Garage noob.

[h4x0r]

Hi All.
As the moniker suggests, I'm a bit of a hacksaw.

So you'll all be pleased to know I recently picked up a 1959SLP which is bright (ice pick anyone?) and LOUD as well... as loud as a Marshall is expected to be.

So I'm here filtering through a bunch of threads etc and looking for things to do to tame the beast to a more manageable state.

This is not an original 100w plexi, it's a 2013 "reissue" with the ST1 PCB etc inside and FX loop.

Thinking about a Fischer style master vol, and maybe some tone stack mods.... but it's tough. I can't decide whether to just leave it be or make it useable. Reality is that it was going cheap, and I was looking for a JTM45 reissue, but the price was far too sharp to ignore (plus it came with a JCM900 1960a cab) - about the same price as a JTM45 reissue on 'sale'... so it was a no-brainer.
I had thought of changing EL34's for something else... just not sure. All my fenders are 4x6L6 (Twins & a quad) so it makes sense to keep EL34s, but this amp is far far too bright. e.g. treble past 2 (8oclock) is unusable and harsh. Right now the jumpered channels have far too much treble even when blended to roll it all off, and the mids are also rather aggressive in adjustment... oh, it's plugged into a 1960AHW just in case anyone was concerned about speakers (G12H's).

So I'm going to have a look at the existing schematic and plug it into the TSC and see where it gets me, but I was hoping someone here might have already performed the 'experiement' and knows what doesn't work in the 1959 100w. it seems that tone shaping this thing is not as straightforward as an old blackface fender.

I guess the last option is to remove the ST1 PCB and go back to a PTP turret board. If so, suggestions would be good. I have plenty of epoxyglass board (but it's 4mm) and can make a turret board, but I don't have a template for a 1959SLP, nor do I know where to source one. I could for example just order a board for little effort from Hoffman and be done with it....

Suggestions would be appreciated at this point. If you have marshall experience on the heavy iron, I'm all ears.

I've done plenty of electronic work and thus have a decent workbench setup, and experience - also with 33/66kva HT so no safety police messages are required
I'm pretty sure that most people here understand what 'lethal' means. We've all had that mains ac tingle.

Favourite mod suggestions etc are welcomed and any other suggestions you see fit.

thanks in advance

[pompeiisneaks]

Yeah I would personally just remove the PCB and build a real JTM45 in there, but that's just me

There's probably a bright cap that could be removed or added to a switch to help tame the ice-pick harshness.

This is the schematic I found for that name: https://www.thetubestore.com/lib/thetub ... ematic.pdf

but not sure if that's it... If so it has a pretty weird pre and post volume set of caps, like a 2n2 paralleled with a 470p before, then a paralleled 4n7 and 1n into a paralleled 470p and 120p? WHA? no idea what magic they're getting at there

At any rate, I'm sure many more knowledgeable than I will chime in

~Phil

[xtian]

Don't be afraid to roll the Treble and Presence pots down to zero. Lots and lots of guitarists do this with Plexis, JCM800s, etc.

There are bright caps and treble peakers in the schematic you found that can easily be clipped to tame the brightness.C15 and C17 are the first things I'd remove.

[h4x0r]

Just in case anyone is not aware of what an ST1 PCB looks like (I'm sure most will) I've posted it below.

IMG_9157.jpeg

I have to admit I do like the idea of a turret JTM45/100 but at the same time I am curious as to what will 'get me there' on this board without spending $ on what may potentially be unnecessary.

Maybe attenuation is a better idea or a half-power circuit... who knows. I think if I went that route, I'd be better off buying an old used Hughes & Kettner triamp and messing with tone in a more "germanic" way. i.e. plug & play autobiasing instant-gratification tube swaps etc.

That's not what I'm about though. Call me a sucker for punishment. I'm going to get this marshall thing eventually.

PS: thanks Phil for the schematic. I had schematics, but they were not the correct version. Yours is. Thank-you!

[thetragichero]

bright sounds great in a band mix