20W Silver Jubilee Build

Marshall Amp Discussion

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timrobertson100
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20W Silver Jubilee Build

Post by timrobertson100 »

Hi folks

A few pics of a 6v6 silver jubilee built around 18W iron underway. Loosely based on the layout @dorrisant provided (thanks!), with most parts from Tube-Town and what I have lying around.
I had some original grey Marshall tolex from the early 90s to use and it just looks odd without the logo - figured there is enough here to indicate it's not trying to be the real thing.
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Colossal
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Re: 20W Silver Jubilee Build

Post by Colossal »

Looks great! That'll be a fun amp to play.
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timrobertson100
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Re: 20W Silver Jubilee Build

Post by timrobertson100 »

Thanks - I hope so

The PT puts out 300V, so I'm guessing I'll get ~400V on the plates.
It'll be a 2x 6v6 build, and my OT is a JTM45 (i.e. oversized) with both a 6.6k and 8k tap, and I can't decide which I should use... anyone has an opinion for this kind of build?

Thanks
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Colossal
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Re: 20W Silver Jubilee Build

Post by Colossal »

I built a 6V6 Plexi many years ago. It ran at 440V on the plates (JJs) and used a 7k6 20W Marshall OT. Fantastic sounding amp. I would probably go with the 8k taps.
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timrobertson100
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Re: 20W Silver Jubilee Build

Post by timrobertson100 »

Colossal wrote: ↑Fri Dec 22, 2023 12:17 pm I would probably go with the 8k taps.
Thank you for deciding for me - I've been stuck in the procrastinatrix
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dorrisant
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Re: 20W Silver Jubilee Build

Post by dorrisant »

Very, very nice! I had to do a double take.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
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timrobertson100
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Location: Denmark

Re: 20W Silver Jubilee Build

Post by timrobertson100 »

Thanks Dorrisant. It was your AO conversion that inspired me.

The Tube Town 18W extended PT has dual heater taps so I split the pre/power amp runs, elevating the preamp heater.
I powered the 12V relay using the 8V winding with the voltage doubler arrangement, like the Dumble 124.

The faceplate is the TubeTown "Silver High Gloss / Black" which looks great - it scratches more easily than others I've had. If anyone wants the artwork file, please PM me.

I had a 100Hz hum issue that Steve, Glenn, Bepone, and Martin helped diagnose in this thread (thank you all)
If I were to build it again, I'd put the rectifier, bias and relay power together on a board on the side like a Dumble, and rethink the capacitor placement - especially the preamp node sitting under the board.

Here's a vanity shot of the finished amp and it sounds as I had hoped - similar at lower volume to the original 2555 I have for now.
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