1966 JTM45/100

Ned B

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Here's one of my "biggies" that I have had since 1989. I haven't played it in few years so of course it needed to be brought up very slowly and the lightbulb too. Just needed the first cathode cap, otherwise all clear. Regulating the voltage to 115 I got to 565 volts as the heaters reached 6.3V. Back in the day that's about what the wall would have provided. This amp would have predated the Monterey amp of Jimi's. The way the PT was mounted with the extra mounting ring on top makes me think that the Drake 1204-43 hadn't been introduced too long before. The missing brass vents indicates they were out of them at the time, so they left it unfinished, though the slots were cut in the head cab. It also seems to be an early appearance of the square red pilot light. Chassis hole only just fits it whereas the RS light would have required a larger hole. The pointer knobs are vintage but probably not original, but maybe it could be possible that in Marshall-fashion they were out of knobs AND vents.
 

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Maggot Brain

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Wow man! My holy grail amp right there!

Once you get it up and running we'd love to hear it in action! Any chance you'd share how much you paid for it in '89? My neighbor was a gigging guitarist back in LA during the 70s-80s and said the early Marshalls could be had pretty cheap. The fad was to have a JCM800 or mod the piss out of the vintage SL and Plexis.
 

tomsvintage

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Here's one of my "biggies" that I have had since 1989. I haven't played it in few years so of course it needed to be brought up very slowly and the lightbulb too. Just needed the first cathode cap, otherwise all clear. Regulating the voltage to 115 I got to 565 volts as the heaters reached 6.3V. Back in the day that's about what the wall would have provided. This amp would have predated the Monterey amp of Jimi's. The way the PT was mounted with the extra mounting ring on top makes me think that the Drake 1204-43 hadn't been introduced too long before. The missing brass vents indicates they were out of them at the time, so they left it unfinished, though the slots were cut in the head cab. It also seems to be an early appearance of the square red pilot light. Chassis hole only just fits it whereas the RS light would have required a larger hole. The pointer knobs are vintage but probably not original, but maybe it could be possible that in Marshall-fashion they were out of knobs AND vents.
Ned B ~ Very cool and rare JTM45 / 100 Super Amplifier !!!! Congratulations on getting back in running shape :) Early version of the non block end chassis. Any shots of the tubes ? I would love to hear it too. Thanks for sharing :)
 

neikeel

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Thanks for sharing, beautiful amp
It has seen some serious heat and action.
I think V4 is a replacement and the screen resistors have been replaced as has the fuse holder (with some moving around of the wiring) some one has added tiny Welwyn resistors to ground - likely to help biasing.
So all things suggesting this was used in anger - exactly as it should be but kept pretty much to be sounding exactly as it did when it left the factory.
Is it running GEC KT66?
 

Ned B

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V4 tube socket changed for sure. Tubes are just Valve Arts for now. I will do some recording with it and see how it goes! Big with clean saturation.

I wonder if the previous owner, Clive Brown of Ripon could shed light on it's history.
 


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