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And Finally Scored One of These

The JMP1 is so much better with good preamp tubes and a Voodoo Amps platinum tuneup. Def Leppard (Phil Collen) used them like that for EVER.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Regarding modding the JMP1:

Most mods where related to mod the internal pre-setted tone stacks for lead and clean. The JMP1 features a overall digital controlled master tone stack, but also have separate tone stack circuits internally pre-setted after the clean and the drive circuit. Alter these to taste and you can get some nice results.... Also nice were added grid stopper resistors at VB1a and VB1b also on VB2a, I'm not really sure if you can improve the tone with a mercury magnets mains transformer instead of the original transformer....this is what make's it a "voodoo"-mod I guess:lol

Cheers
P
Sort of. The two channels have preset tone stacks. Then there is a digitally controlled 4-band graphic EQ which is the B/M/T and Presence. This technique gets around the problem of trying to digitally control a tone stack. The Triaxis uses LDRs in place of potentiometers. The Soldano X-99 uses motorized pots. Both techniques being expensive. So the JMP-1 uses a fixed tone stack and then a digitally controlled graphic EQ.

The Axe-Fx model of the JMP-1 is "better" in the sense that the tone controls control the tone stack rather than a graphic EQ. You then have the separate graphic EQ to further tailor the sound. What I didn't do, and why people probably feel the model differs, is "normalize" the tone controls so that with B/M/T at noon the tone stacks match. On the Axe-Fx you might need to set the Bass to 3, Mid to 7, etc. to get the tone to match. I just used a standard Marshall tone stack whereas the JMP-1 uses a standard Marshall tone stack but the pots are replaced with fixed resistors but those values don't necessarily correspond to the pots at noon.
 

Wolfenstein98k

Power User
If I ever went bonkers and turned to "real" amps, I think I'd be really underwhelmed.

"Where's the cut switch on this Recto? Where did Jim hide the Character Freq knob on this damned 1969 Super Lead? Oh man, wish I didn't snip the bright cap... where's the button to put it back in?"
 

laughyouraxeoff

Experienced
Sort of. The two channels have preset tone stacks. Then there is a digitally controlled 4-band graphic EQ which is the B/M/T and Presence. This technique gets around the problem of trying to digitally control a tone stack. The Triaxis uses LDRs in place of potentiometers. The Soldano X-99 uses motorized pots. Both techniques being expensive. So the JMP-1 uses a fixed tone stack and then a digitally controlled graphic EQ.

The Axe-Fx model of the JMP-1 is "better" in the sense that the tone controls control the tone stack rather than a graphic EQ. You then have the separate graphic EQ to further tailor the sound. What I didn't do, and why people probably feel the model differs, is "normalize" the tone controls so that with B/M/T at noon the tone stacks match. On the Axe-Fx you might need to set the Bass to 3, Mid to 7, etc. to get the tone to match. I just used a standard Marshall tone stack whereas the JMP-1 uses a standard Marshall tone stack but the pots are replaced with fixed resistors but those values don't necessarily correspond to the pots at noon.
I haven't been this excited about a new amp a few months lol, but yeah man so stoked. I was wondering if the Axe Model will have any of the Voodoo Amp Platinum tuneup enhancements?
 

Hellbat

Fractal Fanatic
I haven't been this excited about a new amp a few months lol, but yeah man so stoked. I was wondering if the Axe Model will have any of the Voodoo Amp Platinum tuneup enhancements?
Well, since the one he bought doesn't have the mods and G3'ing involves measuring actual circuit values, I'd say chances of this happening are very slim. That's not to say someone clever wouldn't be able to figure out what advanced parameters to change to get you in the ballpark.
 

EJ James

Experienced
I had one back in 95. Couldn't wait to get rid of it. Hated that thing.

That's actually the year I became a Digitech fan with the GSP2101 + PPC210. That was the preamp/processor that turned this rig around 180º.

 
Last edited:

GreatGreen

Power User
Hey Cliff, what T/M/B/P settings would you recommend using to get the JMP-1's tone stack in the Axe-Fx as close to the real thing as it can be?

Also, what Graphic EQ in the amp block do you recommend using that most closely matches the JMP-1's?
 

toasterdude

Experienced
Marshall JMP1 | eBay

Hard to find in good condition.
Very cool. However there are a gazillion marshall flavors in the Axe already. What the world needs is a g3 version of my peavey tubefex! Lol

I went from ADA MP1 to Tubefex after also trying jmp1 and even triaxis.

The one sound I still miss when using modelers. I even bought one off ebay and paired with classic 50/50 to recreate my 90s rig minus quadraverb of course. I guess I need to profile that sucker into the KPA.

Maybe tone matching it with 5150?


Sent from my iPad using Tapatalk
 

zenaxe

Fractal Fanatic
Very cool. However there are a gazillion marshall flavors in the Axe already. What the world needs is a g3 version of my peavey tubefex! Lol
The Rockmaster would make more sense than the Tubefex, IMHO. The tubefex was an all in one programmable unit that included a preamp whereas the RM was a pure tube preamp (used pots instead of digitally controlled tone stack), my understanding is that the TubeFex's preamp design is a derivative of the RM design, as well. I have never played one but the Rockmaster was highly regarded, IIRC.

A 5150 amp model would be a good starting point for emulating the RM tones. Your 50/50 used EL-84s so change the tube type in the power section to EL-84, etc.

And just because we are talking preamps and I have a chance to:
+1 on any past, current, and future ADA MP-1 requests.
 

Shask

Inspired
The Rockmaster would make more sense than the Tubefex, IMHO. The tubefex was an all in one programmable unit that included a preamp whereas the RM was a pure tube preamp (used pots instead of digitally controlled tone stack), my understanding is that the TubeFex's preamp design is a derivative of the RM design, as well. I have never played one but the Rockmaster was highly regarded, IIRC.

A 5150 amp model would be a good starting point for emulating the RM tones. Your 50/50 used EL-84s so change the tube type in the power section to EL-84, etc.

And just because we are talking preamps and I have a chance to:
+1 on any past, current, and future ADA MP-1 requests.
The Peavey Ultra Plus head, or the Peavey XXX head would probably make even more sense, since they come from the same design family....
 

ocaptainjr2

Experienced
The Rockmaster would make more sense than the Tubefex, IMHO. The tubefex was an all in one programmable unit that included a preamp whereas the RM was a pure tube preamp (used pots instead of digitally controlled tone stack), my understanding is that the TubeFex's preamp design is a derivative of the RM design, as well. I have never played one but the Rockmaster was highly regarded, IIRC.

A 5150 amp model would be a good starting point for emulating the RM tones. Your 50/50 used EL-84s so change the tube type in the power section to EL-84, etc.

And just because we are talking preamps and I have a chance to:
+1 on any past, current, and future ADA MP-1 requests.
I would gladly send my Rock Master to Cliff. I have owned 4 or 5 over the past 20 years and they each sounded different. I still have my original/'best' one at home. I also used a 50/50 with EL84's for a long time and it was great. I've tried to reproduce the tones, but can't really get close. Guess I could look at how to model a preamp without a power amp in the Tone Match section...
 

Dutch

Fractal Fanatic
I had two Rockmaster pres at different times. Both with the same power amp MESA 50/50 and Marshall 1960A cab.
I loved the first one, second sounded indeed quite different. Not so smooth, more edgy. Still good but the first one was better.

Had a M/B Studio preamp in between that I couldn't get any good sound out of.
 
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