Eico HF-20 - Product Description; Preamplifier-Equalizer Circuit; Power Amplifier; Installation Guide

MODEL
HF20
HIGH
FIDELITY AMPLIFIER
The EICO
Model
20
ts
the
result
of
o program
aimed at
bringing
together In one
Integrated unit the finest pre-
amplifier
control,
and power amplifier circuitry.
Please
read
the following Instructions
before Installing
or
using
the
amplifier,
particularly
If
you
are not
thoroughly
fa-
miliar
with
equipment
of
this type. You will
learn how
to
Install the amplifier
properly
and
how the
controls
and
facilities
should be used to obtain
the
best
results.
You
may
skip over the
Installation
section
If your
ampli-
fier
Is
Installed by a
competent
technician,
but
this
section contains
important
specific
Instructions and a
mounting template
which should
bemode
available
to the
person
performing
the
Installation.
In
anycase.
It
ts Im-
portant
that
this
manual
be retained
since
It
contains
es-
sential
servicing
Information
which will
be
needed
by
any
person
who
undertakes
to
service the
amplifier.
DESCRIPTION
The
Model 20cons!stsofa
high
quality
preamp-equal
lzer
and
control section plus a
20 watt
Ultra-LinearWilliam-
son
type
power
amplifier.
Details are as
follows:
THE
PREAMPLIFIER-EQUALIZER
CIRCUIT possesses
ex-
tremely low distortion
due to equalization entirely
by
feedback-”!!
was chosen
deliberately because
of Its
ability
to
match the low-dlstortton
performance
of
the
Ultra-Lin-
ear Wllllamson-type amplifier
circuit* It
has
a balanced
selection
of equalizationswhich, together
with the wide-
range bass and
treble tone controls,
permits
correctcom-
pensatlon for practical
ly
any mtcrogroove or 78 recording
characteristic, foreign
or
domestic.
FOUR
HIGH
LEVEL
INPUTS AND 2
LOW-LEVEL
INPUTS
(1
switch
position)
enable
the
*20
to accommodate
TV,
tape recorder,
AM-FM tuner,
and crystal cartridge (or
separate
AM
and
FM tuners),
as
well
as
any
leading mag-
netic or FM pickup without
the necessity of
component
changes.
A low
Impedance,
logically-placed tape
out-
put
[ack
ts
a
valuable
convenience for
those
owning
or
planning
to own a tape recorder.
THE
BASS AND TREBLE
TONE
CONTROLS
are
of
the new
feedback
type
for
exceptionally
low distortion and wide
frequency range.
Theydo
not
affect
the volume or Inter-
act with
each
other—
providing
the
easiest
possible con-
trol
settings.
As turnover
on both
ends varies with
the
amount
of boost and
attenuation,
boost or cut at
the ex-
tremes of the audio range
Is possible without affecting
the
mid-range.
THE
LOUDNESS
.CONTROL,
a
Centralab
Compentrol,
raises or
lowers volume
In
strict
accordance
with
the ac-
cepted
Fletcher-Munson
ear-response curve.
Operation
together
with
front
panel
level control
provided
Is
widely
heldas
oneof the most
flexible and
sensible arrangements.
THE POWER
AMPLIFIER:
The power
amplifier In the
*20
is
of
the
Ultra-Linear
Williamson
type.
Its
superb
perform-
ance characteristics
are
augmented by
the
high-quality
output
transformer,
which
Is
conservatively
rated
at
25
watts.
SPECIFICATIONS
Power Output:
20
watts
(34
watts peak)
IM
Distortion
(60 &
6000
cps/4:
1,
20
W)
:
1. 3%
Mid-Band Harmonic Distortion
(20W):
0.3%
Power
Response
(20W)
+0,
*1
db 20
to
20,000cps
+0,
“3
db 10
to
40,000
cps
Frequency
Response
(1/4W)
:
+0,-1
db 13*35,000
cps
+0,
“3
db
7"50,000cps
Damping
Factor
:
7:1
Inverse
Feedback:
14 db
Speaker
Connection Taos
:
4,
8,
and
16
ohms
Tone Controls:
Bass:
15db boost or cut at
50cp?
Treble: 1
5 db boost or cut
at
lOkc
Phono Equalizations
: RIAA, Columbia,
London, Euro-
pean
78,
American 78.
Sensitivity
:
Mag. Phono
0. 004 V rms
(atl
kc)
for
20W
output
Tuner,
etc.—
-0*4 V
rms
for
20W
output
*
Hum
&
Noise: Mag. Phono**
—
60 db
below 20W
Tuner, etc.
__75db below
20W
**
Includes 16 db
boost
at
60 cps due
to
RIAA
compensation.
*
Maximum
gain
and
tone
controls
set
at
flat positions.
«
i
Power
Une Requirement
1Q5~125
volts,
50/60 cm AC
only
Power
Consumption
s 1 00 watts
Size;
8
1/2"
high,
15"
wide,
10"
deep
Weights 24
lbs.
INSTALLATION
1
.
GENERAL FACTORS
a)
HEAT
DISSIPATION
(VENTILATION):
In
common
with
other electronic equipment,
the
Model
20
produces
a
great
deal
of heat
in
normal
operation.
Unless
contin-
uous
and
adequate air flow ts
obtained
around
the
heat
producing
elements, these
elements will
over-heatand
their useful
life will be
greatly
curtailed.