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P912A, P906A NEW 900 SERIES POWER AMPLIFIER Operation Instruction Manual
TOA NEW 900 SERIES
POWER AMPLIFIER
P912A
2 Low
distortion
and
noise level
3 Excellent output regulation
4 A full range of plug-in modules
5 Self-protecting
circuitry
design
6 Varied
output impedances; 4 and 8 ohms, 25 and 70 volts
7
Input
level switch (selectable 1,000mV/100mV)
8 Portable
or
rack-mounting
type
The TOA P-906A and P-912A Power Amplifiers deliver up to 60
watts and 120 watts of power respectively at less than 0.5% total
harmonic distortion (THD) from 20 to 20,000 Hz (transformerless
4-ohm output). The P-906A and P-912A have a high-impedance
direct input and an input port (edge connector) to accept one
module accessory. Module selection is determined by application
among the TOA plug-in modules:
The H-01 s e r i e s , H-02 s e r i e s and H-03 series Microphone Pre-
amplifiers, E-01 Mag. Phono Preamplifier, the X-01 series Auxiliary
Preamplifiers for high-level sources, the B-01 series Bridging Trans-
formers for bridging high-impedance lines, the L-01 series Line
Matching Transformers for matching 600-ohm lines, 1-01 Paging
Input for combining with the TOA Intercom System EXES-1000,
EXES-5000 and EX-16, and the S-01, S-02 and S-03 Tone signal
generators for generating attention-getting signals and 1 kHz sine
wave for testing within the total system.
The P-906A and P-912A have a low-cut switch for a cutoff frequency
of 60 Hz, and an input-level switch for input sensitivity of 1V
(0dBv) or 100mV (20dBv). Output terminals provide connections
for 4-ohm and 8-ohm speakers, plus 25-volt and 70-volt speaker dis-
tribution outlets.
With plug-in modules, the TOA P-906A and P-912A Power Am-
plifiers may be used as a pre/power amplifier.
The P-906A and P-912A can be rack mounted by using the MB-931
Rack-mounting Bracket accessory. The PF-911 Perforated Panel
(1.73 inches, 1 rack unit) accessory provides suitable ventilation,
finished in color to match the P-906A and P-912A.
1 3 3 - 0 2 - 7 4 0 - 6
Printed in Japan
Toa Electric Co., Ltd.
KOBE, JAPAN
Features
General Descriptions
P906A
1 Wide
frequency
response; 20 20,000 Hz, �1dB Item
1
2
3
Name
POWER
ON-OFF
SWITCH
METER
INPUT
VOLUME
CONTROL
Function/Description
Applies line power. Two-position
pushbutton switch for on-off modes.
Indicates the output level of the
amplifier. At rated output, it shows
0 VU (at continuous sine-wave
signal input).
When power is turned on, meter
illuminates.
Adjusts gain of INPUT.
1
Item
1
2
3
4
5
6
7
8
9
10
Nam e
AC POWER
SUPPLY
CORD
AC OUTLET
(Unswitched)
AC FUSE
OUTPUT
FUSE
OUTPUT
TERMINALS
MODULE
INPUT
PORT
LOW-CUT
SWITCH
INPUT-
LEVEL
SWITCH
DIRECT
INPUT
TERMINAL
EARTH
TERMINAL
Function/Description
Connects to power source.
Provides AC power for auxiliary equipment
with power consumption of up to 500W.
Protects amplifier from excessive current
drain. Replace only with same type fuse.
Refer to qualified service personnel if fuse
blows repeatedly.
Connect to speakers.
Accepts PLUG-IN MODULES which are
optionally available. Module selection is
determined by application.
Cuts off unnecessary low frequency.
Selects input sensitivity. Place in "1V
(0dBv)" position when normally used
Note: The position of INPUT-LEVEL
SWITCH should be changed according to
modules used or equipment connected to
Connects directly to external equipment
without using modules. Unbalanced
10k ohms.
Normally connects to a record player's
ground.
AC FUSE
OUTPUT FUSE
P-906A
P-912A
250V 5A
250V 3A
250V 6A
250V 10A
Front Panel Controls and Features Rear
Panel Controls and Features
as a power
amplifier.
DIRECT INPUT TERMINAL. Plug-in Modules and Input Level SW Setting
Plug-in Modules
Balanced low impedance microphone preamp. module
(with presettable low-cut filter, high-cut filter and
gain controls)
Balanced low impedance microphone preamp. module
(with pressetable low-cut filter, high-cut filter
and gain controls, and remote control facilities)
Balanced low impedance microphone preamp. module
(with presettable low-cut filter and gain controls)
Balanced low impedance microphone preamp. module
(with presettable low-cut filter and gain controls,
and remote control facilities)
Unbalanced high impedance microphone preamp. module
(with presettable low-cut filter and gain controls)
Equalized mag. phono preamp. module
(with presettable gain control)
Unbalanced high impedance auxiliary preamp. module
(with presettable gain control)
Unbalanced high impedance auxiliary preamp. module
(with presettable gain control and remote control
facilities)
bridging transformer module
Balanced 600 line matching transformer module
Balanced paging input module
(with presettable gain control)
Signal tone generator module
(with presettable output level control)
1 kHz sine wave
Yelp and buzzer
One-tone chime and continuous one-tone chime
Model
No,
H-01
H-21
H-02
H-22
H-03
E-01
X-01
X-21
B-01
L-01
l-01
S-01
S-02
S-03
Input Level SW Setting
1V
(0dBv)
-
_
-
-
-
-
-
-
0
o
-
-
100mV
0
0
0
o
0
o
0
o
0
o
0
0
See PLUG-IN MODULES for details. Two types of input terminals are provided on the rear for input
connections.
( 1 ) 2P terminal (marked HOT, E)
It is provided for direct input (unbalanced, 10k ohms) without
using plug-in module. This terminal is directly connected with
a potentiometer inside.
(2) Plug-in module input
Select the desired module according to application. Plug the module into INPUT PORT, sliding it between the guide
rails, and secure with two screws. When INPUT PORT is not occupied, cover the PORT with the
blank panel, and secure it with screws. Be sure that INPUT-LEVEL SWITCH is in the proper position
for the module used or the equipment connected to DIRECT
INPUT TERMINAL. When the P-906A or P-912A is used in combination with a mixer
preamplifier or serves as an incremental power amplifier, normally
Input Connections
place INPUT LEVEL SWITCH in "1V ( 0 dBv)" position,
(20dBv)
Balanced 10k
2 Note:
When the temperature of heat sink exceeds 105�C, the protection
circuit is activated and the output is disconnected from the
circuit. The signal automatically begins to be output as the
temperature goes down. In such a case, confirm whether or not
unit is overloaded or operated on an excessive output. 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 dusty levels.
5. susceptible to vibration.
The speaker outputs of the amplifier are 4
, 8
, 25V and 70V.
Connect speakers to one of these outputs.
Class 2 wiring may be used.
Since these outputs consist of 8
, 25V and 70V via the output
transformer (matching transformer) and direct output of 4
, the
connecting method differs in each case. See the following diagrams.
Note: Impedances indicated below imply total speaker system
(load) impedance. When connecting speakers to any one of the outputs of 8 O, 25V
or 70V (BALANCED TRANSFORMER OUTPUT);
Note:
In this case, the LOW-CUT SWITCH should be in "CUT" posi-
tion. This amplifier is characteristically flat even in the low fre-
quency range. Therefore, in TRANS OUTPUT, the acoustic
effect and frequency-response characteristics may be altered.
In TRANS OUTPUT, cut off unnecessary low frequency to ob-
tain the best acoustic condition.
SWITCH in "CUT" position

When connecting speakers to the 4 output. (UNBALANCED
DIRECT OUTPUT);
Installation
Output Connections P-906A, P-912A
Place the LOWCUT
3 When all connections are completed, turn power switch on. Then,
the meter is illuminated. Approx. 5 seconds after switching power
on, the amplifier comes into operation.
ADJUSTMENT OF VOLUME CONTROL
Adjust the input volume control to obtain appropriate output level.
In normal use of BGM playing or announcement, the deflection of
the meter is recommended to be within the range as indicated in the
drawing. Tone quality will be considerably deteriorated if the
pointer indicates around 0 VU.
To mount the amplifier in a standard 19-inch equipment rack, use
the MB-931 Rack-mounting Bracket accessory.
In normal use of BGM
playing or announcement.
The pointer of meter indicates 0 VU if continuous signals like sine
waves are applied to the input of the amplifier.
Remove 4 screws securing case.
Fix the MB-931 with attached 4 screws.
MB-931 The
length
of
the
screws
should not
(Silver)
exceed 12mm (1/2 inches).
( O P T I O N )
Perforated Panel
PF-911 (OPTION)
(Silver)
If two or more amplifiers are mounted in
an equipment rack, space should be pro-
vided between the units for ventilation.
The PF-911 Perforated Panel is recom-
mended for this purpose.
Continuous signals
When the power amplifier is use