Operation Instruction Manual
TOA NEW 900 SERIES
P906A
P912A
POWER AMPLIFIER
General Descriptions
Features
1
2
3
4
5
6
7
8
Wide frequency response; 20 — 20,000 Hz, ±1dB
Low distortion and noise level
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:
Excellent output regulation
A full range of plug-in modules
Self-protecting circuitry design
Varied output impedances; 4 and 8 ohms, 25 and 70 volts
Input level switch (selectable 1,000mV/100mV)
Portable or rack-mounting type
The H-01 series, H-02 series 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
wave for testing within the total system.
1
kHz sine
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.
133-02-740-6
Printed in Japan
ToaElectricCo.,Ltd.
KOBE, JAPAN
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Front Panel Controls and Features
Rear Panel Controls and Features
Item
Function/Description
Name
Item
Nam e
Function/Description
Connects to power source.
POWER
ON-OFF
SWITCH
1
Applies line power. Two-position
pushbutton switch for on-off modes.
1
AC POWER
SUPPLY
CORD
METER
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.
Provides AC power for auxiliary equipment
with power consumption of up to 500W.
2
3
AC OUTLET
(Unswitched)
2
AC FUSE
Protectsamplifier from excessive current
drain. Replace only with same type fuse.
Refer to qualified service personnel if fuse
blowsrepeatedly.
3
4
OUTPUT
FUSE
Adjusts gain of INPUT.
INPUT
VOLUME
CONTROL
P-906A
250V 3A 250V 5A
P-912A
AC FUSE
OUTPUT FUSE 250V 6A 250V 10A
Connect to speakers.
5
6
OUTPUT
TERMINALS
MODULE
INPUT
PORT
Accepts PLUG-IN MODULES which are
optionally available. Module selection is
determined by application.
LOW-CUT
SWITCH
Cuts off unnecessary low frequency.
7
INPUT-
LEVEL
SWITCH
Selects input sensitivity. Place in "1V
(0dBv)" position when normally used
as a power amplifier.
Note: The position of INPUT-LEVEL
SWITCH should be changed according to
modules used or equipment connected to
DIRECT INPUT TERMINAL.
8
DIRECT
INPUT
Connects directly to external equipment
without using modules. Unbalanced
9
TERMINAL 10k ohms.
EARTH
Normally connects to a record player's
TERMINAL ground.
10
—
—
1
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Output Connections P-906A, P-912A
Installation
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.
•
•
Do not block cover ventilation holes.
The amplifier should not be placed in areas;
1. with poor ventilation.
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.
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.
•
When connecting speakers to any one of the outputs of 8 O, 25V
or 70V (BALANCED TRANSFORMER OUTPUT);
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.
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.
Place the LOW—CUT
SWITCH in "CUT" position
• When connecting speakers to the 4 output. (UNBALANCED
DIRECT OUTPUT);
— 3 —
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Operation
Rack Mounting
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.
To mount the amplifier in a standard 19-inch equipment rack, use
the MB-931 Rack-mounting Bracket accessory.
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.
Remove 4 screws securing case.
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.
Fix the MB-931 with attached 4 screws.
The length of the screws should not
exceed 12mm (1/2 inches).
MB-931
(Silver)
(OPTION)
Continuous signals
When the power amplifier is used in combination with a mixer pre-
amplifier, adjust the total gain at the mixer preamplifier with the
gain setting of the power amplifier at maximum.
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.
•
Output Fuse
Each amplifier has an output fuse to protect the amplifier from
short-circuiting at the output or overloading. Check the fuse when
speakers connected do not sound even if the meter deflects
normally. If the fuse blew, replace with the same type fuse after
confirming the following points.
(1) Speaker cables are not short-circuited or the load does not
exceed the rating specified.
(2) Wiring is correctly done at the output terminal board.
Servicing
•
Unpacking
Upon receipt of the amplifier shipment, please inspect for any
damage incurred in transit. If damage is found, please notify your
local TOA representative and the transportation company
immediately.
State date, nature of damage, whether any damage was noticed on
the shipping container, prior to unpacking. Please give waybill
number of shipping order.
•
Failure
Should amplifier fail, contact your nearest TOA authorized con-
tractor or service center.
— 4 —
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Specifications
P-906A
P-912A
Power amplifier
Type
120 watts RMS
Output Power
60 watts RMS
(D) 20—20,000Hz 0.5%THD
(T) 50—20,000 Hz 0.5% THD
Power Band Width
(D) 20— 20,000 Hz, ±1 dB
(T) 20— 15,000 Hz, ±1 dB
Frequency Response
+1dB
—3db
(T)20—20,000Hz,
0.01% at 1 kHz, rated output
Total Harmonic Distortion
Inputs
One Input Port
One Direct Input
Note
:
Port accepts any input module except T-01, which cannot be used.
Use of direct input prohibits use of modular input port.
:
Input Port
:
100 mV or 1,000 mV (Switchable)/10k ohms
100 mV or 1,000 mV (Switchable)/10k ohms
InputSensitivity/Impedance
Direct Input
:
Outputs
(D) - Direct
(T) - Transformer
Main (T) : 8 ohms, 25 & 70 volts, balanced
Main (D): 4 ohms, unbalanced
Output Regulation (1 kHz)
(D) Less than 0.5 dB, no load to full load
(T) Less than 1.0 dB, no load to full load
Input level switch in 0 dBv (1,000 mV) position
:
108 dB
Signal to Noise Ratio
Input level switch in -20 dBv (100 mV) position : 90 dB
(Band Pass 20 — 20,000 Hz)
1 Input gain control
1 Input level switch
Controls
1 Power ON/OFF switch
1 Low-cut switch (60 Hz, 6 dB/octave)
Indicator
1 Illuminated VU meter
Self-protection, with 2 AC fuses (1 inside) and 1 output fuse
Protection
Inputs . . . . . . . . . . . . . . . . .Card-edge connector and screw-terminal strip
Outputs . . . . . . . . . . . . . . . .Screw-terminal strip
AC outlet . . . . . . . . . . . . . . .3-pin grounding type
AC power cord/plug . . . . . . . . .SJT, 3-prong type
Connectors
Power Consumption
Temperature Range
AC 1 20 volts, 60 Hz, 100 watts
AC 120 volts, 60 Hz, 180 watts
-10°C to+60°C (12°F to 140°F)
145 (5.71") x 420 (16.54") x 315 (12.40")
Rack-mounting space size "3U" (5.21")
Dimensions in mm (inches)
(high) x (wide) x (deep)
14.2kg (31.2 Ibs.)
Weight (without input modules)
Color
10.4 kg (22.9 Ibs.)
Silver
Output disconnected for approx. 5 sec after switching power on.
Other Features
Specifications are subject to change without notice.
— 6 —
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Plug-in Modules and Accessories
(OPTION)
(INPUT CONNECTIONS, T-01 OUTPUT CONNECTION)
The TOA PLUG-IN MODULES are suitable for TOA 900 SERIES
MIXER POWER AMPLIFIERS A-901A, A-903A, A-906A, and
A-912A MIXER PREAMPLIFIER M-900A, and POWER AMPLI-
FIERS P-906A, P-912A and P-924. Owing to wide selection of
MODULES, the desired applications will be obtained. The various
types of connectors can also meet the needs of equipment to be
connected. MICROPHONE PREAMPLIFIER H-01 series, H-21 and
H-31 incorporates controls for high-cut, low-cut and gain, H-02
series, H-22, H-32 and H-03 series controls for low-cut and gain.
A gain control is built in MAG. PHONO PREAMPLIFIERS E-01
and E-11 series, AUXILIARY PREAMPLIFIERS X-01 and X-11
series and X-21, PAGING INPUT I-01 and LINE OUTPUT T-01
series. T-01 series is an output module with transformer, serving
as a line output for recording, etc..
PAGING INPUT I-01 is specially designed to associate with TOA
INTERCOM SYSTEMS. It accepts paging signals from the intercom
station.
A group of special signal generating modules is also available for
catching-attention before announcement and testing within the total
system. ALL PLUG-IN MODULES have handles on their front for
easy insertion and removal.
Features:
1. Wide dynamic range
2. Low noise and distorition
3. Wide frequency response
4. Built-in remote volume control circuit (available for models
having 20's in its model number such as H-21)
5. Built-in muting circuit to mute incoming signal when MUTE
TERMINAL is grounded, (available for modules having 10's in
its model number such as X-11)
6. Built-in muting circuit to deliver output signal when MUTE
TERMINAL is grounded, (available for modules having 30's in
its model number such as H-31)
7. Built-in signal activated muting function (L-41)
8. Presettable gain control (except for B-01, B-11, L-01 and L-11)
9. Microphone modules furnished with tone controls (H-01, H-02,
H-21, H-22, H-31, H-32 and H-03)
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TOA NEW 900 SERIES
Plug-in Modules
• FORNT PANEL CONTROLS AND FEATURES
Modules with built-in controls are provided in the following five
types.
• SPECIFICATIONS IN COMMON
LOW-CUT FILTER
CONTROL
330Hz, 6dB/oct
(max. attenuation)
This provides flat characteristics at full
CW position and attenuation in low
frequency by turning CCW. Adjust it to
obtain proper tone quality. With low-cut,
tonebecomesclear.
This adjusts MUTE delay time which is
the duration from signal input to its
output. Turn CW to shorten and CCW
to lengthen the time.
This provides flat characteristics at full
CW position and attenuation in high
frequency by turning CCW. Adjust it to
obtain proper tone quality. With high-
This adjusts gain. Turn clockwise (CW)
to increase and counterclockwise (CCW)
to reduce gain.
Set the gain as low as possible, thereby,
noise can be reduced, and the maximum
permissible input level is raised.
GAIN CONTROL
Load impedance
Mounting
:
:
10k-ohms
Card-edge connector
Dimensions in mm (inches)
(H) x (W) x (D)
:
78(3.07)x35(1.38)x88(3.46)
MUTE DELAY
CONTROL(I-01S)
SENSITIVITY
This adjusts sensitivity for muting other
modules having MUTE function. Turn
CW to raise and CCW to lower sensitivity.
Setting position should depend on the
equipment connected with L-41S.
The left figure shows nominal
setting of controls.
CONTROL(L-41S)
HIGH-CUT FILTER
CONTROL
4.2kHz, 6dB/oct
(max. attenuation)
NOMINAL POSITION
MARK
cut, tone becomes soft.
— 9 —
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TOA NEW 900 SERIES
Block Diagrams (Plug-in Modules)
— 10 —
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Operation and Connections (Plug-in Modules)
•T-01 SERIES (BALANCED 600-ohm LINE OUTPUT MODULES)
•
E-11, X-11, L-11, B-11 Series, H-31 and H-32 (with mute)
This series of modules, of rated output level 1 volt, is used for
transmitting mixing signals of amplifiers to external equipment and
as a REC out.
Connections
(M-900A, A-903A, A-906A, A-912A)
It is provided with a presettable gain control.
T-01 Series should be used exclusively for TOA 900 series, A-903A,
A-906A, A-912A and M-900A. Use it only in Input Port #5 or #6 of
the above models. It will not operate when connected into other
PORTS.
Remoto switch
Mute
Terminal
Approx. 5 seconds after power has been supplied to these modules,
the output signal is transmitted.
Operation
When the switch is closed,,
a. the signal fed to E-11, X-11, L-11 and B-11 are attenuated by
approx. 60dB. Accordingly a microphone can have a priority at a
time of announcement.
•S-01 (1,000Hz SINE WAVE)
Connections
b. the signal fed to H-31 and H-32 are delivered to the amplifier.
(While the switch is opened, the signals are attenuated.)
Remote switch
It is operated by closing the remote
switch.
•
L-41 (with signal activated muting facilities)
When this module accepts the input signal, the mute terminal is
grounded automatically without connection of the remote switch
to the MUTE TERMINAL. It causes the other modules with mute
function, like X-11, to be muted.
•
S-02 (YELP AND BUZZER)
Connections
Yelp signal
Accordingly the signal fed to the L-41 can have a priority.
Remote switch
•
H-21, H-22 and X-21 (Remote volume control facilities)
Each signal is generated by closing cor-
responding remote switch.
Connections
Remote switch
Potentiometer
10k
•
S-03 (ONE-TONE CHIME AND CONTINUOUS ONE-TONE
CHIME)
Remote
volume
control
CONNECTIONS
One-tone chime
Remote switch
Input Connection
By closing the remote switch, chime
sounds once.
Operation
Continuous one-tone chime
Preset the gain control of module and the input volume control of
the corresponding input so that an appropriate sound level may be
obtained through the remote volume control.
Remote switch
By closing the remote switch, one-tone
chime sounds continuously during the
closure of the switch.
— 11 —
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