TOA Electronics W-912A, W-906A User Manual
OPERATING INSTRUCTIONS
NEW 900 SERIES
IN-WALL MIXER POWER AMPLIFIER
W-906A
W-912A
INPUT 1
POWER
ON
250V 3A 250V 6A
OFF
OFF MAX
INPUT 2 INPUT 3
AC FUSE
OFF ON
LOW PASS
OFF ON
HIGH PASS
OUT
63 125 250 500 1k 2k 4k 8k 16 k
63 125 250 500 1k 2k 4k 8k 16 k
IN
EQUALIZER
OUTPUT FUSE COMPRESSOR
INPUT 4 INPUT 5 INPUT 6 MASTER
12
6
0
6
12
12
6
0
6
12
900 SERIES
WALL AMPLIFIER
POWER PEAK
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.
1. GENERAL DESCRIPTION ............................ 2
2. FEATURES .................................................... 2
3. NOMENCLATURE AND FUNCTIONS
Front .............................................................. 3
Front (
viewed with the front cover removed
) .... 4
4. INSTALLATION AND CONNECTION .......... 5
5. SERVICING .................................................... 8
6. OPERATION ................................................ 8
7.
HOW TO USE VOLUME CONTROL COVER
.... 9
8. OUTPUT EQ CHARACTERISTIC ............. 10
9. BLOCK DIAGRAM .................................... 10
10. SPECIFICATIONS ..................................... 11
Accessories ................................................ 12
TABLE OF CONTENTS
2
1. GENERAL DESCRIPTION
The TOA W-906A and W-912A Mixer Power Amplifiers control and mix up to six independent input signals
plus two inputs with use of expanding kit. The W-906A delivers up to 60 W of output power and the W-912A
120 W. Optional accessory modules are available for use with the W-906A and W-912A to provide versatility
for a wide range of operating applications. Edge connectors at the bottom of the front panel permit the
selection of the TOA plug-in modules: The H-01 series, H-02 series, H-03 series, H-21 and H-22 Microphone
Preamplifiers, the E-01 series and E-11 series Mag. Phono Preamplifiers, the X-01 series, X-11 series and X21 Auxiliary Preamplifiers for high-level sources, the B-01 series and B-11 series Bridging Transformers for
bridging high-impedance lines, the L-01 series Line Matching Transformers for matching 600 Ω lines, I-01
Paging Input for combining with TOA Intercom Systems EXES-1000, EXES-5000 and EX-16, T-01 series Line
Outputs for matching 600 Ω lines 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. Other features include a
muting function. Sources fed to particular input module accessories are muted by short-circuiting at MUTE
TERMINALS on the front. To perform this function, Module E-11, X-11 series or B-11 series is required. Using
any of the modules H-21, H-22 and X-21 permits the input signal level to be controlled remotely by means of
an external potentiometer.
The W-906A and W-912A have a built-in one-octave graphic equalizer with 9 bands to tailor sound system
frequency response to room acoustics, reducing feed-back tendencies and improving intelligibility. A built-in
compressor circuit is provided to protect the output level from distortion as a result of excessive input and
keeps it constant. Compressor's threshold level can be adjusted.
The W-906A and W-912A Mixer Power Amplifiers have output terminals to match 4 or 8 Ω speaker systems,
or speaker distribution system may be connected to the 25 or 70 V terminals. User's (blank) space is provided
for additional functions to be made by the customers. The expanding kit (optional) may be loaded in this space
when the number of input is increased. Protection against tampering is assured by means of a key-locked
hinged door. The W-906A and W-912A can be mounted in any four-inch wall with of the BX-9F Flush
Mounting Black Box. On-wall mounting is also possible with the BX-9S Surface Mounting Box.
2. FEATURES
• 6-channel mixer power amplifier
• Expandable to 8-input
• Output power: 120 W for W-912A, 60 W for W-906A
• Wide frequency response: 30 to 20,000 Hz ±1dB
• Low distortion and noise
• Excellent output regulation
• Built-in one-octave equalizer
• Built-in compressor
• Self-protection circuitry design
• Separate output terminals: 4 and 8 Ω, 25 and 70 V
• Extra space for customizing
• LED pilot light
• LED peak indicator
• Full range of plug-in modules
• Flush and surface mounting
3
3. NOMENCLATURE AND FUNCTIONS
[Front]
1. Power switch
Applies line power. Two-position push button
switch for on-off modes.
2. Input volume controls
Adjust gain of input 1 – 6 respectively.
3. Master volume controls
Adjust overall gain of unit.
4. Modules (optional)
Select appropriate modules according to the
application.
5. Compressor control (limiter)
Setting the control switch to OFF position
bypasses the compressor circuit and turning it
clockwise will reduce the limiter level (will limit the
output).
6. Equalizer switch
Place this switch in the IN position to activate an
equalizer.
7. High-pass filter switch
Place this switch in the ON position to cut off
unnecessary low frequency.
8. Low-pass filter switch
Place this switch in the ON position to cut off
unnecessary high frequency.
9. Equalizer controls
9 band filters. 12 dB boots and cut at each center
frequency.
10. Power indicator
Comes on when power is switched on.
11. Peak indicator
Comes on when the output signal reaches the
rated output power level.
12. Output fuse
Prevents excessive current flow.
W-906A: 250 V, 6 A
W-912A: 250 V, 10 A
13. AC fuse
Prevents excessive current flow.
W-906A: 250 V, 3 A
W-912A: 250 V, 5 A
14. Blank panel (user's space)
The space of 103 (w) x 63 (h) x 95 (d) mm is
provided. An optional expanding kit may be
loaded in this space.
15. Equalizer security cover
Prevents inadvertent changes of the equalizer
controls set at proper level.
16. Key-locked door
Prevents tampering.
INPUT 1
POWER
ON
250V 3A 250V 6A
OFF
OFF MAX
INPUT 2 INPUT 3
AC FUSE
OFF ON
LOW PASS
OFF ON
HIGH PASS
OUT
63 125 250 500 1k 2 k 4k 8k 16 k
63 125 250 500 1k 2 k 4k 8k 16 k
IN
EQUALIZER
OUTPUT FUSE COMPRESSOR
INPUT 4 INPUT 5 INPUT 6 MASTER
12
6
0
6
12
12
6
0
6
12
OFF ON
LOW PASS
OFF ON
HIGH PASS
OUT
63 125 250 500 1k 2k 4 k 8 k 16k
63 125 250 500 1k 2k 4 k 8 k 16k
IN
EQUALIZER
12
6
0
6
12
12
6
0
6
12
900 SERIES
WALL AMPLIFIER
POWER PEAK
1
2
4
10
11
12
13
15
Equalizer Section
3
14
16
5
6 7
8
Equalizer Section
9
4
[Front] (viewed with the front cover removed)
17. AC power cord
Connects to power source.
18. Speaker output terminals
Connects to speakers.
19. Output terminals
Select output impedance with this terminal.
20. Low-cut switch
Cuts off unnecessary low frequency.
21. Module input ports
Accept PLUG-IN MODULES which are optionally
available. Module selection is determined by
application.
22. Bridging input/output
This terminal is used as a mixing bus. Mixing is
achieved when the similar terminal of another
amplifier is connected to this terminal. The output
level taken from this terminal is independent of
the all CONTROLS (except INPUT VOLUME
CONTROLS) so that the terminal can also be
used as recording output. The input impedances
of the equipment to be connected here should be
more than 10 kΩ.
23. Mute terminal
With modules employing muting function, which
are optionally available, the input signals fed to
the modules are muted by short-circuiting at this
terminal.
24. Cord clamp
Clamps off lead wires from module inputs, mute
terminals and bridging input/output terminals.
INPUT 1
POWER
ON
250V 3A 250V 6A
OFF
OFF MAX
INPUT 2 INPUT 3
AC FUSE
OFF ON
LOW PASS
OFF ON
HIGH PASS
OUT
63 125 250 500 1k 2 k 4k 8k 16 k
63 125 250 500 1k 2 k 4k 8k 16 k
IN
EQUALIZER
OUTPUT FUSE COMPRESSOR
INPUT 4 INPUT 5 INPUT 6 MASTER
12
6
0
6
12
12
6
0
6
12
Junction Box
20
21
19
23
24
22
18
17
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