TOA Electronics A-912MK2 User Manual

Operating Instructions

TOA 900 SERIES II

MIXER POWER AMPLIFIER

A-903MK2 A-906MK2 A-912MK2

THE LIGHTNING FLASH WITH ARROWHEAD WITHIN A TRIANGLE IS INTENDED TO TELL THE USER THAT

PARTS INSIDE THE PRODUCT ARE A RISK OF ELECTRIC SHOCK TO PERSONS.

TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.

Please follow the instructions in this manual to obtain the optimum results from this unit.

We also recommend that you keep this manual handy for future reference.

THE EXCLAMATION POINT WITHIN A TRIANGLE IS INTENDED TO TELL THE USER THAT IMPORTANT OPERATING AND SERVICING INSTRUCTIONS ARE IN THE PAPERS WITH THE APPLIANCE.

TOA Corporation

Contents

General description

Features

Nomenclature

Front panel

Rear panel

Input connections

Output connections (A-903MK2)

Output connections (A-906MK2/A-912MK2)

Muting and remote volume control connection

Rack mounting

Operation

Volume adjustment

Tone control adjustment

Installation Servicing Specifications

Appearance (A-903MK2) Appearance (A-906MK2/A-912MK2)

3 3

6~7

7~8

9 9

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General Description

The TOA A-903MK2, A-906MK2 and A-912MK2 Mixer Power Amplifiers control and mix up to eight

independent input signals. The A-903MK2 delivers up to 30 watts of output power, the A-906MK2 60 watts

and A-912MK2 120 watts.

Optional plug-in modules are available for use with these mixer power amplifiers to provide versatility for a

wide range of operating applications. Edge connectors on the rear of the unit permit the selection of the TOA

plug-in modules.

The mixer power amplifiers have output terminals to match 4- or 8-ohm speaker systems, or speaker distribution systems may be connected to 25- or 70-volt terminals, and can be rack mounted by using optional rack mounting bracket MB-25B. The optional perforated panel PF-511 provides suitable ventilation,

finished in color to match the mixer power amplifiers.

Features

1. 8-channel mixer power amplifier

2. Wide frequency response : 20~20,000 Hz ± 1 dB

3. Low distortion and noise level

4. Remote master volume control

5. Excellent output regulation

6. Bass and treble controls

7. Bridging input/output

8. Self-protection circuitry design

9. Signal processing input/output

10. Varied output impedances : 4 ohms, 8 ohms, 25 and 70 volts

11. A full range of plug-in modules

12. Portable or rack mounting type

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Nomenclature

Front Panel

Power Switch

Applies line power. Two-position push button switch for on/off modes.

Power Indicator LED

Green LED lights when the power is switched "ON".

Signal Indicator LED

Green LED lights when more than –30 dB signal

level is fed to the inputs by means of the input

and master volume controls.

Normal Indicator LED

Yellow LED lights when fed to the proper signal

level.

Peak Indicator LED

Red LED lights when amplifier approaches clipping level. If steady lit, the input level control should be turned down until the LED flashes only intermittently.

Protection Indicator LED

Remains lit for about 5 seconds after power

switch is turned ON.

Input Volume Controls

Adjust gain of input #1 ~#8 respectively.

Bass Control

Modifies bass response. Turn clockwise to boost,

counter-clockwise to attenuate the bass

response. Tone is flat at center.

Treble Control

Modifies treble response. Turn clockwise to boost, counter-clockwise to attenuate the treble response. Tone is flat at center.

Tone Switch

Selects ON/OFF of the BASS and TREBLE controls. When slided to OFF, BASS and TREBLE controls are active. When slided to ON, they become inactive to make tone flat.

Low-Cut Switch

Cuts off unnecessary low frequency.

Master Volume Control

Adjusts overall gain of the unit.

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