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Heathkit AA-100
Heathkit AA-100
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Old 28th December 2005, 06:10 AM   #1
imix500 is offline imix500  United States
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Default Heathkit AA-100

Hello all, so I've come across one of these for a very tempting price but I have a few questions to run by anyone who might lend some advice. After doing a good bit of research on this one I'm torn on whether it would make a good first piece to restore and mod.

(oh, a little quick background- I have a strong background in both electronics and audio as it's what I do for a living and am also familiar with tubes on the power and control side of things and have also restored several pa tube amps for bass guitar use)

Anyway I like the power output specs and I know the iron is decent, but I've read some pretty bad reviews about it. Namely, frequently cooked and extremely fragile pcbs and one of the the worst designed preamps in history. I'd like to fix it up, bring it up to as near factory specs at least, and then tweak it to my hearts content. It would be for the purpose of learning and also for daily use. So would this be a solid one to start with? If not, any suggestions? Thanks!
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Old 28th December 2005, 10:28 AM   #2
SHiFTY is offline SHiFTY  New Zealand
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I had one briefly and it did sound pretty good in a warm and woolly kind of way. The large output iron is top-notch and the output stage is pretty well-designed with a good amount of power. It also looked quite cool with the front all lit up (just like a 1950s bathroom!) However mine had bad tube sockets, dodgy PCBs and was pretty average cosmetically and needed all new capacitors and resistors. I used to run it with the cover off to see the tubes glow, but it was not all that neat inside, not to mention a safety hazard. I ended up stripping all the tubes and transformers and building a new amp from scratch.

The 7591s are very nice sounding as are the output transformers. There are also a lot of ECC83s in this unit which can be useful. If it is in mint condition then it is a viable candidate for a restoration, otherwise it's still worth getting as a parts amp. The transformers are about 7500 to 4/8/16 ohm.

Definitely a reasonable sounding unit, but yeah the wierd things about it (RCA connectors on the bottom plate!?!?) and the PCBs put me off running it long-term.
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Old 28th December 2005, 09:35 PM   #3
imix500 is offline imix500  United States
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Hey SHiFTY, thanks for the reply. Cosmetically this one is average. It looks like it's been sitting in a garage or shed for 30 years. Mostly dirt on the face plate and a light hasing on the chassis that should mostly clean up. The tubes look to be original which could be a good or really bad thing. I'm planning on an extensive re-work anyway if I get it.
I had a mental lapse about the preamp tubes, as this is the UK version (Daystrom) the ECC's would be nice.
But as you said it would be worth it for the parts if it turns out to be a disaster when I get it home.
Just found out there's also a Scott Stereomaster available that might be fun. Not sure of the model but it uses a pair of 6L6's in the outputs.
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