# Marshall JMP-1 Preamp



## JimiGuy7 (Jan 10, 2008)

Hey guys, just wondering about the JMP-1. Is it solid state? I know it has 2 12AX&'s in it but that does'nt mean much. The reason I ask is because I am thinking about buying a Marshall 9200 power amp and a JMP-1 but I also don't want a cold and shrill tone. Any reviews or clarificatin on this matter would be awesome.


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## GuitarsCanada (Dec 30, 2005)

I used to have one long ago. Combined with a good power amp they will crank out some great Marshall tones for you. You have to basically consider that as an effects unit running through the power amp in your rack. I believe thay have a bunch of pre-sets on them. Still fairly popular in the rack systems. The 9200 is a big mutha if I remember correctly, I think I may have had one of those at one time as well. Rack systems have not been as popular as they once were. I still have one with all my Rockman half racks.

They all use solid state components even with the pre-amp tubes


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## JimiGuy7 (Jan 10, 2008)

So, by saying that they all use solid state components, would that mean it leads more toward a solid state tone (ie. MG crap) or is it pretty decent replication of tube tone? What exactly do the the tubes do in the preamp?


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## High/Deaf (Aug 19, 2009)

Preamp tubes do a few things. Mostly they are the gain stage(s) - that is, increasing the signal level from the pickups enough to drive the power amp section. But they are also use to drive active tone stacks, reverb tanks, effects loops and as phase inverters.

The important thing, IMO, is that the signal path is all tube. While it may have xistors, I would hope they are used for switching, etc. and not as a part of the signal path. I would think the high-end pre-amps would be like this but I don't know how the Marshall is configured. Maybe someone else can help with that.


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## Andy (Sep 23, 2007)

Solid state =/= cold and shrill. Most likely, those two 12AX7s are the gain stages, and the solid state components take care of additional tone shaping. Absolutely nothing wrong with that -- the primary reason tubes are so desired (and transistors looked on with distaste) in a guitar amp is because of the way they behave when clipping. If the solid state components are just there for EQ and such, or a switchable boost that can easily be taken out of the signal, I doubt they'll take anything away from the warm tube gain.

Also, the power section contributes a huge amount to the tube sound. I'd much rather run a solid state preamp with a tube power amp than the other way around, and I think the underwhelming performance of many hybrid amps on the market illustrates this, as compared to the old Music Man hybrids (with an all tube power amp) which were quite well praised.


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## GuitarsCanada (Dec 30, 2005)

I would agree on the power amp statement. That JMP-1 is only going to sound as well as the power amp you are sending it through.


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## Jimi D (Oct 27, 2008)

I owned and used a JMP-1 for years... It absolutely does have some solid state circuitry in some of the gain stages, but IIRC there are FOUR channels available to you on these things - two "clean" and two "gain" - and they're all capable of some excellent Marshall tones... I ran mine through a Peavey 50/50 for a while, and then through a Mesa 20/20 and both sounded excellent. In my opinion, the JMP-1 is a great sounding unit, and if I were still using rack gear, I'd still have mine today. Iron Maiden use them in both their live guitar rigs to this day!


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## Guest (Jan 28, 2010)

Do you like the Smashing Pumpkins tone circa Siamese Dream? Because that is all JMP-1. Check their SNL appearance and you'll see Corrigans small rack is a Jmp-1 and a lexicon unit and that's it really.


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## High/Deaf (Aug 19, 2009)

Andy said:


> Solid state =/= cold and shrill. Most likely, those two 12AX7s are the gain stages, and the solid state components take care of additional tone shaping. Absolutely nothing wrong with that -- the primary reason tubes are so desired (and transistors looked on with distaste) in a guitar amp is because of the way they behave when clipping. If the solid state components are just there for EQ and such, or a switchable boost that can easily be taken out of the signal, I doubt they'll take anything away from the warm tube gain.



The other thing with tubes vs. xistor is tubes generally have larger voltage swings which can equate to more dynamic range. And I think, much like the weakest link of a chain, if anything in the signal path limits the dynamic range of the preamp, you will hear the limitation of that one stage and not all the other things that have lots of headroom. But I think reputeable manufactures figured this out long ago and design any xistor stages with this in mind.



> Also, the power section contributes a huge amount to the tube sound. I'd much rather run a solid state preamp with a tube power amp than the other way around, and I think the underwhelming performance of many hybrid amps on the market illustrates this, as compared to the old Music Man hybrids (with an all tube power amp) which were quite well praised.



Many years ago, I owned an amp with a s/s preamp and a tube power amp - I was looking for that tube power amp distortion. That was when I realized how loud 4X6L6's through a 2X12 can be. I still know a guy who plays through a non-MV Twin Rev and works it to power amp distortion. Beam blockers, boxes in front of the amp, whatever - it's still loud as shit. Sounds nice, but loud! Pretty tough to jam with him.


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## JimiGuy7 (Jan 10, 2008)

Great advice guys. Keep it coming. I appreciate it, but can I get some more reviews from some guys who have used the preamp and tell me what they thought of it? Maybe also let me know what you are running it through for a power amp.


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