Chose You Path

Showing posts with label tube amp. Show all posts
Showing posts with label tube amp. Show all posts

Tuesday, June 10, 2025

Heathkit AA-32- Archeology

 




The Heathkit AA-32





Good ol' Ebay

About 20 years ago I bought a sealed Heathkit AA-23 for about $200 and stuck it in a closet.  I felt an affinity to it because at that time I was working in a building Benton Harbor, MI that some of the Heathkit operations had used.  The last copyright date on the materials I could find was 1969.

Huge respect for people back then that could assemble this as a beginner with limited experience.  Society must have been better and more practical back in the day.


When I opened it everything looked brand new.
I replaced the electrolytic caps with modern equivalents.

The tubes are what you would expect from a 1960's budget kit amp, 6EU7s and the venerable 6GW8/ECL86 combo output tube.

The next pictures show the buid-up of the parts.  I have been building things for quite a while and this thing was a challenge. Part of it was the 34 page step by step instructions with non-intuitive 

"Connect a 4-1/2" wire from lug 1 of terminal strip D (S-3) to lug 1 of terminal strip E (S-2)" 

Looking up pictures of which terminal strip/lugs etc was headache inducing.  Ended up with just using the pictures and the schematic.





I uprated the voltage doubler from the supplied 30uf caps to 200uf caps and UF rectifier diodes.  I also used the Sprague Orange Drop 716p instead of the supplied caps as they looked rather powdery.  I also added a 100uf cap at the end of the chain to keep everything quiet.  The amp has virtually no hum despite the tiny 1" shallow chassis.  Full phono stage and bass/treble controls too.  It sounds like an amp, decent highs and bass for its 8 watt output.  

(One of the 6GW8 tubes did not survive hibernation so waiting on a replacement.)