JCM800 Combo Versions

Jess 1971

Silver Supporting Member
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3,769
I've been looking at the JCM800 4104 2x12 combos, and I've seen what appear to be different configurations of what are advertised as the same amp. For example, both of these amps are listed as 4104 combos, but the inputs are different (horizontal and vertical). Are these functionally the same amp, or are there other differences?

Of the Marshall JCM800 2x12 combos, what should I be looking for? Is the 4104 generally well regarded?




 

LPMojoGL

Music Room Superstar
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9,070
On the 50 watt amps, 2204, 4010, 4104, the amps are mostly the same. Vertical inputs were made earlier and have chassis mounted pots. Horizontal inputs are later models and have the pots on the pcb. The combos have a cap across the mid pot that slightly changes the sound. Any good specimen of each model will sound fantastic and provide plenty of different tones. I just picked up a 4010, and love it. Probably more than my old JMP 2204. This one's been tweaked a bit.
The 4010 1x12 is heavier than I thought it would be. I can feel it when I'm carrying that amp to the Jeep. I'd probably get a cart with wheels if I were hauling around a 4104 on a regular basis, or put casters on it.
 
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Jess 1971

Silver Supporting Member
Messages
3,769
On the 50 watt amps, 2204, 4010, 4104, the amps are mostly the same. Vertical inputs were made earlier and have chassis mounted pots. Horizontal inputs are later models and have the pots on the pcb. The combos have a cap across the mid pot that slightly changes the sound. Any good specimen of each model will sound fantastic and provide plenty of different tones. I just picked up a 4010, and love it. Probably more than my old JMP 2204. This one's been tweaked a bit.
The 4010 1x12 is heavier than I thought it would be. I can feel it when I'm carrying that amp to the Jeep. I'd probably get a cart with wheels if I were hauling around a 4104 on a regular basis, or put casters on it.
Wow, this is awesome! Thank you! Incredibly helpful info.
 
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2,966
The vertical input models are generally more desirable, just because the pots aren't mounted directly to the board.

On 100w models, the horizontal input ones had less filtering on the poweramp as well, but I don't think there were any significant changes to the 50w models.

I have a 1980 4010, I love it. Very versatile, although I do prefer the sound of it through a 2x12 better.
 

BADHAK

Member
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8,868
I have a 79 JMP 2203, 80 JMP 2203, 82 JCM 2203, and a 82 4104 (vertical input with 12-65 speakers)

They are all basically the same circuit and are my fave amps ever. If I could keep just one it would probably be the 4104. I find it a tad more versatile in that the open back lends itself to more rock n roll, cleaner styles abit better and it does lower volume slightly better. Also, the open back is less directional so you hear the true sound even when you're standing virtually on top of the amp.

Of course if you're doing strictly hard rock or metal the 100 watt halfstacks are king, but the combo can get surprisingly close. Great amps.

The only negatives is the huge weight and the fact my 4104 (and another 82 4104 I had with Scumbacks )took me a while to dial in. My 2203's took seconds to get a great sound while those 4104's took me days to realise I had to keep the Mids really low otherwise the sound was too boxy.
 

Laurence

Gold Supporting Member
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8,319
I used to have a later ('88) 2X12. Simple, straight forward amp. Needs volume to get the goods.
 

Gridlock

Member
Messages
2,032
I owned a vertical input ‘82 4104 with G12-65’s, it sounded great at all settings. Super loud though.
 
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Bluesful

Silver Supporting Member
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38,943
Apparently there is a different cap value on the mid pot to give the combos more of the halfstack sound. Not sure how that works though.
That's interesting.

Not sure why Marshall wouldn't just take the 2204 and put it in a combo cab for a combo rather than messing with the circuit. Seems more efficient to just do that.
 

twotone

Member
Messages
3,980
My brother had the Canadian export version of the 50 watt 212 combo. It had EL34 tubes and metal toggle switches.
 

BADHAK

Member
Messages
8,868
That's interesting.

Not sure why Marshall wouldn't just take the 2204 and put it in a combo cab for a combo rather than messing with the circuit. Seems more efficient to just do that.
Yeah man, I'm not sure. I seem to be in the minority with my issue of having to keep the mids low, but in any case the end result is the same, its a great sounding amp
 

jhale

Senior Member
Messages
2,866
Go vertical input if possible because the horizontal eventually crap out and pots get scratchy and its all attached to pcb
 

Radius

Member
Messages
1,415
I have an 84' 4104 and it's been collecting dust for 8 years. I got it about 12 years ago and it was modded with a built in attenuator and an FX loop. I made the mistake of thinking I could be an amp tech and removed that stuff myself and did what I thought were some cool mods but it sounded better before I messed with it. I had every intention of having it restored but I found other rigs that suit me better. I still want to get it restored ......one of these days.
 

cardinal

Member
Messages
5,110
That's interesting.

Not sure why Marshall wouldn't just take the 2204 and put it in a combo cab for a combo rather than messing with the circuit. Seems more efficient to just do that.
Marshall simply added a capacitor across the mid pot, which just lets some low mids through if I'm understanding how it works. It would take seconds to remove, at which point the circuit is now identical to the 2204 head.

I have a 4010 and a few 2204s and honestly can't tell them apart if using the same cab. But my ears my well be shot.
 




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