JMP-1 + Mark IV

[yettoblaster]

I would think that would work great.
My son's old guitar player had a JMP-1 and a Marshall Stereo, and I tried out his JMP-1 through my MarkIIB. Added pure aggression. 8)

 

[ibanez4life SZ!]

Rabies....I am very curious how the JMP sounds through headphones...I'd really appreciate if you could shoot me a little review when you get it. I'm not too happy with my Vox Valvetronix, as an amp in general, and with headphones, it sounds horrible.

Thanks!

 

[cant play pool with a rop]

Ibanez, remember I warned you about the Valvetronix??

 

[Russ]

How are you running it?

I used to have a JMP-1 and thought it sounded pretty synthetic compared to my JCM800 and my JMP 2204. It was already long gone though when I got my Mark IV. I can't imagine it sounding better than the Mark IV's preamp though if you are plugging into the Mark IV return and using it as a slaved power amp. Or are you using it in front of the Mark IV? I remember trying it in front of my friend's Marshall 1959 and it was really cool.

From what I remember the JMP-1 sounded decent as a headphone amp. I was using Sony Studio Monitors at the time. Just be sure to use "good" headphones because even with these the JMP-1 only sounded decent.

Are you running just a pair of KT-77's in the outer sockets or are you using them blended with a pair of 6L6's?

I would suggest using a good midi controller with the JMP-1. The 4 button Marshall one (MPM-4E? IIRC) kind of blows.

I have a guy that wants to trade me one for another preamp I have. I am sitting on the fence about it right now only because the other preamp is kind of hard to get and is out of production.

 

[Russ]

I haven't tried my KT-77's yet. I have had them for a couple years now and still have yet to try them. I am just enjoying my 420's still.

Heh, I actually sold my JMP-1 because I liked the preamp that I have better. The preamp I have has some cool goodies in it like a tuner, EQ, noise gate, reverbs, delays, choruses, flangers, phasers, etc. In addition to this, it not only does tube distortion via a pair of 12ax7's but also can do solidstate distortion should I find I need it (I doubt I ever would though). The JMP-1 just kind of paled to it or I would have sold it and kept the JMP-1 instead.

Right now, I might trade the guy though because I have decided that I really don't need the effects. I would want to buy a tuner and EQ though and maybe a noise gate and a reverb unit. It is just nice to have all that in 2 spaces if you know what I mean.

 

[disassembled]

I haven't tried my KT-77's yet. I have had them for a couple years now and still have yet to try them. I am just enjoying my 420's still.

Heh, I actually sold my JMP-1 because I liked the preamp that I have better. The preamp I have has some cool goodies in it like a tuner, EQ, noise gate, reverbs, delays, choruses, flangers, phasers, etc. In addition to this, it not only does tube distortion via a pair of 12ax7's but also can do solidstate distortion should I find I need it (I doubt I ever would though). The JMP-1 just kind of paled to it or I would have sold it and kept the JMP-1 instead.

Right now, I might trade the guy though because I have decided that I really don't need the effects. I would want to buy a tuner and EQ though and maybe a noise gate and a reverb unit. It is just nice to have all that in 2 spaces if you know what I mean.

Peavey Tubefex?

Greg

 

[Russ]

I don't recommend KT77 tubes with the Mark IV. I tried it without the JMP-1 in class A and simul as well. Doesn't sound as good for cleans and artificial harmonics as 4x6L6.

Thanks for the KT-77 review. I will probably sit on them until I can find some use for them now. I meant to use them in the JMP 50w I had. I just never got around to that before it went away.

 

[Blueracer]

tonite @ studio I ran the JMP-1 master right output into the mono return of the Mark IV effects loop. The Mark IV footswitch loop button had to be engaged for the JMP-1 to work. I noticed that the sound was different when I hit R1, R2 or lead with the JMP-1 in the loop. And the EQ button worked as well.

How do I completely bypass the Mark IV preamp when I have the JMP-1 in the effects return? I tried the left and right of the JMP-1 out into the mono and stereo return as well to no avail (the footswitch still works)...

The effects loop is at the end of the preamp but before the eq. Looking at the schematic I did not see anyway of getting around the eq section. If you don't want it you can just leave it off. The R1, R2, Lead issue stems from the switching in and out of the various presence controls. This is what you are hearing as differences between these modes. The presence is a frequency selective feedback loop in the power amplifier. There really is no way to disable this function. Select the one that sounds the best and leave it alone is the best I can advise. You can test all this out. With the JMP-1 in the loop and with the loop enabled none of your preamp controls should affect your tone. The eq, presence, master volume (output level), simul/class A, and pentode/triode all will affect how the amp sounds. Hope this helps.