Building Better Tube Amps With Heathkit Parts

[Justin] had been trying to find a good tube amp for years, but all the best examples were either expensive or a complete basket case. Instead of buying a vintage stereo tube amp, he decided to build his own using the guts of a Heathkit AA-100, a popular tube amp from the 60s and 70s that doesn’t have a great reputation for sound quality.

This project was based on an earlier project from a decade ago that replicated the very popular Dynaco ST-70 tube amp from parts taken from the Heathkit AA-100. The schematic for this conversion was readily available on the usual tube head message boards, and a few PCBs were available for the input stage.

With the schematic in hand, the next thing for [Justin] to do was get a nice enclosure. High quality tube amps are valued as much for their appearance as they are for their sound quality, and after giving his father-in-law a few sketches, a cherry hardwood chassis stained in a beautiful golden brown appeared on [Justin]’s workbench.

The big iron for this new tube amp was taken directly from the old Heathkit, and a few hours in front of a mill netted [Justin] a chassis panel drilled out for the transformers and tube sockets. The rest of the project was a bit of assembly, point-to-point wiring, and wire management giving [Justin] a fantastic amplifier that will last for another fifty years until someone decides to reuse the transformers.

13 thoughts on “Building Better Tube Amps With Heathkit Parts

  1. what a great photo-rich write-up! love how there is such a wealth of images and you can get an idea of what went on just by 1 minute of scrolling.

    that’s how to do it. cheers, man!

  2. can you have shoddily cheap tubes where they work but are bad quality signal or instead of the full 29 to 30 inches of vacuum done by a vacuum pump they use their mouth and suck a only a couple inches or omitted the mercury or even used burned out or failing tubes pulled from junk units?

  3. My Opinion:

    1. Subjectively > Nice work from an Aesthetic “Old-Tech” point of view! I like the physical build.

    2. Objectively > What a complete waste of time: Do a modern analog or hybrid-digital “Chip-Amp” solution instead.

    1. I am not in the audiophile elite, but there is a ‘sound’ to to vintage equipment, especially if you pair the equipment appropriately – eg a nice tube amp with very efficient reflex or horn-loaded speakers. Not saying it’s higher fidelity or better than today’s stuff, but it is enjoyable, and flattering to some music, especially acoustic jazz. And it looks so cool…

      Nice build! Now you need some Altec A-7s…

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