Older Heathkit Gear--Hi Fi Stuff

[Keith Rowland]

Bonus Follow-On to Older
                  Heathkit Test Gear, Previously Transmitted

W-4 and W-4M     Hi-Fi Amplifier.  Williamson circuit, single-chassis
(power supply and amp on one chassis).  Has the new Chicago Transformer
Co. Model BO-13 "super-range" output transformer.  This transformer, a
new development in the hi-fi field, is offered at substantial savings
over transformers of comparable quality.  Equal in every respect to
transformers used in Heath W-2 and W-3 series.  Rig has heavy duty power
transformer and choke.  All features of previous models, including
individual jacks and a wire-wound control to balance the output tubes.
Plastic hi-quality caps and exact circuitry previously used in
Williamson type amps.  IMD (Intermodulation Distortion) both at same
levels as W-2 and W-3 models.  W-4M with Chicago "super-range
transformer only $39.75.  W-4 with Chicago "super-range" transformer and
WA-P2 preamplifier, 35 lbs., 1955 price:  $59.50.

W-3     Hi-Fi Amplifier.  Uses Williamson circuit with Acrosound TO-300
output transformer, using the popular "ultra-linear" output circuit for
clean maximum power level.  Separate chassis for amp and power supply.
Frequency response:  Flat within 1db from 10 Hz to 100,000 Hz.
Haromonic distortion @ 5-w output less than 0.3% from 20 Hz to 20 kHz.
IMD @ 5-w equivalent output, 0.5% using 60 and 3000 Hz test
frequencies.  Output impedances:  4, 8 or 16-ohms. Main amp, power
supply and WA-P2 preamp, 37 lbs.  1955:  $69.50.  Dimensions:  H7" X W5
1/2" X L11 1/2".  W-3 (no preamp), 29 lbs., 1955 price:  $49.75.

A-9B     20-w Hi-Fi Amp.  Improvement on an unstated previous amp.
Heavier power transformer and new output transformer.  Output
impedances:  4, 8, 16 and 500-ohms.  Harmonic distortion will not exceed
1% at rated output.  Frequency response plus or minus 1db 20 Hz to 20
kHz.  Separate boost and cut bass and treble boost controls.  Proper
equalization for all input devices provided.  Tubes:  12AX7magnetic
pickup preamp and 1st audio, 12AU7 2-stage amp with tone controls, 12AU7
voltage amp/phase-splitter, 2-6L6 output amps, 5U4 rectifier.  24#.
1955:  $35.50.

A-7B     Ad headline says 6-w amp.  Blurb in ad says 5-w amp.  Has two
switch-selected inputs for crystal and ceramic phono pickups, tuner, TV
audio, tape recorder and carbon mike.  Separate bass and treble
controls, push-pull balanced output.  Output impedances:  4, 8 and
15-ohms.  Frequency range:  Plus or minus 1.5db 20 Hz to 20 kHz.  A-7B,
10 lbs.  1955 price:  $15.50.  A-7C includes pream and compensation for
variable reluctance cartridges and low-level mikes:  $17.50.

WA-P2     Hi-Fi Preamplifier.  Can use for remote control of power amp.
Has compensation for fono pickups of various types.  Five separate
switch-selected input channels, two low level and three high level, each
with its own input control.  Full record equalization with four-position
turnover control and four-position rolloff control.  Output jack for
tape recorder.  Separate bass boost control with 18db boost and 12db cut
@ 50 Hz.  Treble control gives 15db boost, 20db cut @ 15 kHz.  Special
hum control.  Overall frequency response flat within 1db 25 Hz to 20
kHz.  Satin-gold finish.  Tubes:  2-12AX7, 1-12AU7.  Requires 6.30-v @ 1
A. and 300-v @ 10 ma.  7 lbs.  1956:  $19.75.

A7-D     7-w Amp.  Basically a slsight improvement on the A-7C.  10#.
1956:  $16.95.

BC-1     Broadband AM Tuner.  Low-distortion detector, broadband IF.
Voltage-douobler detector employs crystal diodes for low distortion.
Excellent sensitivity and selectivity.  Audio response:  Plus or minus
1db 20 Hz-2 kHz with 5db preemphasis @ 10 kHz to compensate for station
roll-off.  Covers 550 kHz to 1600 kHz.  Has 10 kHz whistle filter.  6db
S/N ratio @ 2.5 microvolts.  RF and IF coils pre-aligned.  Built-in
power supply.  AVC.  2 outputs and 2 antenna inputs.  8 lbs.  1957:
$25.95.  (I still have the one I built in 1957, and it's amazing how
good it sounds even now!)

XO-1     Electronic Crossover.  Separate lows and highs for feed to
separate amplifiers and speakers, eliminating the need for conventional
crossover circuits.  Does the job electronically.  Crossover
frequencies:  100, 200, 400, 1200, 2000 and 3500 Hz, selectable with
front panel controls.  Separate level control for each channel.
Minimizes IMD problems/  Handles unlimited power, since frequency
division is accomplished ahead of the power stage.  Attenuator is
12db/octave, with sharp knee @ cutoff frequency.  6 lbs.  1957:  $18.95.

W-4AM     20-w Amp.  Williamson circuit.  5881 PA tubes.
Chicago-Standard Transformer.  Response:  Plus or minus 1db 10 Hz-100
kHz @ 1-w.  Harmonic distortion 1.5%; IMD below 2.7% @ full output.
Hum/noise 95db below full output.  Output transformer taps for 4, 8,
16-ohms.  28 lbs.  1958:  $39.75.

W-5M     25-w Amp.  Peerless Company transformer and KT66 tubes in
output.  25-w but will follow instantaneous peaks of full orchestra to
42-w.  Tweeter-saver suppresses high frequency  oscillations.  New type
balancing control facilitates adjustment of dunamic balance of output
tubes.  Flat plus or minus 1db 5Hz-160kHz @ 1-w.  Within 2db 20Hz-20kHz
@ full output.  THD)Total Harmonic Distortion) less than 1% @ 20-w.
(using 60 & 1000Hz 4:1 tones). Hum/noise 99db below 25-w output.  Black
and gold cabinet.  30 lbs.  1958:  $59.75.

W-7M     55-w Amp.  55-w 20Hz-20kHz with less than 2% THD throughout the
range.  Paired output connections allow instant switch selection of
"unity" or "maximum" damping factors for all 4, 8, or 16-ohm speakers.
Each output has optimized current feedback circuit for unity damping so
that there is no compromise at any impedance used.  The current feedback
circuitry is entirely shorted out when not in use to obtain the highest
possible damping factor.  Features include level control and on-off
switch right on the chassis, plus provision for remote control from
preamp, etc.  Balance control for EL-34 output tubes.  These tubes
operate into a high-quality tapped-screen transformer designed for this
unit.  A 70-v input on the transformer (surely they meant to say
"output" in the ad) provides for P.A. or large music systems.  Silicon
diode power supply features a protective device that controls current
until tubes warm up.  Black and gold case is 6"H X 8 1/2" D X 15"W.
Pilot light on chassis.  28 lbs.  1958:  $54.95.

W-6M     70-w Hi Fi Amp.  Silicon diode rectifiers.  Variable damping
control.  4, 8 or 16-ohm or 70-v output.  Frequency response 5Hz-80kHz @
1-w. with controlled high frequency rolloff above 100kHz. THD @ 70-w
below 2% from 20-20,000Hz.  Hum/noise 88db below full output.  52 lbs.
1958:  $109.95.

Th-th-that's all, folks!

73, Keith

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