In this video, what started out as the fairly straightforward re-capping of a tube-rectified late-60's Marshall JMP 50 amp with an NOS set of original "mustard" caps, turned into a real adventure when it was discovered that the circuit was not the Model 1987 Lead amp the owner thought he owned, but instead was a Model 1986 Bass amp. For reasons that are discussed in the video (at 10:26), it was decided to (reversibly) modify the circuit into the 1987 configuration by installing the set of 1987 "mustard" caps, and then compare the tone, before and after the conversion.
The video explains the rationale behind the conversion, shows a step-by-step (with schematics) explanation of each cap installed (at 12:25), and offers a direct side-by-side audio comparison of the 1986 and 1987 circuits (at 24:48).
In addition, there is a second feature video showing another conversion, in this case involving a chopped and channeled 1930 Ford coupe and three Stromberg 97 carburetors (at 37:14).
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