Power Amplifier - Eico HF-89 Instruction Manual

MODEL
HF
89
STEREO
DUAL
POWER
AMPLIFIER
general description
GENERAL
The very
finest
techniques
known
to
the
audio
art
are
applied
in
the
HF-89
stereo high fidelity dual
power
am-
plifierto insure the utmost
in
audio
quality
under the most
demanding circumstances.
The
HF-89can
be used with
the
superb
EICO HF85
stereophonic preamplifier or with
any
good self-powered stereo
preamp.
Each power
amplifier of the
HF-89
is
conservatively rated
at
50 watts
and employs the thoroughly
proven cathode-
coupled phase inverter-driven circuit,
preceded by a
direct-coupled voltage amplifier. Ultra linear
connected,
fixed-biased, push-pull EL34's are used
in
the output
stage
and provision
is
madefor
both bias
and dc balance
adjustments.
The very low
impedance characteristic of
silicon
diode
rectifiers
gives the
common
power
supply
for
the two amplifiers
very good
regulation.
As a
result,
signal
conditions
in
one
amplifier
have negligible effect
on the operating conditions of the other amplifier
—
a
very worthwhile feature
in
a high quality design.
To
insure
long
life for
the silicon
diode
rectifiers,
electro-
lytics,
and
tubes,
asurgistor
is
included to limit the start-
ing surge currents.
SPECIFICATIONS
Output Power;
100 watts (two
50watt
amplifiers) contin-
uous,
200 watts
peak
IM
Distortion (60
&
7000
CPS
at 4;
1);
0.
5%
at
100 watts
Harmonic
Distortion: Less
than
0.
25%
from
30
to
1
5,
000
cps
and
less
than
1%
from
20
to
20,
000 cps within
Idbof
1
00 watts
Frequency
Response: ±0.
5db 5
cps -
lOOkc
Rise
Time:
2.
5usec
Square-Wave
Response:
Essentially undistorted to 20,
000
cps
Inverse
Feedback:
18db
Stability
Margin: 13 db
Damping
Factor:
above
12,
20
cps to
20kc
The
intrinsic
quality of the driving
circuit, the output
tubes,
and the output transformers
in
the
HF-89
is
unsur-
passed.
IM
distortion at
normal
listening levels drops
to
below
0.
1%, and even
at 100,
000 cps
a
total
of
60
watts
undistorted output
is
available
to insure
unimpaired
tran-
sient (square
wave)
response
even
at
very
high
power
levels.
The low end
is
extremely
solid
and
full,
as
an
undistorted
total
power
output of
78
watts
at
15 cps
and
28 watts
at
10
cps
would
imply.
Furthermore, the high
circuit
and component
quality
results in less
feedback
required
to
achieve
these
very low
distortion figures, so
that the
HF-89
amplifiers
have a very healthy
stability
margin
to insure
perfect
results in
any
application.
The methods of stereo recording are such
that, at
moments,
practically
all
the sound
is
in
one
channel or the
other.
For
this
reason, the best stereo
installations require
an
amplifier
in
each channel
as
powerful
as that
used
in
the
best
monophonic
installations.
50 watt
amplifiers
have
been found very worthwhile
in
the best
monophonic
instal-
lations
and
actual
50watt amplifier will
be found
equally
worthwhile
in
the best stereo installations.
Channel Separation:
60db
Sensitivity:
0.
55V
for full
output
Hum:
Better
than
90db below
full
output
Controls:
Level Ch.
1,
Level Ch.
2,
"Service Selector"
switch,
ON-OFF
switch
Speaker Connections:
4,
8,
and 16
ohms
Tubes:
1-ECC83/12AX7, 2-6SN7GTB, 4-EL34,
2silicon
diode
rectifiers
(power),
1
selenium
rectifier
(bias);
sur-
gistor
protected
for
long
life
Pbwer
Source:
1 1
7V,
60
cps
Power Consumption: 215watts
at
no
signal,
270
watts at
1
00
watts out
Size;
15"
x
11"
x
6"
Shipping Weight: 37
1/2
lbs.
1
COPYRIGHT©
1960 ELECTRONIC INSTRUMENT
COMPANY,
Inc.