Heathkit A5C
Very little is documented about the Heathkit A5C. What exists comes from a single collector source, and it is thin on dates and pricing. The A5C was a mono-block pair of tube amplifiers - two separate chassis, one for each channel - designed specifically for home use. In its day, it was the top-of-the-line amplifier from Heathkit.
The circuit is essentially the same as the famous A9 used in movie theaters. Each amplifier is conservatively rated at 10 watts into 16 ohms, or 12 watts into 8 ohms. The output stage uses a pair of 6L6G tubes per channel, with two 6J7 input tubes and a 5U4G rectifier. The power supply is separate and choke-filtered, and the A5C uses two 0A3 regulator tubes to stabilize the voltage. The restorer of the surviving unit added a balance pot when replacing the original capacitors.
These are Class A/B 6L6G amplifiers with RCA/phono jacks for input. A surviving example had its old "death caps" removed, new capacitors installed in the power supplies, a proper three-wire cord fitted, and new tubes throughout. That is routine work for a tube amp of this era. A period ad in Audiocraft (April 1957, p.15) touted Heathkit's dual-chassis hi-fi amplifier kit featuring the Acrosound TO-300 output transformer and 5881 tubes.
Beyond that, the record is genuinely thin. No production years, original price, dimensions, or frequency response data have surfaced. It's a handsome, well-regarded piece of early Heathkit history — just one with very little paperwork attached to it.
- Type: Mono-block pair of tube amplifiers, home use
- Output: 10W into 16 ohms; 12W into 8 ohms
- Tubes: 2× 6L6G output, 2× 6J7 input, 5U4G rectifier, 2× 0A3 regulators in power supply
- Construction: Separate power supply / choke
- Inputs: RCA/phono jacks
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