Vintage Heathkit AA-21 Series B transistor stereo integrated amplifier from the early solid-state hi-fi era.
The AA-21 is more than a simple power amplifier: it combines the preamplifier/control section and stereo power amplification in one chassis. Its early transistor circuitry, distinctive hinged lower control panel, period Heathkit styling and extensive source/speaker connections make it an interesting restoration project as well as a collectible piece of 1960s hi-fi history.
PERIOD AA-21 SPECIFICATIONS / FEATURES:
• Heath rating: 35 watts per channel into 8 ohms — 70 watts total
• IHFM music-power rating: 50 watts per channel into 8 ohms
• Power response: 13 Hz to 25 kHz ±1 dB at rated output
• 28-transistor / 10-diode design in period AA-21 literature
• Inputs for tape head, magnetic phono, tuner, stereo tuner, tape monitor and auxiliary sources
• Speaker connections for 4, 8 and 16 ohm loads
• Hinged lower front panel conceals secondary controls including tape monitor, speaker phase reversal, loudness and input-level controls
• Early all-transistor / solid-state Heathkit design
TESTING / CONDITION:
• Unit powers on.
• The left channel produced audio during our basic test. It sounded generally good, although not perfectly clear.
• No audio was obtained from the right channel during our test.
• All four panel lights are inoperative and do not illuminate.
• No further troubleshooting, diagnosis or electronic service was performed.
• We do not know whether the right-channel problem is caused by a control/contact issue, amplifier circuitry or another fault.
• Because of the right-channel fault and lighting issues, this unit is being sold for parts, repair or restoration and not as a fully working amplifier.
• Externally it appears substantially complete. Vintage cosmetic wear, scuffs/soiling and edge wear are present. Please examine all photos carefully.
PERIOD PROVENANCE:
Handwritten inside the cover is:
Glen E. Rudisill
March 15, 1964
Total Price $139.42
We cannot verify who wrote this notation or state with certainty that it identifies the original builder, but it appears to be period ownership/build information and is an interesting part of this amplifier's history.
Period advertising from 1964 placed the Heathkit AA-21 kit at approximately $139.42.
INCLUDED:
Heathkit AA-21 Series B amplifier as pictured. No manuals, speakers or other accessories are included unless specifically shown in the photographs.
The technical specifications above are provided from period AA-21 reference literature as model information. They are not a claim that this unrestored amplifier currently meets original factory specifications.
A strong candidate for a Heathkit collector, early solid-state audio collection, vintage hi-fi restoration or parts donor.