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Operating Instructions
TOA 900 SERIES II
POWER AMPLIFIER
P-906MK2 P-912MK2 P-924MK2
P-906MK2 P-912MK2
P-924MK2
THE LIGHTNING FLASH WITH ARROWHEAD WITHIN A TRIANGLE IS INTENDED TO TELL THE USER THAT PARTS INSIDE THE PRODUCT ARE A RISK OF ELECTRIC SHOCK TO PERSONS.
TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
THE EXCLAMATION POINT WITHIN A TRIANGLE IS INTENDED TO TELL THE USER THAT IMPORTANT OPERATING AND SERVICING INSTRUCTIONS ARE IN THE PAPERS WITH THE APPLIANCE.
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.
TOA Corporation
Contents
General description Features Nomenclature Front panel Rear panel Input connections Output connections Rack mounting Operation Volume adjustment Installation Servicing Specifications Appearance (P-906MK2/P-912MK2) Appearance (P-924MK2)
2 2 3 4 5 6
7
8 8 8 8 9
10 11
General Description
The TOA P-906MK2, P-912MK2 and P-924MK2 Power Amplifiers deliver up to 60 watts, 120 watts and 240 watts of power respectively at less than 0.5% total harmonic distortion (THD) from 20 to 20,000 Hz (transformerless 4-ohm output). The power amplifiers have a high-impedance direct input and an input port (edge connector) to accept one plug-in module. Module selection is determined by application among the TOA plug-in modules. The power amplifiers have a low-cut switch for a cutoff frequency of 60 Hz, and an input-level switch for input sensitivity of 1V (0 dBV) or 100mV (20 dBV). Output terminals provide connections for 4-ohm and 8-ohm speakers, plus 25-volt and 70-volt speaker distribution outlets. With plug-in modules, the power amplifiers may be used as a PA amplifier. The power amplifiers can be rack mounted by using optional rack mounting bracket MB-25B(P-906MK2, P-912MK2) and MB-35B(P-924MK2). The optional perforated panel PF-511 provides suitable ventilation, finished in color to match the power amplifiers.
Features
1. Wide frequency response : 20 ~ 20,000 Hz ± 1 dB 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 ohms, 8 ohms, 25 and 70 volts 7. Input level switch (selectable 1000 mV/100 mV) 8. Portable or rack mounting type
2
Nomenclature
Front Panel
P-906MK2, P-912MK2
P-924MK2
Power Switch
Applies line power. Two-position push button
Peak Indicator LED
Red LED lights when amplifier approaches
switch for on/off modes.
Power Indicator LED
Green LED lights when the power is switched "ON". Signal Indicator LED Green LED lights when more than -30 dB signal level is fed to the inputs by means of the master volume control.
clipping level. If steady lit, the input level control should be turned down until the LED flashes. Protection Indicator LED Remains lit for about 5 seconds after power switch is turned ON. Master Volume Control Adjust gain of input.
Normal Indicator LED
Yellow LED lights when fed to the proper signal level.
3
Rear Panel
P-906MK2, P-912MK2
P-924MK2
AC Power Cord
Connects to power source. AC Outlet (Unswitched)
Provides AC power for auxiliary equipment with power consumption of up to 500W.
Input Level Switch Selects input sensitivity. Place in "1V" (0 dBV)
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.
Impedance Select Switch
Selects the desired impedance. Enables unbalanced output of low impedance when this switch is set to "DIRECT".
Direct Input Terminal
Connects directly to external equipment without
Output terminals
Connect to speakers. Module Input Port Accepts optional PLUG-IN MODULES. Application determines type of module. For details, refer to Plug-in Module Instruction Manual. Low-Cut Switch Cut off unnecessary low frequency.
using modules. Unbalanced 10k ohms. AC Fuse (250V, 7A)
DC Fuse DC Fuse (250V, 8A) (250V, 8A)
Protects amplifier from excessive current drain.
Replace only with same type fuse. Refer to qualified service personnel if fuse blows repeatedly.
4
Input Connections
Two types of input terminals are provided on the rear for input connections.
(1) 2P terminal (marked HOT, COM) 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. DIRECT INPUT TERMINAL and MODULE INPUT are not usable simultaneously.
Plug the modules into the 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-906MK2, P-912MK2 or P-924MK2 is used in combination with a mixer preamplifier or serves as an incremental power amplifier, normally place INPUT-LEVEL SWITCH in "1V (0 dBV) position.
CAUTION: Modules should not be inserted or removed while the amplifier is turned on.
5
Output Connections
The speaker outputs of the amplifier are 4 ohms, 8 ohms, 25V and 70V. Connect speakers to any one of these outputs. Class 2 wiring may be used.
There are two types of output ; 8 ohms, 25V and 70V via output (matching) transformer 4-ohm direct output. The connecting method differs in each case. Refer to the following diagrams.
Note : Impedances indicated below imply total speaker system (load) impedances.
To connect speakers to outputs of : 8 ohms, 25V or 70V (BALANCED OUTPUT)
(P-906MK2/P-912MK2)
10.4-ohm(P-906MK2)/
83-ohm(P-906MK2)/
8-ohm
5.2-ohm(P-912MK2)
25V line
41-ohm(P-912MK2) 70V line
Loosen the screw.
Place the impedance switch in 8-ohm position.
Tighten the screw.
(P-924MK2)
8-ohm
2.6-ohm 25V line
21-ohm 70V line
Insert shorting bar between 4
and OT lN.
Note : Low-cut switch should be in "CUT" position. Cut off unnecessary low frequency in TRANS OUTPUT to obtain best acoustic condition. The 900MK2 series amplifiers are characteristically flat even in the low frequency range. Thus, in TRANS OUTPUT the acoustic effect and frequency-response characteristics may be altered.
6
To connect speakers to 4-ohm output (UNBALANCED DIRECT OUTPUT)
(P-906MK2/P-912MK2)
4-ohm
Loosen the screw.
Place the impedance switch in 4-ohm position.
Tighten the screw.
(P-924MK2)
Remove shorting bar.
4-ohm
Rack Mounting
To mount the amplifier in a standard 19" equipment rack, use the optional MB-25B, MB-35B rack mounting bracket.
Remove 4 screws securing case.
MB-25B (P-906MK2, P-912MK2) MB-35B (P-924MK2)
Amplifier
Fix the brackets with attached 4 screws. The length of screws should not exceed 12mm (1/2").
PF-511 perforated panel (1-unit size)
Use the perforated panel PF-511 to provide space for ventilation, when two or more units are mounted in an equipment rack. Contact your local TOA dealer for the perforated panel PF-511.
7
Operation
After all connections are made, turn power switch ON, illuminating the Power Indicator LED. The amplifier comes into operation approximately 5 seconds after the power is turned on.
Volume Adjustment
Obtain desired output level by adjusting the master volume control. For normal music playing or announcement, adjust the master volume control until the normal LED intermittently lights. Sound quality is deteriorated when the peak LED remains lit. When the power amplifier is used in combination with a mixer preamplifier, adjust total gain at the mixer
preamplifier with the gain setting of power amplifier at maximum.
Never block ventilation holes. The amplifier should never be placed in areas exposed to direct sunlight. with high humidity or dust levels. with high ambient temperatures.
susceptible to vibration. with poor ventilation. adjacent to heat-generating equipment.
CAUTION : Do not remove the case or you may encounter an electric shock.
Note : When the temperature of heat sink exceeds 105 °C the protection circuit is activated and the output is disconnected from the circuit. Output is automatically restored when the temperature return to normal operating parameter.
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 contractor or service center.
8
Specifications
P-906MK2
Type
Output Power Power amplifier
60W RMS
(D) 20 ~20,000 Hz, 0.5% THD (T) 50 ~20,000 Hz, 0.5% THD (D) 20 ~20,000 Hz, ± 1 dB
P-912MK2
P-924MK2
120W RMS
(D) 240W RMS, (T) 220W RMS
Power Band Width
Frequency Response
(T) 20 ~15,000 Hz, ± 1 dB, (T) 20 ~20,000 Hz, +1 dB, -3 dB
Total Hamonic Distortion Inputs
0.01% at 1 kHz, rated output
One Input Ports : Port accepts any input module except T-01. One Direct Input Note : Use of direct input prohibits use of modular input port. Input Port : 100 mV or 1000 mV (switchable)/10k ohms Direct Input : 100 mV or 1000 mV (switchable)/10k ohms Main (T) : 8 ohms, 25 & 70 volts, balanced Main (D) : 4 ohms, unbalanced (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 (1000 mV) position : 108 dB Input level switch in -20 dBV (100 mV) position : 90 dB
Input Sensitivity/Impedance Outputs (T)=Transformer (D)=Direct Output Regulation (1 kHz)
Signal to Noise Ratio (Band Pass 20 -20,000 Hz)
Controls
1 1 1 1
Input gain control Input level switch Power ON/OFF switch Low-Cut switch
Indicators Protection
1 Power LED, 1 Protect LED, 1 Signal LED, 1 Normal LED, 1 Peak LED Self-protection, with AC fuse (inside) Input Output AC outlet AC power cord/plug 100W
-10°C~+60°C [12°F~140°F]
Self-protection, with 2AC fuses (1 inside) and 2DC fuses
Connectors
Card-edge connector and screw-terminal strip Screw-terminal strip 3-pin grounding type SJT, 3-prong type
180W 120V/3A
Power Consumption
Temperature Range
Dimensions (W) x (H) x (D)
Weight Color
Standard Accessories Other Features
420 x 99.1 x 358 mm
[16.5 x 3 . 9 x 14.1 in.]
9.1 kg [20.1 Ib.]
420 x 151.3 x 334.2 mm [16.5 x 6.0 x 13. 2 in.] 19.5kg [43 Ib.]
10.9kg [24.0 Ib.]
Black
1 Volume control cover (YA-920) Output disconnected for approx. 5 seconds after switching power on.
* Specifications are subject to change without notice.
9
Appearance (P-906MK2/P-912MK2)
Front View
420
Rear View
Top View
Side View
320
10
17
358
Appearance (P-924MK2)
Front View
420
Rear View
Top View
Side View
298.5
11
17
334.2
TOA Corporation
KOBE, JAPAN
PRINTED IN TAIWAN
133-12-116-60