Old JCM800s

[B2D]

Lets say I wanted to buy an old Marshall JCM800... which version do you guys personally think sounds best and why?

Also, I once heard someone say that some 800's used a tube to create their overdrive/gain, and others used a diode to do it. I know what this means, but is it true? Which ones use the tube? How can I tell the difference?

~~

I'm looking into JSX's and Legacies, but I may just return to my roots and get an old Marshall and maybe have Jeff Seal do some work on it. I used to have an old JCM800 combo (mig50 owned it, too) but that thing had no setting between Off and Nuclear War in terms of volume.

[Neeradj]

Re: Old JCM800s

2205/2210 have diode clipping, 2203/2204 used tubes. My favorite is th 2203, but in all honesty I've never heard the 2204. I had the 2210 loaded with EHX tubes and I really didn't like it, but then again I was playing metal in my bedroom back then. I'm also going back to the basics and am considering a 2203 which I'll have loaded with 6550/KT88 tubes to lose the midscream and tighten things up. The 2203 just screams ballsy rock and takes pedals really well. A don't particularly care for the loudness, but it's sound is just bad to the bone.

[Rich_S]

Re: Old JCM800s

I voted for the 2204, but only because I don't think may people really need a 100 watter. However, I've owned both, and preferred the sound of the 2203; more thump to the sound.

I always thought that was just due to its extra reserve power and headroom, but I've recently learned that the output transformer makes a major difference between the 50- and 100-watters. Apparently, Marshall used a cheapy OT in the 50's, but didn't have a cheap alternate for the 100's. So, the 100's have a good OT, and the 50's don't. I've read reviews by people who have gotten major improvments in the tone of 2204's by changing to a high-quality OT, such as those made by Obsolete Electronincs (OEI).

The diode clipping question is easy - the dirty channel of the channel switchers has clipping diodes. The single channel amps do not have clipping diodes.

The best thing about the 2-channel amps is they're cheap ('cuz no one likes the diode clipping) and have a LOT of tube sockets and therefore make great mod platforms. I got a personal demonstration from Jeff Seal a couple weeks ago of his latest 2210 conversion, a full point-to-point-wired, blackface clean/JCM800-and-then-some dirty channel switcher. Great amp.

It should also be noted that you don't need to completely gut the amp to get major improvements. The diodes can be removed and the dirty channel 2203-ized without removing the PC board.

Good luck. If I needed a big amp, I'd be doing the same as you - buying a JCM800 instead of a modern amp. As it is, I'm happy with my little 13 Watter.

[JeffB]

Re: Old JCM800s

I voted 2204.

I love the sound of the 100 Watts (and even the diode clippers to a certain extent), but a single channel 50 watt (MV or NMV) is my thing when it comes to Marshalls. They break up a bit quicker, are a bit smoother, and a tad bit brighter. On a 800 series, all those are a plus in my book.

I still prefer the 1987(NMV) over the 800's though. You may look into grabbing one of them too. Bright and brash enough for metal, smooth and rich enough for more classic tones.

[The Golden Boy]

Re: Old JCM800s

I've got a JMP 2204, it's the cat's pajamas!

[kmcguitars]

Re: Old JCM800s

I've got a JMP 2204, it's the cat's pajamas!

Is there a difference in the circuit from a JMP2204 to a JCM2204 ?
I have a Laney PRO TUBE FIFTY (Pre-AOR) I've read it's a Knock off of
the Marshall 2204 circuit? Can't find a schematic for the laney. But looking
at the schematic for the 2204, It does read pretty close.
EDIT- I can't read some of the values on the laney's caps, And it
looks like some jr. tinker (other than me ) has been in there
messing around? So this is why I'm concidering a metroamps PTP
MV 2204 style board for this.

[Rich_S]

Re: Old JCM800s

I think early on, the JMP's had a different preamp configuration, 1 higher-gain preamp stage on the "HI" input, and 1 low-gain preamp stage for the "LO". Somewhere along the way, they were revised with some fancy switching on the input jacks so that the HI input used both preamp stages connected in series, and the LO used just one. This second configuration is what ended up evolving into the JCM series, adn is generally regarded as the better-sounding setup.

It's really confusing that all of these amps got called 2203 or 2204 (depending on their output stage), regardless of the input configuration or JMP/JCM cosmetics.

[chill]

Re: Old JCM800s

IIRC, the 800's had more filtering and different cap types than the JMP's, but otherwise the circuit is the same. Maybe different trannys as well, I do not know about that. There was a transition model in the JMP's which had hi/lo 2 inputs, parallel front end stages, and a mixer stage with a 330K plate R...IIRC that schemo is dated 1976. There were apparently not many of them made, and the JMP master/ 800 hi/lo jacking came out right after that.

kmc, does your Laney have 3 or 4 preamp tubes? And does it have 6 or 8 knobs on the front panel? 3 tubes, 6 knobs = pretty darn close to a 2204. 4 tubes, 6 knobs probably = the 800 preamp with an extra stage in front and behind. 4 tubes, 8 knobs = 800 preamp with extra stage in front and behind + boost switching

[ErikH]

Re: Old JCM800s

Is there a difference in the circuit from a JMP2204 to a JCM2204 ?
I have a Laney PRO TUBE FIFTY (Pre-AOR) I've read it's a Knock off of
the Marshall 2204 circuit? Can't find a schematic for the laney. But looking
at the schematic for the 2204, It does read pretty close.
EDIT- I can't read some of the values on the laney's caps, And it
looks like some jr. tinker (other than me ) has been in there
messing around? So this is why I'm concidering a metroamps PTP
MV 2204 style board for this.

The JMP 2203/2204 and JCM 2203/2204 are the same circuit aside from the input jack positioning. The only difference, from what I've learned, is the outside cosmetics of the enclosure.

I voted for the 2204. There's not much volume difference between 50 and 100 watts.

I've debated about having the diodes removed from my JCM900 MkIII but since it's a first year run of that model, and I don't see a lot of them out there anymore, I think I'm going to leave it alone. It sounds sweet as it is.

[Neeradj]

Re: Old JCM800s

I voted for the 2204. There's not much volume difference between 50 and 100 watts.

Actually like previously stated by Rich_S the difference isn't only volume wise, but they sound a little different as well. I haven't been able to compare the two, but according to people that have the 2203 sounds ballsier than the 2204.

[kmcguitars]

Re: Old JCM800s

IIRC, the 800's had more filtering and different cap types than the JMP's, but otherwise the circuit is the same. Maybe different trannys as well, I do not know about that. There was a transition model in the JMP's which had hi/lo 2 inputs, parallel front end stages, and a mixer stage with a 330K plate R...IIRC that schemo is dated 1976. There were apparently not many of them made, and the JMP master/ 800 hi/lo jacking came out right after that.

kmc, does your Laney have 3 or 4 preamp tubes? And does it have 6 or 8 knobs on the front panel? 3 tubes, 6 knobs = pretty darn close to a 2204. 4 tubes, 6 knobs probably = the 800 preamp with an extra stage in front and behind. 4 tubes, 8 knobs = 800 preamp with extra stage in front and behind + boost switching

6 Knobs 3 preamp tubes

[casblah]

Re: Old JCM800s

<---- Me likes my 2204. I've played thru 2203's, but I don't need that much volume for my house. JMP's are cool as well, IMO.

[Robert S.]

Re: Old JCM800s

I have an 84 2203 that I receintly had converted to EL34s and it's a screamer.

[Tom M]

Re: Old JCM800s

My guitarist runs an '82 JCM 2203 with matching 1960 slant cab. The thing is an absolute child-scaring, face tearing monster. I love it.

[Jeff Seal]

Re: Old JCM800s

Well, besides the obvious answer which would be "all of them".... I have to stick with my personal favorite.... '89 2210...(see the other "reverb" thread about some differences in the Ch. switchers) I love 2203's, but I really need a clean channel....

While the "later" 2210's have more gain than 2203's it does not automatically mean one is better than the other...... (I'm still wanting to play a gig with a Super Lead again!) The whole "diode distortion" aspect has been way "overblown" in the past, and my favorite amp does have them!

Rich_S pointed out some very valid points about the transformers....(but I gotta point out that "removing the diodes" only applies to the pre '86 versions, removing them from the later ones will yield a SF Twin MV "overdrive".....which isn't particularly "popular"..... since there is no cathode follower, only the positive aspect of the waveform "distorts")...

Although the cleans on the "later" ch. sw are not particularly great (no surprise here!), they are "workable" at best. Of course, I "cheated" and just installed a BF Fender clean in place of the original!

It's a tough call between the 800 Marshall's, but it's much harder to perform "Hotel California" with a 2203/4 than it is with the ch. sw. 800's... but then again the "control" is much greater with the single channels, when it comes to using the guitar controls...(both take some getting used to!)

Fwiw......

Jeff Seal