SuperBass-ish to JEL-ish mod; clip added

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SpiderWars

SpiderWars

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My Tweed Bassman gets the clean work over it and my homebrew SuperLead gets the dirty work over it so my homebrew '68 SuperBass doesn't get any love. So I decided to do a PLexi/JEL type mod. But then I found out one of my 1M-A pots with DPDT switch has a 7mm shaft and putting that in a previous input jack hole is just shitty. So I'll pause and get some 1M-A DPDT Bourns with 3/8" shaft. Each of the old Bright Channel input jacks get a 1M gain pot with DPDT switch. One for the JEL Gain switch and one for the Gain 2 Bright switch (needed for the Plexi mode). Since that freed up a panel spot I slid everybody down and put a Depth control with push-pull NFB switch where the Presence was. All cleaned up and ready to go. It's not really that much from here once I get those pots.

IMG_20220327_135550.jpg



EDIT: Here's a clip I posted later itt. 2203+ mode then with SD1 then 2203++ mode then with SD1 then a noise floor demo.

 
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SpiderWars said:
If I get those pots before next weekend I should be able to finish it. At least the initial build...and hopefully that's about the extent of it. It might need tweaking.
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I'm excited to hear what you have in mind! Most JEL mods ive heard were done with 2203 and 2204s obviously, so im curious to see how it sounds.

Tiago has a hermannsson modded superbass that sounds absolutely incredible - i think the superbass is perhaps underrated as a marshall and for mods :unsure:
 
DanTravis62 said:
I'm excited to hear what you have in mind! Most JEL mods ive heard were done with 2203 and 2204s obviously, so im curious to see how it sounds.

Tiago has a hermannsson modded superbass that sounds absolutely incredible - i think the superbass is perhaps underrated as a marshall and for mods :unsure:
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I recently bought an '80 2203 and so this mod has been on my mind. Doing it to this homebrew keeps me out of that Marshall. I'd like to keep that relatively stock.

A SuperBass is usually just a few parts away from a Superlead. And AFAIK they used the same parts.
 
SpiderWars said:
I recently bought an '80 2203 and so this mod has been on my mind. Doing it to this homebrew keeps me out of that Marshall. I'd like to keep that relatively stock.

A SuperBass is usually just a few parts away from a Superlead. And AFAIK they used the same parts.
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Yes, but obviously the "lore" and desirability (and price) isn't the same in peoples minds, for some reason.
 
Nice man!

The JEL is a killer Marshall mod. I did it to my 80’ JMP a while back.

I use those 1MA Bourns push pulls. Much nicer than the Alphas. Better feel to the switch and the torque of the shaft is better. Just have to be real careful about heating them too long on the lugs. They burn up easy compared to the Alphas. Must be something to do with the carbon track composition.
 
RedPlated said:
Nice man!

The JEL is a killer Marshall mod. I did it to my 80’ JMP a while back.

I use those 1MA Bourns push pulls. Much nicer than the Alphas. Better feel to the switch and the torque of the shaft is better. Just have to be real careful about heating them too long on the lugs. They burn up easy compared to the Alphas. Must be something to do with the carbon track composition.
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Thanks! Any tips on relabeling the front panel? I have one of those Brother portable label makers but only clear and black tape. Do they make a tape that matches? Or maybe obscure the old label with gold somehow (Sharpie?) then put clear label tape over that?
 
SpiderWars said:
Thanks! Any tips on relabeling the front panel? I have one of those Brother portable label makers but only clear and black tape. Do they make a tape that matches? Or maybe obscure the old label with gold somehow (Sharpie?) then put clear label tape over that?
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They make gold tape with black lettering. It won't be an exact match but it'll look decent.

Typically when I added labels to Marshalls I used clear with black lettering. Most went in places that were already blank. If I had to go over something that was no longer needed I used nail polish remover to take the original silkscreening off. Works really well.

This is how I did them typically.


m7yYzOpl.jpg
 
Cool... did you do the 47k feedback resistor to the fixed depth set up and then to the 4ohm tap- from the schem. Or did you do 68k like redplated does? I tried both yesterday and I like the extra zing from the 68k. The 47k just sounded a little too tight and clean... but still sounded good, of course.
 
lespaul6 said:
Cool... did you do the 47k feedback resistor to the fixed depth set up and then to the 4ohm tap- from the schem. Or did you do 68k like redplated does? I tried both yesterday and I like the extra zing from the 68k. The 47k just sounded a little too tight and clean... but still sounded good, of course.
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Since I had the extra spot from using two of the inputs for the gain controls I will have an actual Depth control on the front panel and that Depth control will be push-pull to select two different NFB resistances. My plan is to use the stock 47k/4ohm and then something more than that when pulled (Pull Raw). But that's a type of thing that will likely get tweeked at the very end.

But I agree with your sentiment tho...too much NFB kind of neuters it.
 
Still no pots but did everything I can do without them. The input wires/grid stoppers are pretty rigid at the socket but I wish more so. I have standoffs but didn't want to use one.

And very convenient and lucky that I just happen to have that big 10K carbon comp resistor...that's a long stretch between turrets that most of my resistors couldn't make. I don't have that in any other value but 10k. :LOL:

IMG_20220329_183626.jpg
 
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RedPlated said:
They make gold tape with black lettering. It won't be an exact match but it'll look decent.

Typically when I added labels to Marshalls I used clear with black lettering. Most went in places that were already blank. If I had to go over something that was no longer needed I used nail polish remover to take the original silkscreening off. Works really well.

This is how I did them typically.


m7yYzOpl.jpg
Click to expand...

What size tape do you use? 1/4"?
 
SpiderWars said:
Still no pots but did everything I can do without them. The input wires/grid stoppers are pretty rigid at the socket but I wish more so. I have standoffs but didn't want to use one.

And very convenient and lucky that I just happen to have that big 10K carbon comp resistor...that's a long stretch between turrets that most of my resistors couldn't make. I don't have that in any other value but 10k. :LOL:

IMG_20220329_183626.jpg
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What shielded cable do you use?
 
The Lo Gain jack (SuperLead with 22n coupler) and pot/switch work and sound great. And the 'stock 2203' mode of the Hi Gain jack sounds great and having that extra gain control with Bright switch (4n7) is actually quite useful. Normally that pot would be dimed anyway but if you engage the Bright cap and dial back that gain control a tiny bit it tightens up a little.

But when pulling the Gain switch it's too bright. Not "totally un-useable brash/bright" but just too bright, especially compared to 'stock 2203' mode which is already kind of bright as it should be. I tried diming that Gain control to determine if it's the 1n Bright cap but it's still really bright and the 'stock 2203' mode sounds fine with it. I think it's all wired right and everything seems nominal otherwise. Noise floor is really good. I could try a cap across the 220k resistor to ground that is engaged with the Gain switch and doesn't affect any other mode. But that seems bandaid-ish.

IMG-20220330-204844.jpg
 
Well I shoehorned a 1n cap (identical to the the Bright cap on that bottom volume) across that 220k resistor* you can see some of on that bottom switch. So it only affects the Hi Gain input and only when the Gain switch is pulled. That's better, it's closer to what the 'stock 2203' mode sounds like just more gain.

It's actually 270k not 220k. Why? Because I have an extra 1M to ground at the second jack that's normally not there. That renders that Gain pot to ~500k which I think is fine with the 'stock 2203' mode, it mostly just tightens it up and doesn't remove as much gain as you'd think. But I thought I'd get it back to where it would be without that extra 1M to ground when flipping the the switch...since I could.

I already like it this way more. It still has a great plexi mode that sounds as good or better than it did before plus a 2203+ mode and a 2203++ mode. It's bright but most Marshalls are at these volumes I'm playing it at so far. This one has a Merren OT.
 
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