Inside a $10K Amp | Secrets of the 1967 Marshall JTM50 BLACK FLAG Plexi | REPAIR & DEMO

In this video, we'll troubleshoot, repair, and demonstrate a RARE 1967 Marshall JTM-50 Plexi head. This amp was only made in this configuration for about ONE YEAR, so there are that many around. We may have to do some drilling / grinding on the chassis to accommodate an IEC replacement for the original Bulgin pignose power socket.
SOURCES:

Guitar: PRS CE24
Cab: Fender w/ Eminence
Strap: Native Sons Wyatt
Mic: Electro-Voice 635A close
Mic 2: Shure Beta87A room

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[BillHertzing]

This is a master class in oscilloscope illustration on how an amp distorts a wave. Dirty pots and other stuff. Great job.

[charvel]

Face melted! Love that you’re back doing amp repair vids, could tell you enjoyed playing it. I’ve learned so much over the years, thanks from the land down under.

[IanThatMetalBassist]

Nice history lesson on the Brimar tubes, you should do segments like that more often when applicable

[geoffreyharwood]

Hello i'm from the UK...just found your channel...Loving the irony of..."It takes an American to explain how a British amp works..." looking forward to discovering all your previous amp repair vids...Your very articulate when explaining the relationships between the variac, oscillator, voltage meters, and how all the wiring relates to the schematic..."am loving the learning..."...Thanks for the inspiration...and more power to you.

[rogerfurer]

I grew up in Honolulu. I bought a Marshall 4x10 combo amp in a pawnshop in Hollywood in the late 70s. The chassis inspection sticker was dated 1967. I traded it to a friend of mine for an early 70s 50W head and 4x12 cabinet which came with me to Florida when I moved. My friend was one of 2 Marshall collectors I knew in Honolulu. Both rented out rigs for concerts and I used his 100W heads and double stacked 4x12 cabinets when I played in the arena there in the early 80s. I also heard of another Marshall collector there, so finding an old Marshall in Hawaii is not so far fetched. My friend died in 2019 and I don't know what happened to his collection.

[gamepad]

My dad has this amp head, one of the best in his studio and currently the flagship amp that he uses.

[BockwinkleB]

Stay til the end for some serious playing.

[misterknightowlandco]

Dude, we need more playing videos from you. Your too damn good at it. Love watching the fixing videos don’t get me wrong, but you should put up a few more performance vids up once in awhile. Cheers

[roberteffler]

The fact that this amp was sent to you speaks volumes about your abilities

[MC-eeey]

This is my lockdown therapy. Thank you Brad.

[jts]

Brad, Hawaii is full of great guitarists! I’ve been there 8 times and the bars and restaurants have some of the best and most dedicated players I’ve seen anywhere. The amp probably WAS NOT left by some traveling mainland musician, but more likely belonged to a local who had it all these years. Great music thrives in Hawaii!

[richard]

Love the JTM circuits. They’ll roll off to beautiful cleans all the way up to pure AC/DC tone. Thanks for posting this repair.

[nohandleforme....]

I love that "Stop resisting" sticker! LOL

[jeffcashio]

Hey Brad I lived in Hawaii for 12 years and I collected jtm 45s
Along with Kurt Weigert and Tom hinson
We also played together in a band called the jtm 45s

[dulam]

I swear that when you opened it up that I could smell the unique smell of amplifier circuits. Also, You don't know how refreshing it was to see someone with proper soldering technique.

[kedocom]

If I was the owner and believed it to be a $10k amp, I would have paid extra for the original style plug one fix for plugs like that is to apply solder on the male ends and shape it to enlarge the posts Cool vid Brad!

[MrOzzy]

Come for the amp repairs, stay for the playing 😎

[bluesingmusic]

Lots of military there Brad. Back in the mid 70s when I was in, there guys I knew who had rigs, you wouldn't believe. Of course going overseas one could get MONSTER equipment (stereos, instruments, amps, etc) in the PX/BX with no taxes, import tariffs, etc, etc.(Never saw Marshall equipment in the Base exchanges though). A friend bought a Strat in 1982, when I worked in Korea (DoD contractor, but we had full access to everything on base), he picked it up for around half of what cost here. When I was in the military, I saw guys with Nakamichi(spelling?)stereos. One guy bought 1 of their under dash car cassette decks at Subic Bay BX, it cost $1200 there. I can't imagine what they cost at regular retail.(I hadn't heard of them, but I was informed, they were pretty much the BEST stereo equip on the planet. Any way, in the 60s & early 70s you could pick up old used Fender tweeds, etc for less than $50. Any way, just thought I'd throw that in, I actually knew sailors in mid 70s that had full Marshall stacks, & other mythical equipment.(I know I'm showing my age, but hey I'll admit to being "legal age" as my mom used to say) Hope you're doing well.

[gearhead]

Glad to see you breaking out some amps and get back into your element on channel one Brad!

[breakburrito]

So this is what an old Marshall plexi sounds like. I've always been more into Fenders, but that Marshall can sing! I get it now.