Bogen MTA10 Operating Manual

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MODEL MTA'IO

TRANSISTOR
10 WATT PUBLIC ADDRESS AMPLIFIER

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INSTALLATION ANI] OPERATING MANUAL

READ THOROUGHLY BEFORE OPERATING EQUIPMENT

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INTRODUCTION

The model MTAlO is a general purpose 10 watt public
address amplifier. Separate microphone and auxiliary inputs
and volume controls permit mixing of the two inputs. A treble
control is provided for adjusting tonal balance. A Speech-

Music switch provides optimum speech response.

Outputs are provided for all standard speaker impedances
and for operation with 25 volt and 70 volt long line speaker
systems.

TECHNICAL SPECIFICATIONS

POWER O UTPUT:
w atts peak.

10 watts at less than 3% distortion; 20

FREQUENCY RESPONSE: 50 to 20.000 cycles, :2 db.

POWER RESPONSE: 12 db, 50 to 16.000 cps at l0 watts
With less than 5% distortion.

HUM & NOISE:
MIC INPUT: 60 db (weighted) below rated power.

AUX INPUT: 80 db (weighted) below rated power.
GAIN:

MIC INPUT: 105 db

AUX INPUT: 95 db
SENSITIVITY:

MIC INPUT: 0.4 millivolts

AUX INPUT: 0.2 volt

l auxiliary (high
WMT-I.

INPUTS: l microphone (low impedance).
impedance-high level). 1 input for optional
(500/600 ohm) transformer. I. bridging input.

OUTPUTS: 4. 8; balanced 16 ohms; 25 volts (62 ohm) bal-
anced C.T.; 70 volts balanced (500 ohm).

TONE CONTROL ACTION: TREBLE (10 KC) -23 db.

CONTROLS: Microphone Volume, Auxiliary Volume, Treble,
Speech Music filter Switch, and Power Switch.

TRANSISTORS erIODES. 5 transistors and dual diode.

POWER CONSUMPTION: 30 watts.

DIMENSIONS: 10 5/8 wide, 5" high, 5V2" deep.

SHIPPING WEIGHT: 11 lbs.

ACCESSORIES

BOGEII MODEL WMT-l
LINE MATCHING TRANSFORIER

Used for distribution of background music directly from
leased telephone line wired music systems. Provides a per-
fect impedance match between 500/600 ohm balancedline and
high impedance input of amplifier.

This transformer can also be utilized as an output so

cessory for feeding 8 500/600 ohm zero-level sigial for
transmission over a telephone line.

The transformer is housed in a compact metal enclosure
which is conveniently mounted to the amplifier chassis by
two screws. The chassis is pro-drilled for easy mounting.
The WMT-l has a 3-screw terminal strip and a shielded cable
terminated in a phono plug. No wiring or soldering required
for input connections.

INSTALLATION

UNPACKING

Inspect shipping container and unit for indications of im-
proper handling. The unit was carefully checked before leav-
ing factory. If unit has been damaged, make an immediate
claim to dealer or distributor from whom it was purchased. If
unit was shipped to you, notify transportation company with-
out delay and place your claim.

CONN ECTIONS BETWEEN COMPONENTS

Use single conductor, low capacity shielded wire for
connecting the record player, tape recorder, and other COmPO
nents (except speakers) to amplifier. Keep leads under ten
feet in length.

Speakers may be connected with standard flexible line

cord ("zip cord") and up to 100 feet of cable may be used
without appreciable loss.

Make certain that all audio cables are kept from speaker
cables. power cables, and power transformers, and that
speaker cables are kept away from power cables.

GROUNDING THE UNIT

Ground amplifier by attaching a wire from a GNU terminal
on the chassis rear to a good ground such as the metal frame
of the wall outlet or a water or steam pipe.

POWER

Connect the line cord to a walloutlet supplying ll7-volt
AC, 60 cycle power.

INPUT CONNECTIONS

MICROPHONE

Any low impedance microphone (500 ohms or less, 200
ohms nominal) may be used. The microphone should be con-
nected using single conductor shielded audio cable and a
connector, Amphenol type 7$MC1F (or equivalent).

The microphone input circuit includes a builtvin RF filter
coil and shunt capacitor to eliminate RF interference. The
microphone input is extremely sensitive and if the amplifier
is used in the presence of hum fields in a quiet room with a
single speaker the hum pickup may be objectionable. To
avoid this possible hum the RF filter has been jumpered;
however, the jumper should he removed if RF interference oc-
curs. To remove jumper cut red wire across the RF coil at
both sides and remove.

AUXILIARY

A phonograph with a ceramic or crystal type cartridge
may be connected to the AUX receptacle on the amplifier
chassis. Use single conductor shielded cable terminated in a
standard phono plug. It is recommended that a separate
ground wire be connected between the phone player base and
the amplifier GND terminal to minimize hum pickup.

The AUX input may be used for sources other than a
phonograph. Any signal source having a high level, high im-
pedance output may be connected to the AUX input. This in-
cludes virtually all tuners and tape recorders having pream-
plifiers. An input signal level of approximately 0.2 volts is
required to obtain full signal output.

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