Eico HF 85 Owners Manual

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MODEL HF- 85

STEREOPHON lC PREAM PU HER

general description

GENERAL

The EICO Model HF-85 is a complete high fidelity ster-
aaphonic control center. It offers practicallyevery con~
trol and switching facilityanyone could want in a physi-
cal design adaptable to any type of installation. With it
you can select, preampllfy and control accurately, any
stereophonlc source, whether it be from tape, discs or
broadcasts. Every control facility is both useful and of-
fectlve.

Extremely low distortion, bordering on the immeasurable
(even at high output levels), precludes any degradation
of quality from the best modern program sources.

The HF-85 is self-powered, utilizing a fullewave rectifier
tube power supply. it works in coniunction with any two
high quality power amplifiers, such as the ElCO HF-l4,
HF-ZZ, HF-SO, HF-35, HF-50, and HF-60.

FEATURES

1. Separate low level input in each channel for mag.
phone, tape head, and microphone. Circuitry carefully
designed to provide the high gain required by tape heads
and high quality, low output mag. cartridges without hum
and noise problems. A front panel switch permits choice
of the proper NARTB tape head equalization for either
7 1/2 8. l5 or 3 3/4ips tape speeds.

2. Separate high level inputs for AM tuner, FM tuner,
and FM Muitiplex. Also two auxiliary A inputs (one in
each channel) and two auxiliary B inputs (one in each
channel). Input selector switch on front panel has posi-
tions forfeeding FM tuner output to one channel and AM
tuner to the other, or FM tuner to one channel and FM
Multiplex adapter output to the other.

3. independent level controls that may be operated sapm
arately or together with a built-in clutch.

4. Distortionless, 3-stage, independent bass and treble

tone control circuits in each channel. Each tone control
circuit consists of a feedback amplifier pair (30 db of feed-
back) driving a true variable crossover, feedback tone
control stage. Bass and treble controls do not interact
with each other or affect the level. Bass controls in both
channels and treble controls in both channels are concen-
tric. Controls may be operated individually or together
with a built-in clutch.

5. Fletcher-Manson loudness compensation for low level
listening which may be disabled by front panel slide switch.

6. Extremely versatile function selector permits listening-
to each channel separatelyfor checking purposes; on stereo
listeninglto reverse the channel connections; on mono-
phonic record playing with a stereo cartridge,to mix the _
two channels forcancellation of vertical rumble; on mane
ophonic tuner,to have the channels unmixed so as not to,
introduce extraneous noise from the unused input.

7. Low impedance output to tape recorder, useful on all
inputs. Output to main amplifier impedance permits use
of up to 40ft. of 25mmfcl/ft. shielded audio cable before
response at 20, 00°C is affected.

8. Hum balance control, pilot lamp, convenience out-
lets.

9. New " low-silhouette" construction matches ElCO
tuner. Very attractive when placed on a shelf or out in
the open, yet permits easy console installation with full
shielding and adaptability to any panel thickness. in-
ploys one piece horizontal chassis(cadmium plated steel)
attached to the centers of two side pieces (brown enamel ed
steel). Unit is self-supporting For easy servicing top or
bottom. Perforated steel cover (metallic-gold painted)
slides in and out on rails in the side places. A bottom
plate and front bezel (both brown enameled stee|)plus a
solid brushed brass control plate complete the assembly.
Controls may be usedas either concentric or ganged with
built-in clutch mechanisms.

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Fee

1

SPECIFICATIONS

Fre uanc Res me: i0. 3:: 5-200,000c at any level
up to 5% RMS out. (Measured from high level In-
put: with level controls set at maximum and tone
Controls electrlcally Flat.)

Sensitivity (Input For 2V RMS eutput at 1000 cps: Mag.
Phone-I mv; Microphone-I mv; Tape-Head -0. 5
mv; ngh Level Inputs -0. 17V.

Hum 8. Noise: Mug. Phono-éOdb; Microphone-60%;
Tape l-lead -50db; High level inputs - 75db. (For
low level Inputs, values given are equivalent
noise Input in db down from IDmv input level.
For high level inputs, value given is equivalent
noise input in db down from 0. 5V input level.)

lm Distortion 60 and 70000 at 4 : I):

[M DIS . OUT
0.67% 0.5V
0.03% 1.0V
0.04% 2.0V
0.07% 3.0V
0.11% 4.0V
0.17% 5.0V

Harmonlc Distortion (20-20, 000:: ): 0.1% at 3V RMS
out; 0. iii at 3V WS 001.

Tone Control Run a: At IOkc: i5db boost, l5db cut; at
35cm: 15'35 boost, lSdb cut.

E uelizution: Phone -RIAA; Tape Heud- NARTBfor ISIps
0:13 7 I/2ips, 3 3/4ips.

Output to Tape Recorder ImEdance: I, 400 ohms.

Output to Main Amellfier Impedance: 8, 000 ohms.
Tubes: 5* IZAX7/ECC83, I- 6X4

Size: 3 5/ " high, 12" wide, 8 1/2" deep.

Weight: 9 1/2 lbs.

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[

tuner input connector to the appropriate input iack on
the preamplifier and with the tunerset in between stations
and the tuner volume control set at minimum, find the
prong position of the tuner line card in one of the con-
venience receptacles on the basic power amplifiers that
gives the least hum. Finally, connect the phone input
connectors to the PHONO CH. l and CH. 2 inputs (stereo
mag. cartridge), or through the recommended adaptors to

operation

these inputs (stereo ceramic cartridge), or to one set of
auxiliary A or B inputs (stereo crystal cartridge)ond do
the some with the power plug of the turntable (turntable
off and pickup arm at rest position) using the ii7VAC
convenience receptacle on the preamplifier. When all
of this is completed, adiust the hum balance control on
top of the preamplifier chassis for least hum.

PRELIMINARY: Be sure all tubes are firmlyseated in their
sockets and that the tubeshields are making good contact
with their bases. As initial adiustments, set these controls
as follows: LEVEL controls 1 & 2 at 0, BASS controls l 81
2 at O, TREBLE controls 1 8- 2 at 0, LOUDNESS compen-
sation switch at OFF. Turn the system on by setting the
POWEstit-ch at ON. Please note that in the instructions
that follow, it is assumed that a stereo pickup and/or a
stereo tape head is being employed in the system.

LEVEL, BASS, & TREBLE controls: The LEVEL, BASS, and
TREBLE controls each consist of two concentrically mount-
ed controls, one in each channel. A built-in clutching
device is effective when the smaller diameter inner knob
(Amplifier 2 control) is pressed in against the larger di-
ameterouter knob (Amplifier 1 control). At the in (clutched)
position, taming either knobwlll cause both knobs to turn
together, to make the same odiustmenmboth channels
simultaneously. The clutching deviceis disengaged when
the smaller inner knob is pulled out, making it possible to
turn and adjust eochof the controls independently. Please
note that the clutching mechanism is designed to permit
slipping, so that either the inner or outer control can al-
ways be turned to either minimum or maximum even if the
other control is engaged to it in a more advanced position
in the desired direction of turning. The optional clutching
arrangement iust described in intended to be used in the
following manner: to adiust level balance, baa balance,
and treble balance between the two channels (to income-
date the inevitable gain differences between channels due
to tolerances and aging of components, loudspeaker re-
sponse differences, roam acoustics), the controls are dis-
engaged for independent adlustment; once balance has
been achieved, the controls are engaged to permit sim-
ultaneous adjustments of level, bass and treble in both
channels for different records, program material, and de-
sires os to listening level.

SELECTOR Switch: The SELECTOR switch selects cone-
spending pairs of inputs to both channels. The program
source being fed to any of these pails of inputs may be
either stereophonic or monophonic. The MODE switch
takes care of setting up the preamplifier according to the
type of the program source (stereophonic or monophonic,
tuner or phone, etc.) and also performs other functions
detailed in the description of the MODE switch. The
AUX A, AUX B, AM-FM and FM-MULTi are all high

leVEl pairs of inputs suitable for stereophonic or "lano-
phonic crystai cartridges, AMor FM tuners, AM-FM stereo,
FM-FM Multiplex stereo, pre-amplified equalized tape
playback, tv sound, etc. As to monophonic tuner, use
the AM-FM position for AM tuner selection, and FM-
MULTI for FM tuner selection. When independent AM
and FM tuners are used, and/or on FM Multiplex adaptor
is used in conlunctian with or is incorporated in the FM
tuner, the some two positions can be used for AM-FM or
FM-FM Multiplex stereo broadcmt selection. The MIC,
PHONO, and TAPE positions of the SELECTOR switch on
all low level pairs of inputs; the MlC pair provide straight
amplification for microphones, the FHONO pair RlAA
standard equalization and amplification suitable for mag-
netic cartridges or ceramic cartridges with appropriate
adaptors, the TAPE pair NARTB tape equalization and
amplification for tape heads.

TAPE Switch: Adlusts the equalization at theTAPE (head)
positionof the SELECTOstitch according to the NARTB
standard for the 7 1/2 (8. l5) ips tape speeds and the 3 3/4
ips tape speed.

MODE Switch: The STEREO NORMAL and STEREO RE-
VERSE positions are both used for stereophonic reproduc-
tion. At the STEREO REVERSE position, the channel 1
and channel 2 amplifiers from the tone controls to the
amplifier connections are interchanged. These two posi-
tions permit interchanging thesignals fed to the two speaker
so that the correct left to right display of the orchestra
can be achieved on all recordings or broadcasts. The
CHECK AMPL. l and CHECK AMPL. 2 positions permit
hearing either channel 1 alone or channel 2 alone for
comparison orbalancing purposes during stereophonic use.
The MONOPHONIC TUNER, AUX position is used for
monophonic FM, AM, tv sound, monophonic phone cart-
tidge,mcnophonicpro-amplified tape etc., fed Into chan-
nel 1 inputs. At this position, the channel 2inpuls which
are unused in this type of operation, are disconnected
from the active channel so that they cannot contribute
interference. At the MONOPHONIC PHONO position,
the channel l and 2corresponding inputs are mixed, which
is useful when playing monophonic rocordswith a stereo-
phOnic cartridge to cancel vertical rumble components.
The internal arrangements of the HF-85 at each of the
positions of the MODE switch are shown in Fig. 2.