Yep, New Old Amp Day for me.
Acquired this old rocker over the weekend from another forum member:
It's a Marshall JMP 50. Some Googling of the serial number puts it as a 1969/1970 model.
Definitely far from perfect, but that's what intrigued me about it. It's been recovered at some point in its life - BADLY. There is some evidence of some work being done on the insides, the extent of which I am not 100% sure. Some of the pots are scratchy etc. But besides that, it's in working condition and it sounds AWESOME and to me, worth giving some TLC and trying to get it back as close to original specs, aesthetically and electronically as possible/practical.
The head has already been affectionately christened "Bad Boy Boogie", or TripleB for short. ?
He came with another old friend:
I bet this cab has a story to tell. It's been through the wars. Once again, it's also been recovered badly at some point, and needs a whole lot of work. It's slightly wider than my new 1960A cabinet, you can make out routed piping channels under the tolex/vinyl/whatever its covered in on the top. The grill cloth seems to have been painted black, and if you open the cab you can make out from the edges that the grill cloth used to be an off-white/creamy sort of colour. Not sure if it is original, but the cloth also seems to have a strange sort of weave pattern to it.
Here she is with the back open:
All 4 speakers are Celestion Greenbacks. The bottom right speaker has lost its green magnet cover thingy at some point. 3 of the 4 speakers have the following model number and date code on them:
Model T1281
Date Code 04FA
Google tells me these are Celestion G12H speakers, and they date back to 4 June 1968.
The bottom left speaker is different. It's a G12M according to the T1221 model code, and the BN6 code dates it to 6 Feb 1980.
When I plugged in a speaker cable to the cab and measured it's impedance, I got a figure of 3.9ohm. That would suggest that all 4 speakers are 16ohm, and all wired in parallel, rather than the 2xseries and the 2 series sets in parallel as my 1960a cab is wired.
Would there be any problem wiring the old cab in the same way to make it a 16ohm cabinet?
Busy preparing an extensive grocery list of items that marks the start of a long term project to restore both the amp and cabinet to their former glory.
