Toa A-503A Operating Instructions 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.
TOA Corporation
KOBE, JAPAN
Operation Instruction Manual

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) and 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 mic-
rophone 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 equipped with
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.
A-503A
A-506A
A-512A
133-02-767-7A
Printed in Taiwan