Metropoulos Forum

The first JTM50's were really just JTM45's with EL34's and the appropriate output tranny for those tubes. They still kept the laydown mains, tube rectifier, and low filtering. The solid state rectifiers creeped in around '67 but tube recto amps still showed up into '68.......otherwise it was still basically the same JTM45-based circuit.
It was probably around late-'68 to '69 that 50's finally started getting the split cathode Lead vs. shared cathode Bass circuits with consistency. And you started seeing the standup mains tranny and top mounted filter caps in higher values.
I don't know if Yngwie prefers Lead or Bass spec, but last I knew he liked '72-era amps, so you know it will be the solid state rectifier and three top-mounted 50/50 filter cans, with a standup mains tranny.
I don't remember how late Brian Wallace's Marstran pictorial page goes, does it show 50-watters into '69? Great resource to visually check out how similar the early ones were to the '45's, and how slowly they evolved compared to the 100's.
I'm going to be building your Super Bass Dave....working on getting all the parts together........

I don't know yet if I will mimic the black JTM badge on the end. But I will be doing the two-rectifier, eight-filter-caps-on-the-board version like yours was (courtesy of Brian Wallace who gave up the secrets of wiring them -- you have to have the right power tranny wind for it to make sense!!!) Unfortunately I haven't found the block rectifiers like yours had (George hasn't had any luck either) so I'll have to do one of the various versions that were done with individual diodes.
I actually have a line on two power trannies for this project, so Black Flag Super Bass #2 is not out of the question.......we'll see how you like the look of #1.

My 1972 50 watt lead split cathoid.

Was that '72 a Canadian originally? Extra fuse, laydown mains........

I don't think so. The paper tag was removed so I don't have that. Brian Wallace thought it might be Swedish. It does have 16 ohm output. Somebody went to great effort to sell this amp as a 1969 so there are some weird issues wrong paper tag, possibly altered power cord connector the amp has bulgin socket but the chassis might have had a IEC connector. The chassis is stamped for 1972. English amps had lay down power transformer for some time after they stopped using them in the states.

What is the voltage on your plates 908ssp?

Didn't the Swedish version have an extra resistor coming off the mains that was required by law? I can't remember which Scandanavian country had the requirement but I remember being slightly intrigued when I saw it.

Long live the 50 watters!