Some pics of my Heathkit conversion

[CitizenCain]

Here are a few pics of the conversion I did for a friend of a Heathkit AA-23 mono hi-fi amp transplanted into a Princeton Reverb repro chassis. It's really more a of a re-creation than a conversion. I couldn't use as many of the original parts as I first intended, but the trannies, octal sockets, pots, tone network package, coupling caps and some misc resistors are from the donor. The circuit is very much like the original Heathkit circuit, just a couple mods to make it more suited to guitar use. Tube compliment ended up being 2x 12AX7, 1x 12AU7, 2x 7591 and 1x GZ34. The major changes to the original circuit consist of a parallel first gain stage with V1, altered coupling cap values, adding some cathode bypass caps and adding a PPIMV.

It turned out pretty nice, I think. It sounds good, has a little hum and hiss but nothing extraordinary. It's quieter than a Custom Vibrolux Reverb It crunches up really good, in fact it's very gainy. But, it cleans up remarkably well with the guitar's vol control. It's a little stiffer than I wanted, but I think that has a lot to do with keeping the original filter cap specs. It's pretty heavily filtered with 60mfd on the OT, and 40mfd in the PI and preamp stages. Also, the GZ34 recto doesn't offer up much sag. Still, all-in-all it sounds pretty nice and I think he's going to like it.

[corworld]

Nice point to point. The grounding scheme looked especially hard to do.

[CitizenCain]

Thanks, corworld This was my first attempt at p-t-p, I just hooked 'em up where they seemed logical!

[Borg54]

It's only a suggestion, but you really don't want to piggy back your bypass caps on top of resistors like that. The heat from the resistors will bring about premature cap. Failure. For the first attempt at real PTP, it looks good for a green project.

[CitizenCain]

Thanks, Borg. That's why I come to this forum, for insights like that. I'll pay attention to that when I do mine He had two of these Heathkits and I got to keep one as my payment.

[Borg54]

Yeah, that's the same way I learned, but I did have a slight edge as my father was an amp tech so I picked up alot through osmoissis while I was growing up. And yes that's a good deal on the heath kits.

Me, I am buried in amps. I had a little seed money so I ran an add on Craigslist stating that I buy dead amps. It worked better than I had expected. But if you really want to learn fast, get into the repair side of the business. Also there is more $ in doing this, than chasing the pipe dream of being the next Leo Fender. I know several guys that are struggling with this and starving. It's really like this - the old generation is dieing off, now who is going to pick up the torch on a trade that is no longer taught. And as long as there are electric guitars, there will always be tube amps that need repair.

Good luck with the heath kits.