Modded my homemade 2204 today

[Hipster Salad]

I think the JEL mod is my favorite setup for a 2204. It's what the 800 should have sounded like in the 80s. It's no wonder so many players were doing similar mods back then. Or even boosting it.
The stock, unboosted tone of the 800 is not all that great IMHO.

Last year I did a big 2204 comparison and the JEL was my favorite by a large margin.

100% agree with this. I had a horizontal input 2203 years before I dipped my toes into modding, and honestly I hated how it sounded stock, and as a result I got rid of it within a few weeks. Biggest amp sell regret ever (bought it for $250)

Caveat: I didn't try boosting it, and can't remember what speakers I was using, maybe a Windsor cab or something.

[MacaroniSalad]

Yep, stock 800s straight in are not especially inspiring. Maybe a good 2205/10.

All bets are off if you can dime it, but that's not usually an option.

[Tortuga]

Well... almost a year later


I'm seriously considering trying the JEL mods to my new 2204 build (thread here, if anyone interested: viewtopic.php?f=5&t=54405), but want to be able to switch between stock and the modded version. I really like what you did with yours. For the stuff you have to change that doesn't wind up on the switch (like the 22n to 2n2 cap on the gain channel input, NFB/fixed depth changes, and cathode bypassing on V2), how does that affect the stock tone and feel?

Changing the first coupling cap from 22n to 2n2 cuts a good amount of bass, so it makes it tighter and more crisp in the lows, then with the depth control you sort of bring it back at the end of the signal chain. Cathode bypass caps usually bring in a little more midrange and a touch more perceived gain if I remember right.

I went back and forth with the 34 and JEL mods on my 2204, and ended up just keeping the JEL style mod personally. Did a few minor tweaks on top of it, and it's a pretty good contender for early VH type tones.

Very cool - sounds like the tone shifting at the start gets balanced in the end, and am really interested now. Thanks man!

I think the JEL mod is my favorite setup for a 2204. It's what the 800 should have sounded like in the 80s. It's no wonder so many players were doing similar mods back then. Or even boosting it.
The stock, unboosted tone of the 800 is not all that great IMHO.

Last year I did a big 2204 comparison and the JEL was my favorite by a large margin.

I really have a feeling this will do exactly what I'm looking for - all the good shit, just more of it

My Egnater Seminar amp has the V1 mod on the second gain stage cathode. 2.7K resistor with a .68 bypass cap same as V1A. Depth mod with a similar setup except on the 8 ohm tap. I may switch it to 4 and give that a whirl. It’s a pretty awesome little 50 watt amp.

I wound up posting the question about which tap to use for the NFB loop (saw different stories on different schematics), and wound up using the 4-ohm, since that's what Marshall specified. Would love to hear your thoughts if you do switch it

I think the JEL mod is my favorite setup for a 2204. It's what the 800 should have sounded like in the 80s. It's no wonder so many players were doing similar mods back then. Or even boosting it.
The stock, unboosted tone of the 800 is not all that great IMHO.

Last year I did a big 2204 comparison and the JEL was my favorite by a large margin.

100% agree with this. I had a horizontal input 2203 years before I dipped my toes into modding, and honestly I hated how it sounded stock, and as a result I got rid of it within a few weeks. Biggest amp sell regret ever (bought it for $250)

Caveat: I didn't try boosting it, and can't remember what speakers I was using, maybe a Windsor cab or something.

I've been out all my basic OD pedals (SD1, TS9, and Duke of Tone) and the MXR EQ in the front, as I haven't really jibed with the unboosted sound yet. So far, SD1 is my favorite, and my son liked the TS9.

Granted, I haven't really been able to run the thing at decent volume yet, so I'm sure that'll be a whole different thing, but for now, I'm definitely on the hunt for a little more refinement, and hoping this JEL mod will get me there.

Yep, stock 800s straight in are not especially inspiring. Maybe a good 2205/10.

All bets are off if you can dime it, but that's not usually an option.

Can't wait to get somewhere where I can dime it



Thanks for all the help (and to OP for allowing the thread hijack )

[Hipster Salad]

Not sure if this has been mentioned yet or not, but seriously you need to check out Jason Tong/Headfirst channel on YT. Lot of info on the 2203/2204 circuits including JEL mods, bright caps, horizontal vs vertical input JCM800, etc.

[Tortuga]

Would you guys mind posting up the changes you'd recommend for the JEL mod? Really liking the sound of that - especially if it's switchable back to stock

First coupling cap change from .022 to .0022 (I always like this on a 2203/2204 regardless of what other mods I'm doing)
Change the 10k cold clipper cathode to a 2.7k, and bypass with .68uf (usually electrolytics recommended for this one)
Add a 220k across the outer lugs of the Gain pot
Bypass the 3rd gain stage 100k cathode with a 470p
Add a depth control pot, or just wire in a 220k // .0047 cap
Change NFB resistor to 47k, and move to 4 ohm tap - again another standard mod I like with these amps
(not part of the JEL mod, but might be worth looking at - change PI 'fizz cap' from 47pf to 100pf)

*You can drop a 3k3 or similar parallel on the stock 10k cold clipper to bring it down close to 2.7 if you don't want to remove that resistor
**Drop a 50k parallel on the factory 100k NFB to bring it down close to 47k if you don't want to remove it.
***Lar-Mar style PPIMV is also not a bad thing if you are playing lower volumes. I have mine set at noon almost all the time.

If you want a little more of a Jose/Friedman style thing, you can change the V1b plate from 100k to 330k and bypass with a 470p

Anyone know where to get the .68uf electrolytic caps? I've found everything else easy enough, but this one is pretty elusive. Mouser shows they're able to supply them, but it's a LOOOONG wait time.

[Tortuga]

Fuck it… ordered a .68uf Mallory for now. If anyone has a source for the electrolytic, I’ll order one and give it a try. For now, I’ll do what I can.

Going to use a 1meg push-pull to replace the preamp gain pot, which will allow me to switch the cathode structure (from stock cold clipper to higher gain) and the resistor in parallel with the gain pot. That’ll let me choose the mode using ledvedder’s switching circuit, without having to drill a new hole.

[Zozobra]

It's absolutely fine to use a film cap in application. It will sound a little different as they respond 'faster' than an electrolytic. Some people prefer film bypass caps in high gainers for this reason. Crazy that you can't source an electrolytic as that's a super common value.

[Tortuga]

Spent a good part of yesterday afternoon updating my 2204 with the JEL mods, using ledvedder's switching idea so that I can switch in/out the different cathode and gain pot mod using a push/pull switch (so I don't have to drill any additional holes for switching). Looks completely stock, and HOLEY BALLS the thing sounds killer!

Will post up a diagram later showing how I did the switching, in case anyone digs this up later and wants to try it out. Pics, clips, and details will be posted on my own build thread, since I've already hijacked/polluted this thread enough. Thanks for all the ideas and help, everyone!!!!