Ace Tone Rockey tube amp rebuild in pictures

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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Mon Jan 07, 2019 6:12 am

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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Mon Jan 07, 2019 6:14 am

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tunghaichuan
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by tunghaichuan » Tue Jan 08, 2019 3:36 pm

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.

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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Sat Jan 19, 2019 3:08 am

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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Last edited by laurie on Sun Jan 20, 2019 6:55 pm, edited 2 times in total.

sclitheroe
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by sclitheroe » Sat Jan 19, 2019 3:22 pm

Well at least the name plate will be original :D Keep going!

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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Sat Jan 19, 2019 4:33 pm

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...

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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Sat Jan 19, 2019 8:59 pm

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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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Sun Jan 20, 2019 4:59 am

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...

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The_Doc
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by The_Doc » Sun Jan 20, 2019 9:24 am

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

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laurie
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Re: Ace Tone Rockey tube amp rebuild in pictures

Post by laurie » Sun Jan 20, 2019 2:47 pm

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...

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