JMP-1: OD1.. what module?

Hi!
I have an SL+, 1086, Recto, and Top Boost.
I also have a Marshall JMP-1, and absolutely love the OD1 mode. None of my modules will do that OD1 sound. Tried same tubes in JMP and in modules (well, SL+ and 1086..), not close.

Been through the JMP-1 schematic, and dug up old conversations between Marshall techs and people questioning the op-amp thing (claiming the JMP-1 did not really use the tubes for gain). Wondering if a mod might help?

Using my JMP-1 through Greenbacks (25watters) and using good tubes, OD1 has little to no "fizz" (as some will complain of). I almost do not want to sell it, but I am dying for a Friedman *corrected* Brahma more. But, it would be nice to find something just for that OD1 sound!

Module? Or maybe a pedal? Wampler has some sweet Marshall tones, as well as others (BOR and BB Pre both get close, but are missing that "tube-ness" of OD1).

Thx for any help with this odd (re)quest!

The JMP-1 does have diodes clipping the waveform, so I'd suggest using a Plexi Module with a pedal in front.

I used a JMP-1 for years, sounded great for distortion or clean, but lacked for in between blusey type sounds due to the diodes

Any Marshall'ish module and a good pedal should get you close.

Some good pedal choices would be as follows:

Barber Small Fry or Burn Unit (basically a Small Fry with an additional clean boost function)
MI Audio Crunch Box
Marshall Jackhammer
Marshall Guv'nor

My favorites are the Barber unit's, but they are all good. The Marshall boxes tend to have that JCM 800 "buzz", so if you don't like that, go with Barber or MI, which are smoother like a Plexi or JTM45. I have a place for both of these sounds, so I have both a Small Fry and a Jackhammer.

but..doesnt the distortion in the JMP-1 come from the tubes running at high voltage?
I owened 2 and they were quite good..and the tubes within did seem to be doing THE REAL deal. (Right down to a nasty hum...not in the audio signal...but from high voltages present).

Yes- the tubes matter.
I went over the schematic, and then did some searching. I planned on calling Marshall to either get info directly, or an email to correspond with to get answers. In the end, I did find where someone else had already done just that.

Basically, the diodes only play a part in "shaping" the sound when the input is pushed harder. Any one who has played a later 800; a 900; the Slash amp; etc from Marshall have experienced a similar application of the diode thing. Supposedly Voodoo have a "diode removal mod."

I went on a quest for something new. I got ticked at tube stuff, but the problem is my own physical limitations. So, after selling most of my stuff, I figured why not try something new? How about a bunch of new? My problem with the JMP-1 was the same problem I had with the Triaxis (which I loved as well): digitally controlled parameters. Wanna get that "knob" between 1 and 2? 7 and 8? Oh- yeah, sorry.. no can do. I can sit with the Top Boost module, and barely tap the treble knob and end up tapping back n forth a few times just to get it "right." If it had regular pots that I could set EXACTLY where I want, I would have held onto it.. and possibly not even tried MTS.

Triaxis, JMP-1, GP-1000, Rock Master, some multi-FX boxes, POD, Axe FX, and so on. Tried 'em, and MTS came out on top (so far). The GP-1000 is unique as well. Wish I could mod stuff to make MTS modules do Triaxis Gain 2 (green and yellow), JMP-1 OD1, and GP-1000 pre emulations. Even so, I am actually happy

I played with the JMP-1 for over 8 years, and the OD-1 was sweet on that thing.
Now that I use the Randall RM4 I have been using the Brown module for that tone, and I like it better(it's a little warmer)!!!
Plus for gritty leads I "stomp on a Rat" just to push it a little over the edge.

So last night Im watching TV...its like 17 degrees here in NY last night..
and there was TV show all about classic albums. They weee covering Def Leppards "Hysteria". And lo and behold Phil Collen was talking about guitar parts and to his left are 2 JMP-1 s...he is playing threw them..and yeah the distortion QUITE FREAKIN NICE!!
But he must have them tweaked because mine never could do what his does (he had alot my distortion-saturation than mine ever did)..
I loved the OD on those,too (OD-1..if I recall correctly). But once I found the MTS..I could could get proper cleans..and a variety of distortions so...here I am in RM4 land.
To be honest...with all the variety its easier to run afoul and not get a great sound...but I wouldnt go back.
Still, a true JMP1 OD-1 sound is so useful at times..
dont ya think the SL-1 gets closest?

So last night Im watching TV...its like 17 degrees here in NY last night..
and there was TV show all about classic albums. They were covering Def Leppards "Hysteria". And lo and behold Phil Collen was talking about guitar parts and to his left are 2 JMP-1 s...he is playing threw them..and yeah the distortion QUITE FREAKIN NICE!!
But he must have them tweaked because mine never could do what his does (he had alot more distortion-saturation than mine ever did)..
I loved the OD on those,too (OD-1..if I recall correctly). But once I found the MTS..I could could get proper cleans..and a variety of distortions so...here I am in RM4 land.
To be honest...with all the variety its easier to run afoul and not get a great sound...but I wouldnt go back.
Still, a true JMP1 OD-1 sound is so useful at times..
dont ya think the SL-1 gets closest?

Hmmm... SL+ seems more... JCM800. OD1, JMP-1 in general, has this midrange and "diode smoothing" that I just love. At least I am guessing it is the diodes. BTW- really nice g9 Chinese unlabelled tubes were a HUGE part for me.

******... now I am getting real tempted to sell a couple modules and grab another JMP-1 (sigh)

Personally, I have nothing against diodes,per se.
I mean..who cares? So long as it sounds good..I use it.
But I was always surprized by the weight of the JMP-1 and the useless clean sounds. For a company that should know better...I was and remain disapointed.
And while Im whining...the JMP-1 always eminate this low hum from its box..like a loud 60cycle hum. I couldnt be near it..it was so annoying. And the effects loop was really odd. I tried it a bunch of ways..and it was never quite right. Yo much or to little..and some tone suckage going on.
Its all very opinionated...but I will stick with my MTS gear.
GtrGeorge

I had a Marshall JCM 900 50w, 2 channel head, w/4x12".
I only used it once onstage and in tandem with a Mesa/Boogie.
It didn't have the balls to carry itself on stage. It sounded too weak without the Mesa on.
Marshall's sound great in the studio, but you need a line of them to hear them well in a band. Even the 100 watt heads are thin sounding.
I think it's that sweet spot they have...as good as it sounds and as much as we like it, it gets lost in the mix. You need a fuller tone to cut through on stage.
Just my 2?

GtrGeorge! said:

Personally, I have nothing against diodes,per se.
I mean..who cares? So long as it sounds good..I use it.
But I was always surprized by the weight of the JMP-1 and the useless clean sounds. For a company that should know better...I was and remain disapointed.
And while Im whining...the JMP-1 always eminate this low hum from its box..like a loud 60cycle hum. I couldnt be near it..it was so annoying. And the effects loop was really odd. I tried it a bunch of ways..and it was never quite right. Yo much or to little..and some tone suckage going on.
Its all very opinionated...but I will stick with my MTS gear.
GtrGeorge

Click to expand...

Can I get an AMEN!!!!

The clean sounds did suck in the JMP-1, even AFTER I sent it to VooDoo Labs. I could have bought 2 MTS modules with that cash. I used the ADA MP-1 for my clean......I really like the clean in the ADA.

I never used the effect loop, I always ran my Delay, hint of reverb and harminizer in parallel with a Rane line mixer.

I too will stay in MTS land!!!

Try a Plexi module with a good pedal. I use the Barber Direct Drive. It's been a while since I played through the JMP1's OD1, but I definitely don't feel like I miss anything with the current setup.

Gain is at 11 o'clock, right on the edge of break up, add the Direct Drive and heaven.

JMP-1 Clean Tones; For best results run the power amp wide open and keep the Level control on the JMP-1 set low (IE; use it as an over all Master Volume). If you run the Level control higher then the cleans will distort. We have video clips on our site and on YouTube that demonstrate good clean tones from a JMP-1.


Hope it helps
Trace