Fisher 80 AZ Service Manual

Page 1

THIE IF! ~~ HER

3. Wmw
AUDIO AMPLIFIER

INSTALLATION AND

OPERATING

INSTRUCTIONS

MODEL 80-AZ

$1.00

PRICE

NEW YORK

FISHER RADIO CORPORATION

Page 2

THE

lFIS HER

3. eWa/H

AUDIO AMPLIFIER

MODEL

GENERAL INFORMATION

THE FISHER Audio Amplifier, Model 80-AZ,
will meet the requirements of the most exacting
user. Complete fidelity of reproduction and ab-
sence of listener fatigue are a direct result of
the extremely low harmonic and intermodulation
distortion at all power levels, as well as excellent
transient response, wide frequency range and
good linearity. Hum and noise are virtually non-
measurable, thus allowing operation at all listen-
ing levels without the distraction of extraneous
noise. The great reserve power handling capacity
of the Model 80-AZ makes it capable of repro-
ducing the complete dynamic range even of a
full symphony orchestra. All components in this
compact unit have been selected for long life
and installed with maximum accessibility in
mind, for easy servicing.

The Model 80-AZ has three separate feedback
loops, resulting in low internal impedance, ex-
tremely low distortion and excellent transient
response. Two type EL-37 tubes, connected as
tetrodes, are employed in the power stage. The
unique cathode feedback Circuit oflers all
the advantages of triode performance, together
with efficiency of tetrodes. The carefully designed
output transformer consists of fifteen interleaved
windings in conjunction with a grain-oriented
. steel core, assuring the finest results.

80-AZ

THE FISHER Model 80-AZ may be used di-
rectly with an FM-AM tuner, such as THE
FISHER Mod_el8&L a crystal phonograph
cartridge or any other device which is capable
of producing a one-volt signal. Where magnetic
phonograph cartridges, microphones or similar
low-level devices are employed, pre-amplification
is necessary. Especially suited to these latter
applications is THE FISHER Master Audio
Control, Series 80-C, available as a companion

unit to THE FISHER Model 80-AZ.

SPECIFICATIONS

HIGH OUTPUT, with less than V2% distortion
at 30 watts (less than 0.15% at 25 watts; less
than 0.05% at 10 watts.)

INTERMODULATION DISTORTION less than V2% at
25 watts and less than 0.2% at 10 watts; see
FIGURE 1.

FREQUENCY RESPONSE is uniform Within 0.1 db
from 20-20,000 cycles and is within 1 db from
10-50,000 cycles; see FIGURE 2.

POWER OUTPUT is constant within 1 db°at 30
watts from l5-35,000 cycles; see FIGURE 3.

HUM AND NOISE level is better than 95 db below
full output.