Marshall 2203: JMP VS JCM800

[Bxlxaxkxe]

Anyone who says these amps sound the same has some of the worst ears in the history of guitar tone. Sure, they’re very similar in some ways, but they’re also so incredible different when you’re behind the wheel.

JCM800: Brighter, tighter, more pokey and aggressive

JMP: Saggier, fuller, somewhat dull high end comparatively

I actually think the JCM800 2204 sounds more like a JMP2203 than the 800 2203 does. Little more give to the feel, little more saturation (or appearance of it), but still a more articulate and bright version.

Boosting gets them more in the same ballpark. Straight in, I’ll take the 2204 for sure. Once boosted, it gets a lot harder to pick and is more about what the riff calls for

 

[rstites]

There is no change in the circuits in the switch from JMP to JCM800 trade dress. It's only an appearance change. All of these circuits have minor, iterative changes throughout their runs. If you are only comparing these 40-50 years down the line with component drift, not to mention any repairs or minor tweaks to the amps, it's impossible to say anything definitive about them.

 

[Bxlxaxkxe]

There is no change in the circuits in the switch from JMP to JCM800 trade dress. It's only an appearance change. All of these circuits have minor, iterative changes throughout their runs. If you are only comparing these 40-50 years down the line with component drift, not to mention any repairs or minor tweaks to the amps, it's impossible to say anything definitive about them.

I don’t read schematics but it’s been said there is higher preamp filtering on the early 800’s (vert input) compared to the JMP.

But that’s besides the point. Every 2-3 years I end up with one of each and of course I out them on a switcher cause I can’t help it. Same differences every time. As noted above. Every time. I guess headshells really do affect tone

 

[Bxlxaxkxe]

 

[alund]

View attachment 423160

I like that stoneage cab you got there on the side

 

[Bxlxaxkxe]

I like that stoneage cab you got there on the side

First one I ever ordered from John. Ended up getting like 6 more. I’m crazy

 

[Fusionbear]

I don’t read schematics but it’s been said there is higher preamp filtering on the early 800’s (vert input) compared to the JMP.

But that’s besides the point. Every 2-3 years I end up with one of each and of course I out them on a switcher cause I can’t help it. Same differences every time. As noted above. Every time. I guess headshells really do affect tone

I have never seen any difference in the filtering from JMP's and JCM800's.

What I have seen is a change in the filtering layout between first vertical input JCM800's and later horizontal input JCM800'S. I think it was 1984 that the horizontal inputs came out.

What is interesting is the the JMP's were all over the place with capacitor brands on the boards. I've seen Phillips mustards, WIMA, Siemens, the blue and yellow "cream puffs", etc... And these different cap brands do feel and have a slightly different frequency response to each other. I remember working on one that had the old, round WIMA coupling caps that sounded so killer.... unfortunately it was not for sale. The one with the Seimens coupling caps, not so much...

 

[aftec]

There are major differences in late 70s 2203/04, early 80s JCM800 2203/2204 and later JCM800 2203/04.
Firts they degraded the tranformers, than dropped the voltage significantly.
Still there are some duds and gems in any of them.
A very late JMP 2203/2204 and a very early JCM800 2203/2204 should be really close, becasue the only real difference is the faceplate.
When they run out of JMP faceplates they made the 4 hole JCM800, which actually is a 1959/1987.

 

[lespaul6]

I always opt for aggression over warmth every time, just fits me better.

 

[Bxlxaxkxe]

I always opt for aggression over warmth every time, just fits me better.

I hear that. I’m always looking to walk the line between both. With the JMP you’re fighting to add aggression, with the 800 you’re fighting to add warmth. It’s doable with either of them and is really just a matter of what mood you’re in

 

[FourT6and2]

Power supply. That's the key.

The schematics are all mostly the same. But what isn't shown on the schematics is voltage. If you want a tight, aggressive, angry sound out of these, get the PI B+ node cooking and properly ground the preamp filter.

The B+ in these amps is all over the place, with very little consistency. Marshall used random values for dropping resistors at times (and other components). Just whatever they had on hand at the time. And power transformers also varied wildly with respect to secondary voltage output. Some amps have B+ as low as 380v, some as high as 530v.

 

[rstites]

Variations in the transformers make the most sense for changes in tone. A higher B+ should give it more clarity and less distortion, but also support more punch in the power amp.

The capacitor discussion above is very interesting. I expected them to be a bit loose in swapping out close values in the 70's (and 60's) and not too surprised they sourced different brands of caps, but that's wild how many they used. It's like they just sourced the local electronics old stock store - anyone else recall those fondly - rather than having a proper supplier.

 

[Techdeth]

It depends on what I want . And it depends on the heads too . You know the 2203 I have . The highs on it are not dull

 

[7704A]

the local electronics old stock store - anyone else recall those fondly

Yeah, those are (increasingly were) awesome.

 

[Dale B]

It depends on what I want . And it depends on the heads too . You know the 2203 I have . The highs on it are not dull

My 2203 is big and warm sounding, but I like it that way. If I had a Hiwatt DR103 to run along side it, I could take over the world.

 

[Bxlxaxkxe]

Alright we’ve got some testing underway

 

[Techdeth]

Alright we’ve got some testing underway

View attachment 423224

How do they compare to mine ? You loved mine

 

[Greazygeo]

My 2203 is big and warm sounding, but I like it that way. If I had a Hiwatt DR103 to run along side it, I could take over the world.

Hiwatt you say? It is a good combo.

 

[Bxlxaxkxe]

How do they compare to mine ? You loved mine

Man it’s been too long to have any idea of a guess

 

[skoora]

I’ve always heard a difference between a JMP and a JCM.