Self-built JMP Super Lead 12xxx and guitar volume scratch

Info for maintaining and tweaking your amp to perfection.

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Blues1911
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Re: Self-built JMP Super Lead 12xxx and guitar volume scratch

Post by Blues1911 » Thu Jul 25, 2019 11:48 am

UPDATE: time is a tyrant, so just a few days ago I've been allowed to re-built the whole circuit, after a VERY long time, using the excellent Valvestorm turret boards. Result: the scratch is now gone, so the problem was DC leaking between the two contiguous turrets where 68K and 100K cross (on V1), as correctly diagnosed.

Hope that my experience can be of some help to everyone who could need.

https://hosting.photobucket.com/images/ ... fit=bounds

https://hosting.photobucket.com/images/ ... fit=bounds

(sorry but, for some reason, forum platform can't allow me to share pictures from Photobucket anymore)

Not my cleanest build, but quite satisfying nonetheless. The noise level is higher than my other amps (JTM 45/100 and Bluesbreaker above all), but still acceptable. I'm giving some additional care to the lead dress, also because the green wires that connects V1 and V2 cathodes are microphonic (especially the one on v1 Pin 6, which is TERRIBLY microphonic, at the point that gives a distinct HMMMMMMMMMM when tapped). Plus, with no attenuation and everything dimed there's some high frequencies oscillation that I'd like to solve.

If someone can share here the threads where the Super Lead's suggested lead dress is extensively explained, I'd be grateful.

Cheers!

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neikeel
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Re: Self-built JMP Super Lead 12xxx and guitar volume scratch

Post by neikeel » Thu Jul 25, 2019 1:44 pm

Looking at your pic you have the blue plate wires sitting up in the air. They need to be pushed straight down to the chassis floor and moved away from the heater wires. The yellow cathode wires can be shortened too.
The green grid wires should be shortened too and kept away from the heaters.
Neil

Blues1911
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Re: Self-built JMP Super Lead 12xxx and guitar volume scratch

Post by Blues1911 » Thu Jul 25, 2019 4:06 pm

neikeel wrote:
Thu Jul 25, 2019 1:44 pm
Looking at your pic you have the blue plate wires sitting up in the air. They need to be pushed straight down to the chassis floor and moved away from the heater wires. The yellow cathode wires can be shortened too.
The green grid wires should be shortened too and kept away from the heaters.
Tube sockets wires are indeed longer than necessary - I will provide soon according to what you've suggested. Thanks!

Any other input, suggestion or recommendation is warmly welcome :D

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Re: Self-built JMP Super Lead 12xxx and guitar volume scratch

Post by RockinRocket » Fri Jul 26, 2019 8:04 pm

RockinRocket wrote:
Sat Jul 07, 2018 8:05 pm
Are we talking about modulous amps boards? IVe used them with zero issues.

LOL I was wrong about this. The Modulous boards are conductive.. it sent me banging my head against the wall looking for the problem. I thought 60 mA was normal and ok and probably just the Mustards leak a bit. Mustards dont leak nor do Lemco micas and neither do the boards in original Marshalls.

I talked to Mike from Modulous and he said hes only had one report of his boards being conductive. He said the customer applied a solvent to wipe off excess soler flux. In my case, possably the moisture from my hands were enough to upset the board or the Modulous boards just plain suck.

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