Tube Amp Archive

Well just thought I'd post a little update. I finally got all of the old power caps changed and put a new three prong cord on. The amp sounds incredible now. No volume loss and just the right amount of overdrive. The only issue is a noticeable popping noise through the speaker when the volume on eit...

Excellent diagrams, Structo. Thanks a lot! I have no problem with bypassing the courtesy outlet, so that will A) make things safer by not having an ungrounded outlet and B) make things easier on myself with less wiring. I'm just waiting on a couple more caps. It's like a little kid waiting for Chris...

Thanks for the info guys. It's interesting that it's completely stock. My first thought was it's an AB165 that someone tried to convert into something else. I used to work on cars for a living and can sometimes tell when someone has been "into" something before me. This amp is starting to give me th...

Well I was looking around the chassis of this amp and there are a few things that are starting to look out of place here. There are a couple "cement blocks" and a orange Sprague Atom hanging out near the 6L6 socket. Also, the two 220k resistors from the local negative feedback loops appear to be gon...

Ahh, good point. I didn't even think about that. Actually, upon closer inspection (my eyesight definitely isn't any good), I've found that it's a 50uf@50v cap on the bias board. So 20uf would definitely be way too much of a drop. I have a 50uf@50v on the way, so we're good there.

Thanks, yeah I won't be messing with anything in there until my dad is available to either watch what I'm doing or do it himself. Sometimes I get just enough knowledge to get into trouble, and that's when I really have to be careful, heheh. On a sidenote, would a 20uf@500v cap be okay to replace the...

solderstain, sorry about that I missed that question earlier. No, I don't have voltage readings yet. Me being quite new to this, I don't exactly know where to take them from. My dad would, and I'm sure he will when I bring the amp to him. Only thing is he's away on business for a while and I don't r...

Yes, I replaced both power tubes with known good ones. It was not a matched pair, but they are both good. Actually, I have a weekend update to this one. I took a magnifying glass to the power caps and spotted a dark "burnt" spot on the bottom of two 20uf caps, plus the same two caps have very small ...

Thanks guys. I was considering changing out all the caps, just because I'm unsure of their age. They might not be stock, but they might also have been changed out 20+ years ago.

I'll order up a new set and pop them in while I'm cleaning everything up and try it out again then.

Hi guys, I scored a really great deal on a 1968 Silverface Bassman with the AB165 circuit, knowing that the amp would probably need some TLC. I have always had an interest in tube amps and have always wanted a Bassman, so I figured this amp would be a good place to start. I'm going to outline what t...

Hey guys, first I need to say I'm a complete newbie to amp building. But I've been poking around this forum for a while and it's full of great information and tips. Anyway, I'm interested in building a small amp and this particular kit caught my attention. I think it might be good as a first project...