Building a JCM800 (2204/50W)

GFirtha · 06-01-2009, 01:47 PM

Hello!
I'm about to build a JCM800 clone, but I have some missing info.
I can't find anything about the exact details on the output transformer, so any info about it would be useful.
I also wonder if anyone could give me some info on the chassis, eg. a blueprint would be great

, but also exact dimensions would be helpful.

Hardtailed · 06-08-2009, 12:45 AM

I suggest simply going with an OT designed specifically for a 50W Marshall. A bunch of companies make them, I used the Hammond 1750N. Primary impedance is 3200 ohms.

Typical chassis size for a 50W Marshall was something like 16.5X6.5

I used the medium-size chassis from turretboards.com which is 17.5" wide, except I went with the 8.0 deep one, which was a mistake (bigger chassis than necessary = longer wire runs)

RogerWilco99 · 06-17-2009, 04:34 AM

That Hammond 1750N is the transformer I just used (along with a 2204 turretboard from turretboards.com) for a rebuild of a trashed/stripped '80 2204 a friend of mine got from a guy in another band for $75.

All he got was the cabinet, the chassis and the stuff that is attached to the chassis front and back (switches and jacks, etc.). No circuit board, no trannies, no tubes. No pots, so all new pots, too.

I think it sounds great with those Hammond trannies in it.

We also put in all new tube sockets (ceramic) and tube keepers. I used cloth insulated wires on the internal wiring. This was my first complete rebuild of a "stock" amp back to OEM (well, except for trannies). I got most of the electronic parts from Mouser.com. I got the tube sockets and tubes from Joe Torres. I got the Marshall pots and knobs from tubesandmore.com. We re-used the cliff jacks, power, standby, impedance and voltage switches. The build only took a week after I got all the parts in.

Jack brought one of his 1960A 4x12 cabs over to test the amp when I was done. I think we may have annoyed the neighbors a bit. Jack's a great player, though, so hopefully we didn't annoy them too much...

I love this amp. I love the tone from those screaming EL34s. I think the only one I like better is the 2203 with four EL34s instead of just two.

Rock on, dudes!
Brucer

06-01-2009, 01:47 PM	#1
GFirtha Junior Member Join Date: Jun 2009 Posts: 2	Building a JCM800 (2204/50W) Hello! I'm about to build a JCM800 clone, but I have some missing info. I can't find anything about the exact details on the output transformer, so any info about it would be useful. I also wonder if anyone could give me some info on the chassis, eg. a blueprint would be great, but also exact dimensions would be helpful.

06-17-2009, 04:34 AM	#3
RogerWilco99 Member Join Date: Mar 2009 Location: Hoschton, GA (Atlanta) Posts: 43	That Hammond 1750N is the transformer I just used (along with a 2204 turretboard from turretboards.com) for a rebuild of a trashed/stripped '80 2204 a friend of mine got from a guy in another band for $75. All he got was the cabinet, the chassis and the stuff that is attached to the chassis front and back (switches and jacks, etc.). No circuit board, no trannies, no tubes. No pots, so all new pots, too. I think it sounds great with those Hammond trannies in it. We also put in all new tube sockets (ceramic) and tube keepers. I used cloth insulated wires on the internal wiring. This was my first complete rebuild of a "stock" amp back to OEM (well, except for trannies). I got most of the electronic parts from Mouser.com. I got the tube sockets and tubes from Joe Torres. I got the Marshall pots and knobs from tubesandmore.com. We re-used the cliff jacks, power, standby, impedance and voltage switches. The build only took a week after I got all the parts in. Jack brought one of his 1960A 4x12 cabs over to test the amp when I was done. I think we may have annoyed the neighbors a bit. Jack's a great player, though, so hopefully we didn't annoy them too much... I love this amp. I love the tone from those screaming EL34s. I think the only one I like better is the 2203 with four EL34s instead of just two. Rock on, dudes! Brucer Last edited by RogerWilco99; 06-17-2009 at 04:41 AM.

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06-08-2009, 12:45 AM	#2
Hardtailed Senior Member Join Date: Jan 2008 Location: Montreal, Canada Posts: 154	I suggest simply going with an OT designed specifically for a 50W Marshall. A bunch of companies make them, I used the Hammond 1750N. Primary impedance is 3200 ohms. Typical chassis size for a 50W Marshall was something like 16.5X6.5 I used the medium-size chassis from turretboards.com which is 17.5" wide, except I went with the 8.0 deep one, which was a mistake (bigger chassis than necessary = longer wire runs)

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