Metropoulos Forum

I am doing my layout for a 100W 2203 build and was looking at the different layout from SDM site and the Metroamp 2203 100 Watt Master Volume instructions and noticed the buss wires are different.

SDM has this on their layout:



link to SDM layout: http://home.comcast.net/~jbjdav26/2204/ ... l%20B+.JPG

And the Metroamp 2203 100 Watt Master Volume instructions has:



Why the difference and which is the correct one to go with? or am I just missing something here?

I do not know which one is more vintage correct (probably the SDM) , but electrically they are both the same. The difference is largely due to the way the positions of the 2.7k/.68uf and 10k v1 cathode elements are reversed. This defines which .022 is the output of the 1st stage, and which is the output of the 2nd stage. This is reversed between the two designs.

I just noticed on the Metroamp Instructions it says "Marshall model # 2203 JMP amps produced from 1976 until 1980", I wonder if the layout from SDM is from the JCM800 2203 '81–'84 instead of the original JMP model?

I'm sure George would know!

All the 2203 mastervolume heads are made on pcb, so if you want it vintage-correct get the pcb for this amp.