My #34 mod

lespaul6

lespaul6

Well-known member
I did the Jake E Lee mod to my 2203 several weeks ago and decided to pull it out and try out the #34 mod, which is more my style. I used just a few parts to do this. I've seen some elaborate schematics using a lot more parts and the whole "hot shield" approach- I didnt want to try. Here is my version. I used the 470p on the 100r in place of the "hot shield" set up. No NFB manipulation.. just stock 110k to the 4ohm tap. I did not use the 150k resistor on the gain pot. I think it sounds really good and I no longer need to use an SD 1. Its a hard rock mod that will do old lynch and demartini as well. comments/critiques welcome
 

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So is it just stock 2203 plus the .1uF across the 10k and the two cathode caps on V2?

I did the JEL mod to a homebrew Superbass clone and it was really bright so I ended up putting a 470p across that added 220k resistor to ground (which in my amp ended up 330k).
 
Yes... .1uf across the 10k; .68 across the 820r; and 470pf across the 100k

I tried the 470pf across that snubber resistor at the top left of the schem but prefer it where the JEL has it

what was your NFB set up for the JEL? I thought it was really bright without doing the depth mod/ 47k feedback resistor
 
ah, I dug out the original schematic and realize that the 22n coupler goes to the low-sensitivity input...
 
tip: if you find it a bit ice picky, replace the 10k||100n cathode circuit with 4k7||220n or 3k3||330n.
 
lespaul6 said:
Yes... .1uf across the 10k; .68 across the 820r; and 470pf across the 100k

I tried the 470pf across that snubber resistor at the top left of the schem but prefer it where the JEL has it

what was your NFB set up for the JEL? I thought it was really bright without doing the depth mod/ 47k feedback resistor
Click to expand...
I also have the 470p across the 100k cathode resistor but this 470p is in parallel with the added 220k across the gain pot. I originally tried 1n there but 470p is better to me. It's only in circuit when in JEL mode.

This amp has a Depth control. It was a four-holer so I made one low input 'plexi mode' and one high input '2203 mode' with the separate gain pots in the other two input holes. Then all the other pots got moved over a spot leaving an empty hole for the Depth at the other end (where Presence was). Then you pull the Lo Gain pot for Bright (needed for plexi mode) and pull the Hi Gain pot for JEL mode. Borrowing from Mesa I call it the 2203++ mod.:cool:

EDIT: here's my schematic.
IMG-20220709-051835.jpg
 
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SpiderWars said:
I also have the 470p across the 100k cathode resistor but this 470p is in parallel with the added 220k across the gain pot. I originally tried 1n there but 470p is better to me. It's only in circuit when in JEL mode.

This amp has a Depth control. It was a four-holer so I made one low input 'plexi mode' and one high input '2203 mode' with the separate gain pots in the other two input holes. Then all the other pots got moved over a spot leaving an empty hole for the Depth at the other end (where Presence was). Then you pull the Lo Gain pot for Bright (needed for plexi mode) and pull the Hi Gain pot for JEL mode. Borrowing from Mesa I call it the 2203++ mod.:cool:

EDIT: here's my schematic.
IMG-20220709-051835.jpg
Click to expand...
very cool set up
 
Have you tried messing about with the V1A cathode and coupling cap values? I’ve been digging a 3k cathode and a 0.0022uf cap with a similar setup.
 
Chubbs said:
Have you tried messing about with the V1A cathode and coupling cap values? I’ve been digging a 3k cathode and a 0.0022uf cap with a similar setup.
Click to expand...
Are you adding some gain and slimming out the bottom with this configuration?
 
lespaul6 said:
Are you adding some gain and slimming out the bottom with this configuration?
Click to expand...
Yeah. The 3k in a way tightened up the low end through the mids where the 10k lacks. The 0.0022 Slims the bass while also adding a peaky quality to some duller frequencies in my particular setup.
 
Thanks for sharing all your revisions/tweaks on this circuit guys.. I remember years ago the mod was shared with me on the metro amp forum ( the official mod as it was seen in Slash's amp - or one of his 800's) and I thought it sounded great for "that" sound but really a bit limiting in that it was Slash's sound but a tad spikey for my tastes as well and I generally like mids and treb. Low in put plexi and high input 34'ish mod looks cool!
 
Listening to Eddy Lenz's amp here, I am surprised Schenker didn't have this as his go to. It is close to his parked wah tone but with more gain. That said, the 2205's sound great for both him and Norum

 
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