79 to 81 JMP 2204 ~= 81 to 84-ish JCM 2204?

[kysrsoze]

Hey, all.

I’ve been looking for an early 80’s JCM 800 2204, but they’re still going for lots of $$$. I do see the ‘79 to ‘81 2-hole 2204’s are sometimes more available and slightly cheaper. Ive read stuff that says they’re basically the same through this range of years, and I’ve looked at the schematics and they seem to cover this whole range of years.

Aside from some power tube differences, are the 2-hole JMP’s and JCM’s from 79 to 84-ish basically the same? I don’t really care about the style of the cabinet if they more or less sound the same.

 

[V-man]

Other than the individual build variances at the factory and the conditions surrounding the amp throughout its service life these past years, there is no difference from 1979-1983 (some early ‘84.

The difference(s) between your hypothetical 1982 JCM 800 2204 and a 1979 JMP 2204 should be no more and no less different (or a crapshoot) than a 1983 2204, or a 1981 JMP or an early 1984… etc.

 

[kysrsoze]

Other than the individual build variances at the factory and the conditions surrounding the amp throughout its service life these past years, there is no difference from 1979-1983 (some early ‘84.

The difference(s) between your hypothetical 1982 JCM 800 2204 and a 1979 JMP 2204 should be no more and no less different (or a crapshoot) than a 1983 2204, or a 1981 JMP or an early 1984… etc.

Thanks, V-Man. This gives me a few more options in snagging one in good shape at a decent price.

 

[Delaware48]

Love these amps. My 83 800 is a lifer

 

[79 2203]

I had 2203’s from 79*, 80 and 82 at the same time, and apart from some component brand differences and higher or lower voltages, they’re are all the same circuit and could be dialed in to be near identical.
Ive never noticed that JMP 2203/4’s are cheaper than JCM versions. Quiet the opposite actually.

*owned for 10 years now and sounding better than ever.

 

[Matthews Guitars]

The only real difference is that some time in the early 80s they revised the ST1 PC board to put the controls on the board, this can be identified by the two input jacks being aligned horizontally rather than vertically. Opinions vary on whether or not this makes the amp sound any different. But the circuit path remains the same.

 

[LyseFar]

I have a very late JMP 2204 - inside it is more or less a JCM800… or is it the other way around?
Great amp.

 

[Matthews Guitars]

JCM and JMP are both just a series designator. Even though some of the amps remained essentially the same and could be found in both series.

1980 was when the exclusive distribution agreement between Marshall and Rose Morris came to an end. Finally. RM had so much power over Marshall that they were more or less calling the shots. The end of the deal allowed Marshall to regain full control over its own distribution and the JCM800 series was created specifically to legally distance the products from the previous series JMP products which RM had some legal rights to. (Not clear on the details there...)

The launch of the JCM800 series, with a heavy ad campaign, was successful and likely saved Marshall from bankruptcy and dissolution. At the time they were down to just 13 full time employees. The JCM800 series became VERY successful, fortunately.

 

[Burk]

I have an ‘87 2204 that’s so nasty it sounds almost modded…..for sure a keeper…..but it’s not. Don’t be scared of the other years…..my $.02

Hey, all.

I’ve been looking for an early 80’s JCM 800 2204, but they’re still going for lots of $$$. I do see the ‘79 to ‘81 2-hole 2204’s are sometimes more available and slightly cheaper. Ive read stuff that says they’re basically the same through this range of years, and I’ve looked at the schematics and they seem to cover this whole range of years.

Aside from some power tube differences, are the 2-hole JMP’s and JCM’s from 79 to 84-ish basically the same? I don’t really care about the style of the cabinet if they more or less sound the same.

 

[Burk]

I have an ‘87 2204 that’s so nasty it sounds almost modded…..for sure a keeper…..but it’s not. Don’t be scared of the other years…..my $.02

I mean it’s not modded, but it is a keeper

 

[kysrsoze]

Thanks for that tip. Last night, I was doing more reading and listening to what I could from the late 80’s to compare, and honestly they still sound awesome and pretty much the same. I couldn’t discern much of a difference.

I’ve seen one or two comments that the late 80’s ones had a more scooped sound, but that doesn’t seem right. Consensus seems to be that the whole range pretty much sounded the same… which is great if I can save a few bucks and still get that same kind of sound. Plus I need some funds for the 4x12!

I have an ‘87 2204 that’s so nasty it sounds almost modded…..for sure a keeper…..but it’s not. Don’t be scared of the other years…..my $.0

 

[Tone Slinger]

Thanks for that tip. Last night, I was doing more reading and listening to what I could from the late 80’s to compare, and honestly they still sound awesome and pretty much the same. I couldn’t discern much of a difference.

I’ve seen one or two comments that the late 80’s ones had a more scooped sound, but that doesn’t seem right. Consensus seems to be that the whole range pretty much sounded the same… which is great if I can save a few bucks and still get that same kind of sound. Plus I need some funds for the 4x12!

 

[Tone Slinger]

The jcm 800 2204 has higher (B+) plate voltage than the Jmp 2204. Way back around '75 or so, Marshall lowered the 50 watt amps plate voltage as compared to the 100 watt models. Previously all 100 and 50 watt amps ran at the same voltage. I guess Marshall did this to try and make more of a difference between the 100's and the 50's, because the higher the plate voltage the more headroom and sturdier the sound is going to be when pushing the amp.
So this didn't affect the 2203's, 1959's, etc, but Marshall went back to using the same plate voltages ( both 50 and 100 watters) when the 800 series was released, so the jcm 800 2204 is going to be a tad louder (only at volumes way louder than useful) and slightly harder/tighter sounding.

 

[Ken Bob]

Interesting to read all the previous threads on this and other forums about this very same question. The more you read, the less you seem to be sure of whether the circuit is THE SAME, or if the circuit did change from the JMPs to the JCMs. So many "definitive" statements here though.

Anyone see this "official" Marshall video with one of their actual amp designers? In talking about the evolution from JMP to JCM MV's, he specifically mentions a change in the NFB with the 800s (at around the 8:00 mark in the video):



To make matters more confusing, while so many forum warriors say unequivocally "IT'S THE SAME CIRCUIT!!" (contrary to what the Marshall amp designer says in the vid above), there ARE, in fact, 2203/2204 schematics out there variously showing NFB coming from both the 4-ohm and 8-ohm taps, especially the earlier the drawings are. Did they make JMP MV's both ways from the factory? I assume that all 800 MV's are probably 100k/4-ohm, but if there are JMP MV's with NFB from the 8-ohm tap, that would account for a pretty big difference in gain, aggressiveness, and brightness - kind of like the way so many folks (like Marshall's amp designer) always say the 800s are "brighter and more aggressive". Kinda makes you wonder, doesn't it?

Aside from the NFB question, the capacitor makes and models definitely did change from JMP to JCM era though, and of course there was the change in filtering with the horizontal input amps that I think someone touched on above. Is that really all? I used to have a 2204 JCM with EL34s that was, in fact, brighter and more aggressive than the '79 JMP 2203 I currently have (which has the plastic lego caps).

I'm currently perusing my old photos to see if I can see the NFB tap in my '79...

 

[stickyfinger]

I know the USA amps had 6550 powertubes and feedback on the 8 ohm. Uk had EL34 4ohm.

Another thing to consider is some amps had .68uf on the presence control early on but this may be a pre 79 thing.

 

[Kinkless Tetrode]

Another factor about the 800s being brighter may be the speakers. The G12-65 was introduced in about 1978 and ran until 82 or 83. The G12-65 has wide dust caps and is usually less toppy. It may not be entirely coincidental that the amps got brighter during the G12-65 and the G12-80 era.

 

[stickyfinger]

The horizontals had different filtering and less 10k B+ filltering. Combined with a higher voltage power transformer the latter amps were brighter and more crisp. I'm not sure if any had lower voltage transfomers.

 

[Matthews Guitars]

Don't expect any of them to get any cheaper. There will never be more of the original amps made so the supply is going to slowly reduce, especially pristine examples. If you're waiting for prices to drop before buying, that's probably going to mean you just won't buy one.

 

[Welderbastard]

Prices have softened since "the end" of covid. There are deals available.
You just have to look.

 

[Antti Heikkinen]

Around here late 70s-early 80s 2203/4 go for around 1000€, while you can maybe get a 1959 for a bit cheaper, and a two channel 2210 or an 900 for maybe 850;- or so, and that's about the same for like JVM heads and most others as well. A JCM2000 could be had for maybe 550 or so now and then. A 50w in 2x12" combo could be 1100-1200, there's been one for sale for like a year in my town now but he's asking 1200;- so it might still take awhile to move.

Anyway...I think those single channel 50w heads are just about the best rock-'n'-roll machines ever made. Downright hard to make them sound bad in any way. I've had a few, sold one for 850;- just six months back or so.