Tube Amp Archive

Thank you, Stephen. You answered one of my follow up questions - should I make a VCT for the heaters. Is this still necessary with a field coil speaker? Lotta new stuff for me here. I thought this was gonna be an easy Sunday afternoon project. I have several drawings for the GA-8 though none are an ...

Hi all, I'm rebuilding the circuit on a 1957 GA-8 Gibsonette from scratch because there's a lot of previous work done to it and it needs to be un-screwed. There's a wire on the power transformer that I don't know what its function is. The PT is labeled, "Gibson KEA 166" and it should be original to ...

Thanks everyone for the help - awesome suggestions & info! I reached out to Ampeg and they were great. Per the serial number it's a 1958 Dolphin II model 6015. They said the schematics / wiring in those days were, "wily-nilly" so, "good luck!" They forwarded a couple of links: https://www.bluebookof...

It's got half the chassis so, no, it's definitely not playing anytime soon. The youtube video comment says it's a Dolphin and I think that's it. Now I gotta find a bottom chassis for this that won't cost a small fortune... Here's a Reverb ad for one that looks the bill: https://reverb.com/item/70793...

I was able to find this short video that appears to be the amp. Not much help though...

https://www.youtube.com/watch?v=2V1X7Cns0fw

Alright guys, what is this thing? Got this in an amp lot. The seller said he thought it was a Rocket. I've modestly scoured the internet and I just can't find anything that matches it. The tube chart says it's a, "MODEL 6015" for which I could find nothing. The closest match is a late 50's M-12 Merc...

Hi all, Ampeg and Hiwatt had a baby and hatched a Vibroverb. I saw an ad for this on Craigslist and I ended up grabbing it today. If I'm reading the date code on the speaker correctly this is a 1966 Sound Electronics Corp X305R. Info on SEC is extremely scarce but from what I can tell an Ampeg perso...

Nailed it! I would never have found that.

Thanks for the help!

-mac

I have an idea for a project and I need one of these component clampy things. I've tried many keyword searches but never get the results I want.

What is the proper name of this thing?

Hi guys, Update: I moved some stuff around and I was able to confirm the problem is the chassis layout. I relocated the pre & power tubes and moved the speaker jack. I had the speaker jack loose, turned the volume up to just below the problem spot, and moved the jack around getting it near certain c...

I build from scratch & I'm looking to do something a little different from a Fender. By the time I get to #3 I'll have finished a single and a double ended 12A_7 / 6V6 Fender amp. I would like to do an Ampeg b-15 clone in the future but I'm not ready to drop $400 on transformers just yet. I'm lookin...

Hi all, Build #1, the obligatory Champ clone, is almost done. #2, a Fender Harvard, is on deck. It's time to start researching, planning and ordering parts for #3. What do y'all suggest? I'm hoping to be able to tackle something a little more complicated so as to test my skills a bit. Maybe somethin...

We have a bingo! I moved the speaker jack. No change. I thought the logic made sense so I disconnected the volume pot and lifted it up away from the circuit. Meh... Finally, I disconnected the input jacks and lifted them away from the circuit - much better!! :D It looks like the major issue, as poin...

Is the speaker jack right next to the input jack on the bottom of the chassis? If so I would move it. Also the power tube is at the input. And the pot connected to the cathode resistor is right next to the input 68k’s which are also very sensitive. I would find the right cathode resistor and lose t...

HI guys, I thought I posted an update yesterday but I guess I didn't hit, "submit." EDIT:: I did post it - for some reason I didn't see the updates y'all gave me until after posting this post. I will look at all the suggestions - thank you very much!! Anywho - NFB removed from the circuit = no chang...