Toa M-9000, M-900A Operation & Instruction Manual

Operation Instruction Manual

TOA NEW 900 SERIES

MIXER PREAMPLIFIER

Features

1 6-channel mixer preamplifier
2 Wide frequency response; 20 — 20,000Hz, ± 1dB

3 Low distortion and noise
4 Parallel operation of two mixer preamplifiers
5 Headphone output
6 Bass and treble controls
7 Tone defeat switch
8 Output on-off switch
9 VU meter range switch (selectable 4dBm/18dBm)

10 A full range of plug-in modules
11 Balanced and transformer-isolated output of 150/600 ohms
12 Portable or rack-mounting type

M-900A

General Description

The TOA M-900A Mixer Preamplifier controls and mixes up to six
independent input signals and delivers up to +20dBm of output
power. Optional plug-in modules are a vai lab le for use with t he M­900A to provide versatility for a wide choice of operating applica­tions. Edge connectors in the rear of the unit permit selection from
a wi de range of TOA plug-in modules: the H-01 series, H-02 series
and H-03 series Microphone Preamplifiers, the E-01 and E-11 Mag.
Phono Preamplifiers for magnetic phono inputs, the X-01 series and
X-11 series Auxiliary Preamplifiers for high-level sources, the B-01
series and B-11 series Bridging Transformers for bridging high­impedance lines, the L-01 series Line Matching Transformers for
matching 600-ohm lines, the 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-ohm lines and the S-01, S-02
and S-03 Tone Generators for generating attention-getting signals
and 1kHz sine wave for testing within the total system. Sources fed
to

particular
at MUTE TERMINAL on the rear. To perform this function,
Module E-11, X-11 series or B-11 series is required.
The TOA M-900A Mixer Preamplifier has a balanced and trans­formerisolated output for operation with 600-ohm or 150-ohm
loads.
Other features include a tone defeat switch, an output on/off
switch, connections for parallel coupling of another M-900A or
Mixer Power Amplifiers A-903A, A-906A or A-912A, and monitor­ing by visual and/or audio means.

input

module

accessories

are

muted

by

short-circuiting

Toa Electric Co., Ltd.

KOBE, JAPAN

133-02-736-1

Printed in Japan

Front Panel Controls and Features

Rear Panel Controls and Features

Item

POWER ON-OFF

1

SWITCH

METER

2

INPUT VOLUME

3

CONTROLS

BASS CONTROL

4

Name

Adjust gain of INPUT #1-#6

Turn clockwise (CW) to boost and

Function/Description

Appli es line power. Two-position
pushbutton switch for on-off modes.

Indicates the output level of the

amplifier. At rated output, it shows

0 VU (continuous sine-wave signal

input).

When power is turned on, meter

illuminates.

respectively.

Adjust bass response.

counterclockwise (CCW) to
attenuate the bass response. Tone is

flat at center.

TREBLE

5

CONTROL

TONE SWITCH

6

MASTER

7

VOLUME

CONTROL

OUTPUT SWITCH

8

Adjust treble response.

Turn CW to boost and CCW to

attenuate the treble response. To ne is

flat at center.

Selects IN/DEFEAT of the BASS and
TRE BL E CONTROLS. When this

button is depressed

and TREBLE Controls are active.
When pressed again
become inactive to make tone fl at .
(DEFEAT)

Adjusts overall gain of unit.

This is an output ON/OFF switch.

When pressed

obtained at the output terminal.

When pressed again

signal is obtained.

HEADPHONE

9

JACK

HEADPHONE

10

VOLUME

CONTROL
VU RANGE

11

SWITCH

Usually

set the
amplifier's rated output is +4dBm.
Place it in "18dBm" position when more output is

provided.

Connects to headphones with
impedance of more than 8

Adjust the volume for headphones.

Turn CW to increase.

Selects meter-sensitivity.

When set to "4dBm" position, the
meter shows 0 VU if the output level
of amplifier is +4dBm. When set to

"18dBm," it shows 0 VU if the

output level is +18dBm.

switch

to

"4dBm"

position,

the BASS

they

output signal is

no output

since

the

Item

1

AC POWER

SUPPLY CORD

AC OUTLET

2

(Unswitched)

AC FUSE

3

(250V 0.3A)

OUTPUT

4

TERMINALS

MODULE INPUT

5

PORTS

AUX O UT

6

7

BRIDGING
INPUT/OUTPUT

MUTE

8

TERMINAL

EARTH

9

TERMINAL

Name

Function/Description

Connects to power source.

Provides AC power for auxiliary
equipment with power consump tio n
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 power a mplifier(s).

Accept PLUG-IN MODULES which

are optionally available. Choose the
desired modules according to
application.

Serves as a sub-output for connecting
other equipment having input

impedance of more than 10k

as a tape recorder.

This terminal is used as a mixing bus.

Mixing is achieved when the similar
terminal of another amplifier is
connected to this terminal.

such

The output level take n from this

terminal is independent of the

MASTER VOLUME CONTROL ,

BASS and TREBLE CONTROLS, so
that the terminal can also be used as
recording output. The input

impedances of the equipment to be

connected here should be 10k
higher.

With modules employing muting
function, which are optionally
available, the input signals fed to the
modules are muted by short-circuiting

at this terminal.

Normally connects to a record

player's ground.

or

— 1 —

Input Connections

Output Connections

This amplifier has six INPUT PORTS for PLUG-IN MODULES.

•

Select the desired ones for each application.

Plug the modules into INPUT PORTS, sliding them between the

•

guide rai ls, and secure each with two screws.

When not all INPUT PORTS are occupied, cover the vacant

•

PORTS with blank panels, and secure them with screws.

PLUG-IN MODULES are provided in the following:

•

Balanced low impedance microphone
preamp module (w ith pr esettable low-cut

filter, high-cut filter and gain controls)

Balanced low impedance microphone

H-01,

H-21,

H-31

H-02,H-22, H -32

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)

Balanced 10k
Balanced 600

transformer module

bridging transformer module

line matching

X-01,

L-01,

E-01 , E-11

X-11,

X-21

B-01,

B-11

L-11,

L-41

Balanced paging input module

(with presettable gain control and MUTE Delay)

Balanced 600

(with presettable gai n control)
Signal tone generator module

(with presettable output level control)

line output module

1 kHz sine wave
Yelp and buzzer

One-tone chime and continuous one-tone chime

T-01

S-01
S-02
S-03

I-01

Connect power amplifier(s) to the output terminal of M-900A.

•

Select 600
mina l, to match the input impedance of amplifier(s).

600-ohm Connection

4
3
2

1

GND

150-ohm Connection

4
3
2

1

GND

AUX

OUT

•

For this connection, use a Phone Plug (Double pole) with two-wire

shielded cable.

or 150

Strap terminals 2 and 3 .

Strap terminals 1 and 2 , 3 and 4 .

connection, provided at the output ter-

Hot

Common
Earth

Hot

Common
Earth

Hot
Common
Earth

External equipment such as

tape recorders, etc.

*W

ith H-21, H-22 and X-21 modules employing volume remote
control functions, connecting a potentiometer (10k ohms) to the
terminal of any of these modules permits the sound volume to be

remotely controlled by means of the connected potentiometer.

* H-31 and H-32 modules i ncorporate muting functions. If a switch

is connected to MUTE TERMINAL on the rear panel of the ampli-

fier and closed, these input signals can be passed through. When

the switch is opened, the input signal is muted.

E-11 , X-11 , B-11 and L-11 modules incorporate muting functions.

*

If a switch is connected to MUTE TERMINAL on the rear panel

of the amplifier and closed, these input signals can be muted.

*

L-41 incorporates signal activated muting function. Incoming

input signal causes mute terminal to be grounded.

* T-01 is used to feed out mixed signals to extern al equipment.

*T-01 should be inserted only in INPUT PORT #5 or #6.

(See PLUG-IN MODULES for details)

— 2 —

Operation

Installation

When all connections are completed, turn power switch on. Then,
the meter is illuminated. Approximately 5 seconds after switching
power on, the M-900A comes into operation.

VOLUME CONTROL

Set VU RANGE SWITCH to "4dBm" position and place OUTPUT
SWITCH in "ON" position. While observing the deflection of the

meter, control each input volume and master volume controls to
obtain a proper output level.

The swinging range of the pointer on the meter is recommended to

be within the range as indicated in the drawing. Also, adjust gain

(volume control) of the connected power amplifier to obtain similar

readi ng on the meter of the power amplifier.

In connecting a power amplifier with lower gain, so that the

mixer preamplifier is required to be used with its higher output,

the VU RANGE SWITCH shall be set to 18dBm.

ADJUSTMENT OF TONE QUALITY

When adjusting tone quality, place the TONE SWITCH in "IN"

position, thus activating the BASS and TREBLE CONTROLS.

Each control provides frequency-response characteristics of flat in

center, boost in CW and attenuation in CCW positions.

When tone controls are unnecessary, place the TONE SWITCH

in "DEFEAT" mode.

Do not block cover ventilation holes.

•

The M-900A 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.

MONITOR

Monitoring is possible by the use of headphones.
Connect the headphones to HEADPHONE JACK, and adjust the
monitoring level by using the HEADPHONE VOLUME CONTROL.

OUTPUT ON/ OF F SWITCH

ON/OFF status of the output can be controlled by the OUTPUT
SWITCH, and output can be obtained at the output terminal and
auxiliary output ja ck after confirming the content of the signal by

monitoring with headphones.

— 3 —

Rack Mounting

Servicing

To mount the M-900A in a standard 19-inch equipment rack, use

the MB-921 Rack-mounting Bracket accessory.

Remove 4 screws securing case.

MB-921 (Silver)

(OPTION)

Fix the MB-921 with attached 4 screws.
The length of the screws should not

exceed 12mm (1/2 inches).

•

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 im-

mediately.
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.

— 4 —

Block Diagram M-900A

— 5 —

Specifications M-900A

Type

Output Power

Power Band Width

Frequency Response

Total Harmonic Distortion

Inputs

Input Sensitivity/Impedance

Outputs

Output Regulation (1 kHz)

Signal to Noise Ratio
(Band

Pass

20 -

20,000

Hz)

Tone Controls Centered

Tone Controls

Controls

Indicator

Protection

Connectors

Power Consumption

Temperature Range
Dimensions in mm (inches)

(high) x (wide) x (deep)

Weight (without input modules)

Color

Standard Accessories

Other Features

6-channel mixer preamplifier

+4 dBm (Rated Output) +20 dBm (max. )

30 - 20,000 H z +20 dBm 0. 5% T H D
25 - 20,000 Hz +18 dBm 0.3% TH D

20 - 20,000 Hz , ± 1 dB

0.01% at 1kHz, +20 dBm output

Six Input Ports Each port accepts any input module

except T-01. Use T-01 only in port #5 or #6.

One Bridging Input/Output

Input Ports #1 to #6 : 100 mV/10k ohms

Bridging Input/Output: 100 mV/3.3k ohms

Main : Balanced, 1 50/600 o hm s
Phones. Unbalanced, 8 ohms (30 mW) to 600 ohms (200 mW)

Aux : Balanced, 10k ohms,+2 dBm

Less tha n 1.5 dB, no load to f ul l load

Master volume min. : 90 dB

Master volume max.: 77 dB

Bass; ±1 0d B at 100 Hz: Treb le; ±10dB at 10 kHz

6 Input gain controls 1 Master gain control

1 Bass tone control 1 Treble tone control

1 Headphone volume control
1 Output ON/OFF switch 1 VU meter range switch
1 Tone defeat switch 1 Power ON/OFF switch

1 Illuminated VU meter

Self-protection, with 1 AC fuse

Inputs #1 to #6
Bridging

Output

Headphone

Aux out

Mute

AC outlet

AC Power cord/plug

AC 120 volts, 60 Hz, 1 3 watts

-10°C to +60°C (12°F to 140°F)

101 (3.98") x 420 (16.54") x 265 (10.43")
Rack-mounting space size "2U" (3.46")

4.4kg (9.7 Ibs.)

Silver

2 Volume control covers

1 Mute terminal plug

Output disconnected for approx. 5 sec after switching power on

Muting Function: Accomplished by model E-11 , X-11, B-11

* Specifications are subject to change without notice.

Card-edge connector

RCA phono jack

Screw terminal strip

Phone jack

Phone jack

2P socket
3-pin grounding type

SJT, 3-prong type

— 6 —

TOA NEW 900 SERIES

Plug-in Modules and Accessories

(OPTION)

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.

(INPUT CONNECTIONS, T-01 OUTPUT CONNECTION)

Features:

1. Wide dynamic range

2. Low noise and distortion

3. Wide frequency response

4. Built-in remote volume control circuit (available for models
having 20's in its model number such as H - 2 1 )

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)

— 7 —

TOA NEW 900 SERIES

Plug-in Modules

• FORNT PANEL CONTROL S AND FEATURES

Modules with built-in controls are provided in the following five
types.

— 8 —

GAIN CONTROL

SENSITIVITY
CONTROL (L-41S)

NOMINAL POSITION

MARK

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.
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.

LOW-CUT FILTER
CONTROL

330Hz, 6dB/oct

(max. attenuation)

MUTE DELAY
CONTROL (I-01 S)

HIGH-CUT FILTER
CONTROL

4.2kHz, 6dB/oct
(max. attenuation)

* 0 dBv= 1 volt= + 2 dBm. * Specifications are subject to change without notice.

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,
tone becomes clear.
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 high­cut, tone becomes soft.

— 9 —

• SPECIFICATIONS IN COMMON

Load impedance : 10k-ohms
Mounting : Card-edge connector
Dimensions in mm (inches) : 78(3.07)x35(1.38)x88(3.46)

(H) x (W) x (D)

Block Diagrams (Plug-in Modules)

— 10 —

Operation

E-11, X-11, L-11, B-11 Series, H-31 and H-32 (with mute)

•

Connections

(M-900A, A-903A, A-906A, A-912A)

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.

b. the signal fed to H-31 and H-32 are delivered to the amplifier.

(While the switch is opened, the signals are attenuated.)

and

Connections

(Plug-i

n

Modules

)

T-01 SERIES (BALANCED 600-ohm LINE OUTPUT MODULES)

•

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

It is provided with a presettable ga in 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 Por t #5 or #6 of

the above models. It will not operate when connected into other

PORTS.
Approx. 5 seconds aft e r power has been supplied to these modules,

the output signal is transmitted.

S-01 (1,000Hz SINE WAVE)

•

out.

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 wit h mute
function, like X-11, to be muted.
Accordingly the signal fed to the L-41 can have a priority.

H-21, H-22 and X-21 (Remote volume control facilities)

•

Operation

Preset the gain control of module and the input volume control of
the corresponding input so that an appropriate sound level may be
obtained throug h the remote volume control.

It is operated by closing the remote

switch.

Each signal is generated by closing cor-

responding remote switch.

S-03 (ONE-TONE CHIME AND CONTINUOUS ONE-TONE

•

CHIME)

CONNECTIONS

By closing the remote switch, chime

sounds once.

— 11 —

By closing the remote switc h, one-tone
chime sounds continuously during the
closure of the switch.

• I -01S (BALANCED PAGING INPUT MODULE)

This module is used for connecting TOA intercom Systems (EXES)
for paging. By connecting this module to the exchange in place of
an intercom station, paging is possible. It is provided with a pre­settable gain control. The I-01S is applicable to the TOA EXES-

1000, EXES-5000 and EX-16 Intercom Systems.

CONNECTIONS

LMU (Line Modem Unit)

This unit is composed of a modulator to receive signals from
stations, a demodulator to send signals to the station and a scanning
circuit.
Summary Specifications of R and T Lines

R-line: Approx. 9mA DC plus audio signals of +30dBm max .

T-line: Approx. 9mA DC

HOW TO U SE:

Paging is possible fro m other station by dialing the station number

assigned to this module. To prevent a calling tone from being
sounded through the paging speaker, the module is designed to
override paging output during a period of time that the calling tone

signal is transmitted. The length of time to mute the paging output

is adjustable between zero and three seconds. During paging,

background music (the input signal fed to E-11, X -11, L-11 or B-11

module) is muted.

Optional Accessories

Rack-mounting Brackets Perforated Panel

MB-931A MB-921A

A-912A A-903A

P-906A
P-912A
P-924

(Silver) (Silver)

PF-911

Volume Control Cover

YA-910

(BLACK)

— 12 —

Schemiatic M-900 A