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Heathkit AA-32 Rebuild

TerrySmith

TerrySmith

Active Member
Here's an AA-32 I've had for several years, it was an ebay purchase. It appears to be a low mileage unit, all cloth insulation is still soft and flexible and has all it's original Mullard tubes! Now the bad part, it looks like it was stored in a damp shed or basement for many years and became home for generations of mice, the aluminum chassis was heavily corroded, I painted it hammertone gold. I still need to repaint the cover.

I stripped it and used the chassis for a preamp project and then moved the preamp to another chassis except the phono stage.

Now I've returned it to an AA-32 with a few changes:
Power amp section is stock except added a buss bar ground and seperate cathode resistors and caps.
Phono stage is from the RCA tube manual, leftover from previous project.
IEC power connector.
New caps stuffed in old can.
Individual parts for tone controls, I've found the stock PEC's to be noisy.
Simplified linestage- line inputs go straight to volume control instead of being attenuated and going through half the phono stage.
DC for the preamp tubes.

This turned out to be a really sweet sounding amp!

MVC-043F.jpg


MVC-038F.jpg


MVC-039F.jpg


MVC-040F-1.jpg


MVC-041F-1.jpg


MVC-042F.jpg
 
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Nice job. :thmbsp: Can you post a list of the discrete components' values, that replaced the PECs? I have one of these with a bad PT, but haven't been in TOO big a hurry to work on it, because of those pesky PECs.
 
Can you post a list of the discrete components' values, that replaced the PECs?
Click to expand...

They actually list the part values on the schematic. The AA-32 schematic floating around on the web is kinda hard to read but you can barely make it out. The same PEC is used on other Heath units, FWIW.

There's also the "tone stack calculator 1.3" you can download and roll your own.
 
TerrySmith said:
Here's an AA-32 I've had for several years, it was an ebay purchase. It appears to be a low mileage unit, all cloth insulation is still soft and flexible and has all it's original Mullard tubes! Now the bad part, it looks like it was stored in a damp shed or basement for many years and became home for generations of mice, the aluminum chassis was heavily corroded, I painted it hammertone gold. I still need to repaint the cover.

I stripped it and used the chassis for a preamp project and then moved the preamp to another chassis except the phono stage.

Now I've returned it to an AA-32 with a few changes:
Power amp section is stock except added a buss bar ground and seperate cathode resistors and caps.
Phono stage is from the RCA tube manual, leftover from previous project.
IEC power connector.
New caps stuffed in old can.
Individual parts for tone controls, I've found the stock PEC's to be noisy.
Simplified linestage- line inputs go straight to volume control instead of being attenuated and going through half the phono stage.
DC for the preamp tubes.

This turned out to be a really sweet sounding amp!

MVC-043F.jpg


MVC-038F.jpg


MVC-039F.jpg


MVC-040F-1.jpg


MVC-041F-1.jpg


MVC-042F.jpg
Click to expand...

Beautiful Restore!
John.:music::D
 
Great job, I'm restoring a Olsen with EL84 tubes and it's starting to sound really
nice, I see that there's two long bars for the ground I was thinking of doing that
to mine but need the room. Good luck with yours.

Tube
 
I too echo the comments about this being a 'nice resto' project! It's truly 'professional' at all levels!! I keep hoping I'll rise to this level of accomplishment!

Can I get you to elaborate some on your changes to the line stage part of this amp? You mention that you've removed them from running through 'half' the phono section. I'm curious about just what changes you made here?

Thanks,

Tom D.
 
Hi Terry, great job with the Hk but i wanted to say that i like your Corvair. Way back when i used to play with cars, i had a Corsa and also a convertible. They were fun cars but the body was so prone to rust that i had to give them up.
 
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