BossAreaForum

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Cool!

About 20 years ago, I had a friend who scored a Deluxe Reverb amp at a pawnshop for $300US. At first I thought it was one of the reissues because it was so clean. But it had been kept under its factory cover and even had the original RCA and Mullard tubes. It looked brand new. It was a real '65, the pawnshop didn't know what they had. My friend offered to sell it to me for $600 and I'm sorry I didn't take him up on it. It's probably worth 3X that today.

Well... these old amps often have more issues than meets the eye.

After changing the caps and giving it a general check-over I fired it up for the first time and it had a few problems...
a) The tremolo did not work.
b) WAY too much hum and noise.
c) One of the new output tubes red-plated (grew very hot - too hot).

Ended up having to do a complete rebuild on the tremolo circuit - it works as it should now apart from a small "flutter" that I'll chase down tomorrow. I'd never learned how to read a vacuum tube Transfer Characteristic graph... I have now. Needed to understand whether the tube was OK so I could eliminate it as a culprit (it's non-standard so i couldn't just swap it).

And a complete rebuild of the output stage (the circuitry around the 12AU7 phase-splitter and EL84 power tubes). The old components (resistors and caps) had drifted and deteriorated so much that the bias point for the tubes was completely incorrect. Replaced everything including the tube sockets - the sockets had been damaged by the excessive heat of the original tubes failing.
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BEFORE
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AFTER. Red line is around the output stage (and part of the reverb circuit). The new tremolo circuit is above it (in the middle) with the two blue caps.
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Well at least the name plate will be original Keep going!

Yeah... the good news is the drifting component values in the preamp section aren't causing any issues and are adding to the vintage feel. So they can stay. The tremolo circuitry is not in the audio path, so has no effect on the tone. Plus most of the tone comes from the output transformer and speaker which remain

Oh... and about 20 hours and $150 in parts into it so far. Definitely only doing it for the "fun" of it...

Its been sitting on the bench powered up for over an hour with no visible issues. Just a little hiss and hum - no more than expected for a 50 year old hand-wired amp.

I'm calling it done.
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One last observation.

This amp is designed for a guitar plugged directly into the input. Does not take pedals well. Distortion is *thin*. Modulation and delay is OK applied to a clean signal.

But... crank the volume all the way up and you get really, really, nice EL84 crunch. With a vintage ceramic speaker (like a Greenback) it would sound even better...

Always good to see old kit coming back to life. Nice job Laurie and great pix. Really enjoyed this.

Ohhh. .. here's an interesting thing. https://en.m.wikipedia.org/wiki/Ace_Tone

Ace Tone is an early incarnation of Roland!

I knew the hardware and wiring felt familiar...