Eico HF 86 Owners Manual

Page 2

mom Hi- 86 STEREO DUAL POWER AMPLIFIER

general description

GENERAL

The HFBéis a dual poweramplifiertor stereo usewith the
superb HF85 stereo preamp or any gaocl stereo preamp
that is self-powered. Each power amplifier is conserva-
tively rated at 14watts outputcnd employs aWilliamson-
type circuit witha push-pull EL84-outputstage. The two
amplifiers maybe operated in parallel to deliver 28watts
for non-stereo use; either input can be made common for
both amplifiers by a service selector switch. Other con-
venience features include a level control at eachinput,
an a-c power switch, two convenience outlets, and a
Fuse in an extractor post mounting.

The design and construction of the HF86 clearly shows
the value of ElCOs experience and continuous develop-
mentwork. Probablythe mostinteresting innovation is a
new tube type, the 12DW7, developed at EiCO's request
and appearing For the first time in this amplifier. This
newtube is a medium-mu trlode of the 12AX7 type anda
low-mu triode of the 12AU7 type in a single envelope
with coiled heater onstruction; this type is controlled
in production for audio use. The IZDW7 conveniently
provides significantly better performance characteristics

SPECIFICATIONS

Output Power: 28 watts (two 14wattamplifiers) contin-
uous, 56 watts peak

[M Distortion (60 & 7000 c s at 4:1): 1. 5% at 28 watts
(m. eachl, 0.5% at 0 watts l5? each), 0.3% at 4

watts (2w. each)

Harmonic Distortion: 16 watts (8w. each) less than 1%
From 30c to lSkc; 20watts (10w. each) less than 1% From
40c to 15kc; 28watts (14w. each) less than 2% from40c
to l5kc and 1% from 50c to 7kc; 20c distortion; 3% at
12. 5 watts (6. 25w. each)

Fro uenc Response: 2watts (1w. each) i=0.5db 10: to
10&c

Transient Response: Excellent square wave reproduction

l4 usec rise timal; negligible ringing, rapid setting on
10kc square wave

Inverse Feedback: 20db

in the familiarvoltage amplifier andspiit-load phase in-
verter of the Williamson-type circuit. The 12DW7 will
also be available directly from EiCO. Other important
design Features, characteristic at all EICO amplifiers,
are a rugged and generous chassis, maximum separation
at power tubes from each otherand heat-sensitive compo-
nents, trouble-free point-to-point wiring, and painstaking
attention to reducing distortion without compromising
stability. Filter electrolytics and rectifier: operate well
below maximum ratings to insure long life.

The HF-86 has been designed to maintain its excellent
characteristics under speaker load (including electro-
static types) as well as the resistive load normally used
for testing. Phase corrections have been provided at both
extremes of the audio spectrum to insure stability under
all conceivable conditions and to insure that variations
in components and construction wllinotatfect the perfor-
mance. Stability is maintained on all speaker tops with
loads ranging From zero to infinity. Overload character-
istics are excellent and the HF-86 will not esdtibit bounce
or flutter under pulsed conditions.

Stability Margin: 15db
Sensitivity: 1. 15V for 14w output

Hum: 90db below rated output

Speaker Connections: 4, 8, 16, and 32 ohms

Controls: Level Ch. 1, Level Ch. 2, Service Selector"
switch, ON-OFF switch

Tubes: 2-12DW7, 4-ELB4, 2-5281

Power Source: 117V, 60:

Power Consumption: 115 watts
Size: HWD - 5" x 13 1/ " x 9

Shipping Weight: 16 lbs.