TOA A-503-A, A-506-A, A-512-A Owners manual

Operation Instruction Manual

TOA 500 SERIES

MIXER POWER AMPLIFIER

Features

1. High quality design and construction.

2. Full frequency response: 50 - 15,000Hz, ±3dB.

3. Low distortion and noise level.

4. 4 microphone inputs, 3 auxiliary inputs and a mag. phono input.

5. Isolated-transformer outputs complete with 4 ohms, 25V

and

70V.

6. AC/DC operation: 120V AC and 24V DC

7. Individual bass and treble tone controls.

8. Signal processing input/output.

9. Self-protection circuitry design.

10. Muting function.

11. Remote volume control circuit.

A-503A A-506A A-512A

General Description

The TOA 500 series Mixer Power Amplifiers A-512A, A-506A and A-503A are designed for PA system applications such as paging, announcements, intercommunications, background music and broadcasting in industrial plants, offices, schools, churches, department stores, shopping centers, night clubs, dining rooms, convention halls, auditoriums and recreation areas. The Primary feature is their ability to withstand overload or short-circuits of output. Because of the TOA-engineered circuitry

design, the TOA 500 -series amplifiers require no complicated

protective circuit to withstand accidents and mismatched output connections that may occur during the installation or use of a PA system. This results in very high reliability. The 500 series amplifiers come with 4 microphone inputs, 3 auxiliary inputs and a mag. phono input. Input 1 (Mic 1) an d Input 2 (Mic 2) out of the 4 mic inputs are balanced inputs, while Input 3 (Mic 3) and Input 4 (Mic 4) are of unbalanced type. Input 3 and Input 4 can be changed to balanced type with the LI-51 microphone input module (optional). Two condenser microphone can be used with phantom power supplied from Input 1 and 2. And they have a remote volume control circuit on Input 2 as the volume can be adjusted at the microphone even when it is distant from the amplifier. The amplifiers are

muting function. They may be used in conjunction With a speaker rated at 4 ohms or with 25volt, 70volt constant-voltage speaker systems. Three auxiliary inputs and a mag. phono input are provided with RCA pin jack. Preamp-Out and Power-Amp-ln receptacles are provided for easy connection of a signal processor to the amplifier. Emergency operation can be made by DC power source (24V DC) even in case of AC power failure.

equipped

with

TOA Corporation

KOBE, JAPAN

133-02-767-7A

Printed in Taiwan

TOA 500 SERIES

Front Panel Controls and Features

No.

Power on-off switch

Power indicator

Input 1 - 5 volume controls

Bass control

Treble control

Master volume control

Block Diagram

Name

Function/Description

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

Comes on when power is turned on.

Adjusts gain of Input 1 -5 respectively.

Adjusts bass response. Turn clockwise (CW) to boost and counterclockwise (CCW) to attenuate the bass response. Tone is flat at center.

Adjusts treble response. Turn clockwise (CW) to boost and counterclockwise (CCW) to attenuate the treble response. Tone is flat at center.

Adjusts overall gain of unit.

A-503A, A-506A, A-512A

BLOCK DIAGRAM

No.

Name

AC power supply cord

AC outlet (unswitched)

AC fuse

24V DC terminals

Output terminals

Input 1 (Mic 1),

Input 2 (Mic 2) inputs

Pahntom power ON/OFF switch

(Mic

1, Mic 2)

Input 3 (Mic 3), Input 4 (Mic 4) inputs

Input 3 (Mic 3/Mag. phono) select switch

Input 4 (Mic 4/Aux 1) select switch

Mag. phono input

Aux 1 - 3 inputs

Aux 3 volume control

Tape output

Booster output

Preamp output

Power amp input

Link switch

Remote volume control terminals

Mute terminals

(adjustable muted level: 0 - 30dB)

Earth terminal

Function/Description

Connects to AC power supply.

Provides AC power for auxiliary equipment with power consumption of up to 500W.

Prevents excessive current flow.

Connect to DC power supply (24V).

Connect to speakers.

Connect to microphones of balanced 200 ohms with XLR connectors.

This switch is to be turned on when using the condenser microphone.

These screw terminal inputs connect to unbalanced 50k ohms

microphone.

Selects Mic 3 or Mag. phono input.

Selects Mic 4 or Aux 1 input.

Connects to the record player with MM type cartridge.

Connect aux inputs.

Adjusts gain of Aux 3.

Provides connections for a tape recorder. The input impedance of

the equipment should be more than 4.7k ohms.

Provides connections for a booster amplifier. The input impedance

of the equipment should be more than 600 ohms.

Connects to a signal processing equipment such as a limiter, equalizer etc. The input impedance of the equipment should be more than 600 ohms. In this case, Link switch should be set the "OUT" position.

When using this terminal, set Link switch to "OUT".

Disconnects between preamplifier and power amplifier when this switch is set to "OUT", allowing the connection of other equipment.

Mic 2 volume can be adjusted by means of a 10k-ohms potentiometer connected to these terminals.

Short-circuiting these terminals mutes input signals (inputs 3-5).

Normally connects to record player's ground.

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TOA 500 SERIES

(load) impedances.

A. Microphone

Installation

Do not block cover ventilation holes. The amplifier should not be placed in areas;

1) with poor ventilation.

2) exposed to direct sunlight.

3) With high ambient temperature or adjacent to

heat-generating equipment.

4) with high humidity or dust levels.

5) susceptible to vibration.

CAUTION

Do not remove the cover to prevents an electric shock.

Input Connections

A. Microphone

Four microphone inputs are provided. Two of them may be used with

balanced low impedance (30 - 600 ohms) microphone, or with

condenser microphone. The other may be used with an unbalanced high impedance (50k ohms) microphone. The microphone with the unbalanced connection cable of 30 - 70ft or balanced cable 70 - 230ft may be used depending on the microphone and its characteristic.

Mic 1 and Mic 2

1) for dynamic microphones — Low impedance (30 - 600 ohms) balanced microphone inputs are provided with a XLR connector.

2) for condenser microphones - Condenser microphones can be used with supplying DC 15V phantom power, while turning on the phantom power switch above the mic input connector.

Mic 3 and Mic 4 — High impedance (50k ohms) unbalanced type microphone inputs are provided with screw terminals. Using Mic 3 input, the Input 3 select switch must be turned to Mic 3. Using Mic 4 input, the Input 4 select switch must be turned to Mic 4.

B. Record player

Record player with MM (moving magnet type) cartridge may be connected to Mag. Phono input (2mV, 50k ohms). Use single or double conductor shielded cable with a terminating

RCA pin plug. It is recommended that a separate ground wire be connected between the record player base and the earth ( ) screw terminal on the rear panel.

Output Connections

Speaker output

The speaker outputs of the amplifier are 4 ohms, 25V, and 70V. Connect the speakers cable to one of these outputs, after removing the screw terminal cover. Put the cover back on when finished the connection.

Class 2 wiring may be used. Since these outputs consist of 4 ohms, 25V and 70V via the output transformer (matching transformer) the connecting method differs in

each case. See the following diagrams.

Note: Impedances indicated below imply total speaker system

(load) impedances.

<A-503A>

Output Terminal

<A-506A>

Output Terminal

<A-512A>

Output Terminal

C. Radio tuner, cassette tape player and other BGM sources A radio tuner, tape player, chime, mixer preamplifier, compact disk

player or other high level signal sources may be connected to the

AUX-1, AUX-2 or AUX-3 input.

Use single or double conductor shielded cable with a terminating

RCA pin plug.

CAUTION

When connecting speakers to any one of the outputs of 4

ohms, 25V or 70V.

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