Marshall JMP 'must have' mods?

[reverymike]

Hey guys, what would you consider to be the 'must have' mods to a JMP 2204? I'm not talking about sending it out to Friedman, or Fortin. . .I'm talking about the simple stuff that people do to sweeten them up a little (not really gain mods). For example, I've heard that snipping the bright cap is really popular, or switching out values on a couple resistors, etc sweetens things a little.

Any tips?

I have another old Marshall that I'll have Friedman do up for me. I was just looking to sweeten this other amp up a bit.

 

[King Guitar]

Put a Soldano Hot Mod in it. Noisy but sounds good.

 

[Chubtone]

Put a Boss SD-1 or Ibanez TS-9 in front of it. There, it's modded and will sound killer.

 

[Vrad]

Put a Boss SD-1 or Ibanez TS-9 in front of it. There, it's modded and will sound killer.

This... LOL!

 

[glpg80]

Put a Boss SD-1 or Ibanez TS-9 in front of it. There, it's modded and will sound killer.

This... LOL!

+1

as stupid as it sounds, a boost pedal and a hot pickup is all you need for a stocker....

possibly cascade the bright and normal channels manually, but a good sounding marshall does not need much to give up the goods

 

[goldwing68nv]

Put a Boss SD-1 or Ibanez TS-9 in front of it. There, it's modded and will sound killer.

+100000000 this will "wake up" the beast and it will sound incredible! JMP's love this simple "mod"!!!

 

[ericsabbath]

most famous guys mods are kinda basic:
- changing the first couplings caps for lower values (usually around 1n to 4n7) to keep tone clear and mid focused
- adding cathode caps to the later stages to boost more mids and gain
- getting rid of the fizz with small caps (from 39p to 1n) wired to the ground or wired in parallel with plate resistors
- increasing the first gain stage plate resistor (usually from 100k to 150k, 220k or 330k) to get more saturation
- using smaller gain pots (100k, 250k or 500k) or small resistors (47k-220k) wired in parallel to the gain pot to ground, so the gain gets more open and crunchy, and less processed
- reducing input resistance for better dynamics and thicker picking response

other guys rewire the cathode follower as a 4th gain stage (like a Splawn or Cameron Aldrich), but that takes out a big part of the warmth and midrange openness, imo
moving the the master volume to a pre-tonestack position and wiring zener diodes to it is also a common mod (the "Jose" master)

if you can handle a soldering iron, you can do all these mods within a couple hours spending $5 tops
a brown eye or a jose mod are quite simple

 

[duesentrieb]

without hacking it I would always install a depth mod and change some values here and there to make it more "meaty"

 

[duesentrieb]

- reducing input resistance for better dynamics and thicker picking response

mostly to get rid of the nasty hiss when running idle, esp. after adding gain to it

 

[Vrad]

Put a Boss SD-1 or Ibanez TS-9 in front of it. There, it's modded and will sound killer.

This... LOL!

+1

as stupid as it sounds, a boost pedal and a hot pickup is all you need for a stocker....

possibly cascade the bright and normal channels manually, but a good sounding marshall does not need much to give up the goods

2203/2204's are already cascaded and have 2 inputs. 3 gain-stages on those.

 

[Marshall Law]

If it has 6550's, get rid of them for EL34's.

+1000

 

[ericsabbath]

- reducing input resistance for better dynamics and thicker picking response

mostly to get rid of the nasty hiss when running idle, esp. after adding gain to it

forgot to mention this
thanks

but I love how it affects the picking response
some may not like this mod cause the raw tone gets a lot thicker and bassier without so much signal getting blocked

I would skip the depth mod, though, unless it's a really thin sounding amp

 

[reverymike]

What about replacing the filter caps? What are the best ones to use?

 

[loudgtr]

Put a Boss SD-1 or Ibanez TS-9 in front of it. There, it's modded and will sound killer.

+100000000 this will "wake up" the beast and it will sound incredible! JMP's love this simple "mod"!!!

Boom!!!

If it has 6550's, get rid of them for EL34's.

Yes!!

without hacking it I would always install a depth mod and change some values here and there to make it more "meaty"

If you can find a tech who knows what he's doing this is a great idea

I had this done to an '85 2203 and it sounds so good with an SD-1 boosting it, I love it!!