Tell Me About JCM800 4010.

[Wilko]

This one is definitely a single channel. I'm assuming you have to crank the crap out of it for it to give up the goods.

These are master volume amps. No need to crank it.

I lucked out and got my chopped up head for 325.00! :##

 

[riefil]

These are master volume amps. No need to crank it.

I lucked out and got my chopped up head for 325.00! :##

Nice. That kind of thing doesn't happen to me.

 

[FretsAlot]

Wilko,

I was studying the circuit diagrams you supplied above. The top preamp circuit (prior to the phase inverter) is slightly different in a couple places as compared to the one below it, but I didn't see a notation about it being for the 4010 - did I miss it, on the diagram?

Also, the lower circuit says that it is for the 2103, 2104, 2203 & 2204. The 2103 (100w) & 2104 (50w) were the 2x12 MV combo model numbers for the final years of the 'JMP' models. From my reading, I'm to understand that when Marshall left the JMP years and went into the JCM years, they adjusted/revamped some of the model numbers. So the 2103 became the 4103, and the 2104 became the 4104. Seems the leading '4' may have been Marshall ways of designating a combo (thinking aloud). I believe '81 was the first year a 1x12 combo was available and also happened to be the first official(?) year of the JCM's.

Edit: the second diagram is dated April 24, 1981, so early in the JCM span, perhaps Marshall hadn't quite adopted the new combo model numbering convention at the time the diagram was made.

Fretsalot/Scott

 

[Wilko]

I found a schematic for both amps and overlayed them. The ONLY difference is that cap on the middle tone control.

Circuit is the same. Same amp, no "vastly different topography". That's what I was getting at.

If the OP wants to know if an early 4010 is like a 2204, it is the same amp, so it sounds the same.

There are posts in the thread that say otherwise, with no proof. I like to "show my work". :##

 

[JR.Deluxe]

All I can tell you is I have owned and played 2203s and 2204s and 4010s. They may have the same circuit schematics online but they don't sound the same. You used to get 4010s for $400 all day long when 2204s were $800. There was a reason and I found out the hard way. The 4010 aren't totally useless just disappointing if you think your are getting an undiscovered secret 2204 .Go ahead and buy one , I don't care either way. I'm just telling you my experience.

 

[Wilko]

based on what?

I own both and they are the same. They sound the same. There is no reason they wouldn't. They certainly are a "secret 2204" and they are a bargain. Oh, but the chassis is a little shorter on the 2x12 and lot shorter on the 1x12la


Here's the back end schematics overlayed showing NO DIFFERENCE. The only difference is a tiny cap on the mid control. One snip away from a 2204 (or just use the mid control).

 

[demundo]

the 1976 2204 does not have a cascaded low and hi input. it is a different preamp topology and sounds different than the later cascaded preamp of the 4010, and later 2204 if you have the history of marshall first ed it is on page 203. yes the later 4010 and 2204 share the same preamp design.

 

[Wilko]

the 1976 2204 does not have a cascaded low and hi input. it is a different preamp topology and sounds different than the later cascaded preamp of the 4010, and later 2204 if you have the history of marshall first ed it is on page 203. yes the later 4010 and 2204 share the same preamp design.

Oh, you're talkin' a JMP 2204 to a JCM 800 (what we're talking about).

Even those are closer than a glimpse of the schematic will tell you. The layout of the Schematic makes it look a lot more different than they really are specially as the 1976 drawing doesn't actually have the V1 drawn split apart, though it is still using each half of V1 for low and Hi inputs.


So, to try and clear it up... A JCM800 4010 is the same amp as a JCM800 2204 except for 1 cap added to the mid control.

Compared to the JMP Master Volume 2204 there are a bunch of value changes and some other differences that were changed when the JCM800 style started that make the JCM more "gainy".

 

[FretsAlot]

Wilko,

Thanks for doing the schematic overlay to expose the added cap on the mid pot - nice visual proof. I'd read about it in prior research, but hadn't yet taken it to be fact. There it is...

to be taken with a grain of salt: I don't have any detailed knowledge committed to memory, but I have remembered reading that the '76, '77, and... '78?... JMP MV amp circuits were changing during those years until Marshall actually seemed to settle around '78? '79? on the core schematic most of us know those amps by.

Fretsalot/Scott

 

[Wilko]

no doubt that the 2204 model changed from JMP to JCM.

I wouldn't claim otherwise.

The OP asked about a JCM800 4010.

The combo version of either amp is virtually the same as the head versions JMP or JCM. I have combo shassis for both of these right now, though my JMP is torn apart right now 'til I can get it back to stock.

 

[FretsAlot]

no doubt that the 2204 model changed from JMP to JCM.

I wouldn't claim otherwise.

The OP asked about a JCM800 4010.

Sorry, I wasn't suggesting otherwise, just throwing out some more info for those who were commenting about the JMP's and not the JCM's. I'm in agreement with ya... :salude

 

[Wilko]

no worries. Just chatting, trying to clear it up some.

what have we learned? :hmm

JCM800 4010/4104 is the same as a JCM800 2204 except for a cap on the mid control (that can be clipped).

That there are combo versions of the "head" amps that are a relative bargain, and they can be made to sound just like the head versions (if you know which amp you want/bought). :dude:

 

[Triburst]

Just curious, Wilco. How close is my JMP 2204 to these 800's?:hmm

 

[ant_riv]

This hasn't been discussed yet, but ....

I have an '81 4104 with vertical inputs and an '83 with horizontal inputs. There are some who claim the vertical input versions sound better than the horizontal versions, but they are nearly identical to my ear. The circuit is essentially the same for the 50w versions.

From what I understand, the 100w version (2203 or 4103) horizontal/vertical does sound different, as there was a change to the circuit.

 

[CoyotesGator]

My 4010 dated 17-8-82 is a wicked little beast and sounds good through its G12-65 and great through a proper 4x12 cabinet. ITT caps and Drake transformers in mine. I would think an original Super Mint example should be $1100 to $1000 in my area. All were 6550 output tubes in the U.S.

Edit

Well used with unknown tubes/issues $600? I'm a long way from NY though

 

[Gold Tone]

Horizontal vs vertical input change at Marshall is not a tone related drop in quality but rather build. Vertical inputs were hard wired with flying leads while horizontal are mounted directly to PC board leaving board and connection vulnerable to cracking. Likewise pots changed to PC mount and later tube sockets.

 

[riefil]

So I got to try it yesterday. Seems like more issues than I originally noticed. Every knob was broken, likely due to a face-first fall. Other evidence of this was the deep divots on the front edge of the cab. I plugged in anyway...you never know. Sounded pretty decent until I started increasing the pre gain volume....very pronounced hum. Probably just a tube. The low input however was pretty awful. Almost no gain whatsoever, volume drop was very dramatic. I would say it was pretty useless. Overall I was pretty disappointed. At $900 no way. I started chatting with the sales dude and he made it clear that they will not budge on the price. Needless to say I am not the owner of a JCM800 4010.

Phil

BTW serial number from what I could make out(didn't have my glasses) was 07987P

 

[Purgasound]

Don't mean to resurrect a zombie thread but I think it's important to correct information that's not well known. In regards to the 2203 being different that a 4103, I'm staring at a 4103 from '84 on my bench right now with a 220K resistor in parallel with a 220K mid potentiometer. That's essentially made it a 110K mid pot versus the 2203/2204 value of 22K. These are stock components and I have not seen the 4103 specific schematic that shows this part.

 

[Purgasound]

oops double post

 

[Purgasound]

C5 is missing, the bright cap across the preamp volume pot
C8 is missing, part of the treble peaking circuit across a 470K resistor
the tone slope resistor is 56K ( have also seen this on other 2203/2204's before)
C13 is not present on 2203/2204 circuits and it's not even on the schematic. This is a 4700pF cap bleeding more treble to ground in the tone stack. This is used in conjunction with a "LK1" link that's tied to the mid control. LK1 is not fitted on the 2203/2204 circuit either
Also the treble cap in the tone stack is 220pF instead of 470pF

I'm noticing these differences as I'm doing work on it. It didn't sound good at all. These combos are VERY different sounding from the head counterparts because of this. Very woofy and muddy with no bite.

I have been putting things back to the typical 2203/2204 preamp spec and it's sounding a lot better.