Tube Amp Archive

I haven't seen a published schematic for it, but it looks a lot like the 65 Reissue with slight improvements to the bias supply and an added cap in the tremolo circuit. I based this conclusion on a quick examination of these photos. https://www.tdpri.com/threads/fender-64-custom-princeton-reverb-han...

Thanks for this post. I'm contemplating how to meet the requests of a client with a late 70s Princeton (non reverb) who really likes the sound of a Princeton Reverb, but never uses amp reverb, and doesn't want to spring for a vintage Princeton Reverb--and hates the reissues. I'm contemplating repurp...

There's also a "dull" cap at the end of the preamp right before the master volume. I tend to pull both out and replace them with a plate bypass cap on the final stage of about 680pF. Gives a more natural high end in my opinion.

Just swapping the resistor will be fine. I used a 5.6k in mine (I think). I did a deep dive on this amp over on the telecaster forum. Anything you'd want to know about tweaking it is either there or in my head yet to be written to that thread. I cover the effect of this resistor on the tonestack in ...

I know this is an old thread, but I came across it while servicing one of the these. I figured I'd add a clean image of the interior. This one has a few changes I made. Parallel first stage triode with resistor adjustments to keep the same frequency response. Push-pull 10% audio volume pot to replac...

Essentially even the typical 2.2k biased the tube cold enough in that application to run out of headroom in the AB763 style amps. The fact that the amp itself gets dirty around the same point as when this happens masks that issue. If you add a master volume control however the issue becomes more pro...

Do you have a coupling cap after the 3rd gain stage? As it is right now there's basically 147k to ground from that node.

Also I'd recommend going the other way with the reverb driver cathode resistor since it's got a MV. Try 1.5k to start.

On a hunch, could you temporarily tack a 10+μF cap across that gain stage's cathode resistor? I'm finding lots of examples of preamp tubes unable to cope with partially bypassed cathodes these days. If that takes care of it you have a leaky tube. You can try swapping it, but elevating the heater cen...

This is a very rough build. A burnt 1k dropper indicates a short of some kind after it. Given the amount of burns to the insulation it's possible that the orange wire going to your screens has burnt though insulation and is contacting the chassis, hardware, or nearby pins on the power tubes. I'd rec...

Hello , Thank you for the interesting link , I agree totally and understand what you mean. Of course Stevie ‘s hands were the major Parts of tone but tech side we can approach his sound with well prepped amp and having fun. It’s just an interesting quest and passion to try improving an amp to a per...

There's a Tone Quest article whereby the author gains access to one of Stevie's Vibroverbs--through less than above-board means. This makes the article hard to find online, but it's out there. They document Cesar's mad scientist mods to keep the amp tight at high volume. Transformer changes, smaller...

Hey Ian. Big fan of your work, and always dug the tones you got with your Super back in the 90s--and the vocals, especially on your more gospel type tunes, are inspired and inspiring. An idea popped into my head as I read through this thread. You mentioned liking some aspects of the Two Rock/Dumble ...

Made a bunch of changes and the amp is working now. The grounding was changed per Martin Manning's DR suggestions. V3 wiring was flipped around a bit. The first dropping resistor went from 10K to 12K lowering the voltage for B+C and B+D. The 47K resistor that sends some signal to ground before the ...