TOA M-243 Stereo Mixer Instruction Manual

: August 8, 2024
: TOA

Table of Contents

TOA M-243 Stereo Mixer
IMPORTANT SAFETY INSTRUCTIONS
SAFETY PRECAUTIONS
GENERAL DESCRIPTION
FEATURES
NOMENCLATURE AND FUNCTIONS
INTERNAL SWITCH SETTINGS
BLOCK AND LEVEL DIAGRAMS
DIMENSIONAL DIAGRAM
SPECIFICATIONS
Accessories
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TOA M-243 Stereo Mixer

TOA-M-243-Stereo-Mixer-product

IMPORTANT SAFETY INSTRUCTIONS

Read these instructions.
Keep these instructions.
Heed all warnings.
Follow all instructions.
Do not use this apparatus near water.
Clean only with a dry cloth.
Do not block any ventilation openings. Install in accordance with the manufacturer’s instructions.
Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.
Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades one wider than the other. A grounding-type plug has two blades and a third grounding prong. The wide blade or the third prong is provided for your safety. If the provided plug does not fit into your outlet, consult an electrician for the replacement of the obsolete outlet.
Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.
Only use attachments/accessories specified by the manufacturer.
Use only with the cart, stand, tripod, bracket, or table specified by the manufacturer, or sold with the apparatus. When a cart is used, use caution when moving the cart/apparatus combination to avoid injury from tip-over.
Unplug this apparatus during lightning storms or when unused for long periods of time.
Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.

SAFETY PRECAUTIONS

Before installation or use, be sure to carefully read all the instructions in this section for correct and safe operation.
Be sure to follow all the precautionary instructions in this section, which contain important warnings and/or cautions regarding safety.
After reading, keep this manual handy for future reference.

Safety Symbol and Message Conventions
Safety symbols and messages described below are used in this manual to prevent bodily injury and property damage that could result from mishandling. Before operating your product, read this manual first and understand the safety symbols and messages so you are thoroughly aware of the potential safety hazards.

WARNING indicates a potentially hazardous situation that, if mishandled, could result in death or serious personal injury.
CAUTION indicates a potentially hazardous situation which, if mishandled, could result in moderate or minor personal injury, and/or property damage.

WARNING

When Installing the Unit

Do not expose the unit to rain or an environment where it may be splashed by water or other liquids, as doing so may result in fire or electric shock.
Ne pas exposer l’appareil à la pluie et le protéger de tout contact avec de l’eau ou d’autres liquides afin d’éviter un incendie ou une électrocution.
Use the unit only with the voltage specified on the unit. Using a voltage higher than that which is specified may result in fire or electric shock.
Do not cut, kink, or otherwise damage nor modify the power supply cord. In addition, avoid using the power cord in close proximity to heaters, and never place heavy objects — including the unit itself — on the power cord, as doing so may result in fire or electric shock.
Since the unit is designed for indoor use, do not install it outdoors. When it gets wet with rain, there is a danger of electric shock.
The apparatus shall be connected to a main socket outlet with a protective earthing connection.
The socket outlet shall be installed near the equipment and the plug shall be easily accessible.

When the Unit is in Use

Should the following irregularity be found during use, immediately switch off the power, disconnect the power supply plug from the AC outlet and contact your nearest TOA dealer. Make no further attempt to operate the unit in this condition as this may cause fire or electric shock.
If you detect smoke or a strange smell coming from the unit.
If water or any metallic object gets into the unit
If the unit falls, or the unit case breaks
If the power supply cord is damaged (exposure of the core, disconnection, etc.)
If it is malfunctioning (no tone sounds.)
To prevent a fire or electric shock, never open nor remove the unit case as there are high-voltage components inside the unit. Refer all servicing to qualified service personnel.
Do not place cups, bowls, or other containers of liquid or metallic objects on top of the unit. If they accidentally spill into the unit, this may cause a fire or electric shock.
Do not insert nor drop metallic objects or flammable materials in the ventilation slots of the unit’s cover, as this may result in fire or electric shock

CAUTION

When Installing the Unit

Never plug in nor remove the power supply plug with wet hands, as doing so may cause electric shock.
When unplugging the power supply cord, be sure to grasp the power supply plug; never pull on the cord itself. Operating the unit with a damaged power supply cord may cause a fire or electric shock.
When moving the unit, be sure to remove its power supply cord from the wall outlet. Moving the unit with the power cord connected to the outlet may cause damage to the power cord, resulting in fire or electric shock. When removing the power cord, be sure to hold its plug to pull.
Avoid installing the unit in humid or dusty locations, in locations exposed to direct sunlight, near the heaters, or in locations generating sooty smoke or steam as doing otherwise may result in fire or electric shock.
Be sure to follow the instructions below when rack-mounting the unit. Failure to do so may cause a fire or personal injury. · Install the equipment rack on a stable, hard floor. Fix it with anchor bolts or make other arrangements to prevent it from falling down.
When connecting the unit’s power cord to an AC outlet, use the AC outlet with the current capacity allowable to the unit.
The supplied rack-mounting screws can be used for the TOA equipment rack only. Do not use them for other racks.

When the Unit is in Use

If dust accumulates on the power supply plug or in the wall AC outlet, a fire may result. Clean it periodically. In addition, insert the plug in the wall outlet securely.
Switch off the power, and unplug the power supply plug from the AC outlet for safety purposes when cleaning or leaving the unit unused for 10 days or more. Doing otherwise may cause a fire or electric shock.

The lightning flash with the arrowhead symbol, within an equilateral triangle, is intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operation and maintenance (servicing) instructions in the literature accompanying the appliance.

GENERAL DESCRIPTION

The M-243 is a stereo mixer equipped with 2 monaural inputs, 4 stereo inputs, 1 stereo output, and 2 monaural outputs. It can be mounted in an EIA component rack (1U size). 1U size = 44.5 mm or 1.75″ (standard size)

FEATURES

2 monaural inputs, 4 stereo inputs, 1 stereo output, and 2 monaural outputs. Assign each input signal to 3 output channels individually.
Sub-input terminals for stereo output channel and each of 2 monaural output channels.
Microphone input or line input for monaural input selectable depending on the signal level. Built-in limiter circuitry eliminates distortion under excessive input levels. High-pass filter as well as PAD (only for MIC input) in the monaural line available by the internal switch settings.
Peak indicator to detect clipping.
n “Automatic Muting” circuit automatically mutes the stereo output signal by detecting the monaural input signal. (ON/OFF switchable)
A recording output and equalizer (high and low frequencies) for the stereo output channel.
2 channel monaural outputs are usable as sum outputs for the stereo output channel individually by the internal switch setting.
Protective cover for protecting the setting position of each input usable as a writing plate.
Knobs supplied in different colors and sizes are easily replaceable depending on the intended use, improving the operability of the unit.

NOMENCLATURE AND FUNCTIONS

[Front]

Power switch
Power is switched on and off with each depression of this switch.
Power indicator
Lights when the power switch is set to ON.
Assignment keys [ST, 1, 2] elect one of the following output destinations to which the post-fader input signals are routed. Signals are output when pressed. ST: Stereo output
MONO 1 output
MONO 2 output
Protective cover
Used to protect the setting position of the assignment keys (3) from accidental operation. It can be used as a writing plate.
Peak indicator
Lights when the output signal reaches 3 dB below clipping. Be sure to adjust each input level so that the Peak indicator does not light continuously
Equalizer controls [EQ: LOW & HIGH]
Adjust stereo output signal tone.
LOW: Low-frequency adjustment (20 Hz, ±15 dB shelving)
HIGH: High-frequency adjustment (20 kHz, ±15 dB shelving)
Stereo output level control
Adjusts the stereo output level.
Input level controls [1 – 6]
(1 – 2: Monaural input, 3 – 6: Stereo input) Adjust the input level of each channel.
Mute key
Activates muting when pressed. (Indicator lights.) [Muting function] This function works only for the stereo output channels. Attenuates the signals applied to Channels 3 through 6 by detecting signals applied to Channel 1 or
(This function does not work for the monaural output signal.)
Monaural output level controls
Adjust the monaural output level.
[Rear]
AC inlet
Connect the supplied power cord.
Functional earth terminal
Hum noise may be generated when external equipment is connected to the unit. Connecting this terminal to the functional earth terminal of the external equipment may reduce the hum noise.
Not e: This terminal is not for protective earth.
Monaural output jacks
Function as sum output for the stereo output channel by the internal switch setting. (Refer to section “6. INTERNAL SWITCH SETTINGS.”)
Stereo output jacks
Recording output jacks Output the signal from the stereo output bus for recording

INTERNAL SWITCH SETTINGS

WARNING

This work should only be performed by a qualified professional electrician. If users open the unit case or modify the unit, this may cause fire or electric shock.

The functions below can be made available by changing the switch settings inside the unit.

“PAD” switch: Set to the “IN” position to insert PAD (20 dB) in the monaural input (microphone input).
“HPF” switch: Set to the “IN” position to insert a High pass filter (300 Hz, –6 dB/Oct) in the monaural input.
“GND” switch: When the unit is connected to external equipment, a ground may create a loop, potentially generating a noise (hum). In such cases, set this switch to the LIFT position to cut off the ground loop.
“MONO1” and “MONO2” switch: Set to the “ST SUM” position to change each monaural output to stereo sum output for the stereo output channel.

TOA-M-243-Stereo-Mixer-fig-6

BLOCK AND LEVEL DIAGRAMS

TOA-M-243-Stereo-Mixer-fig-7

DIMENSIONAL DIAGRAM

TOA-M-243-Stereo-Mixer-fig-8

SPECIFICATIONS

Power Source| M-243 L: 120 V AC, 60 Hz

M-243 301H: 220 – 240 V AC, 50/60 Hz

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Power Consumption| M-243 L: 10 W M-243 301H: 12 W
Monaural Input| Line: –10 dB, 10 kΩ, unbalanced, φ 6.3 mm phone jack (2 P) Mic: –60 dB, 1 kΩ, balanced, 3-pin XLR connector

Mic (Pad): –40 dB*, 1 kΩ, balanced, 3-pin XLR connector

Stereo Input (L, R)| –10 dB, 10 kΩ, unbalanced, RCA jack
Auxiliary Monaural Input| +4 dB, 50 kΩ, unbalanced, φ 6.3 mm phone jack (2 P)
Auxiliary Stereo Input| +4 dB, 50 kΩ, unbalanced, φ 6.3 mm phone jack (2 P)
Stereo Output (L, R)| +4 dB, 1 kΩ, unbalanced, φ 6.3 mm phone jack (2 P)
Monaural Output| +4 dB, 1 kΩ, unbalanced, φ 6.3 mm phone jack (2 P)
REC Output (L, R)| –10 dB, 1 kΩ, unbalanced, RCA jack
Frequency Response| 20 Hz – 20 kHz (+1, –2 dB)
T.H.D.| 0.01 % or less (1 kHz, rated input/output)
Noise Level (IHF-A)| When all volume controls are in minimum position.

Stereo output (L, R): –105 dB or less Monaural Output (1, 2): –98 dB or less

When the stereo, monaural (1, 2) are in maximum position Stereo output (L, R): –94 dB* or less

Monaural Output (1, 2): –95 dB* or less

Finish| Front Panel: Alumite, black Case: Steel, black
Dimensions| 483 (w) x 46 (h) x 301.8 (d) mm (19.02″ x 1.81″ x 11.88″)
Weight| 3.8 kg (8.38 lb)

0 dB = 0.775 Vrms
Note: The design and specifications are subject to change without notice for improvement.