1, 2) (all level controls
minimum) and at least -94 dB below rated nominal output for Stereo Out (L, R), and -95 dB below
rated nominal output for Mono Out (1, 2) (stereo, mono (1, 2) max.). Frequency response shall be
+1/-2 dB from 20 to 20k Hz 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 -20 dB 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 +/-15 dB at
20 Hz and a high frequency shelving equalizer of +/-15 dB at 20k Hz. 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 shall be 10 W. The mixer shall be enclosed in a durable,
black enclosure. Dimensions (W x H x D) shall be 19.0" x 1.7" x 11.9" (483.0 x 44.0 x 301.8 mm).
Weight shall be 8.4 lbs. (3.8 kg).

The mixer shall be TOA model M-243.