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

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.

I love that "Stop resisting" sticker! LOL

Stay til the end for some serious playing.

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.

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

Maybe Hendrix left it behind on Maui after filming Rainbow Bridge.....That'd be a sweet find!

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!

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.

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!

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.

Come for the amp repairs, stay for the playing 😎

One of the better Rare Vintage Marshall collects lives in Hawaii ,There are plenty of vintage Marshalls there.

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

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

I always love hearing it at the end. Nice playing. I know I learn a few things a long the way, still putting it all together. Thanks for the detailed look, quality stuff.

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

Great sounding amp, great playing! First time I ever skipped to the end of one of your videos and I don't regret it one bit! I'll check out the remainder later on this evening.

This is my lockdown therapy. Thank you Brad.

That was a great video! Good to see you putting the CE thru it's glorious paces! Well done man!

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

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.

Man...So good to the Ending👌Captivated me back to Specifics of Tone👏🤜👍Great Demo and Explanation

Check out Brad tearing it up on that obviously inspiring old Marshall. He's contorting and letting go with some fiery lead lines showing off his speed and dexterity. He's been possessed by the spirit in that amp from Hawaii. I've seen him play on some of his video and obviously he was good but he rose to the occasion of having that killer amp that's older than him or I. If that amp could talk. Oh wait, it was channeling its stories through Brad in the universal language of jamming on a guitar. Don't try to deny it Brad, you know you were feeling the mojo coming thru cuz of all the times I've seen you play this was special.

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.

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

That last 7 minutes ... so good I listened to it all twice, some several times, and part of it once at .25 speed. Nice one Brad. Terrific right hand.

NOTES: Here's a follow up video responding to some criticism of this video: kzfaq.info/get/bejne/kNh9grOVucmcd4U.html ALSO, the current owner contacted the former owner on the history of this amp at my behest. Turns out he bought the amp in LA, California before taking it with him to Hawaii. So if anyone in LA knows the history of this amp, please comment below!

Brad this is hands down your BEST video !!! keep it up comrad

This Amp was part of the secret to the ACDC tone.

Tube amps will Soon be a thing of the past if someone doesn't step. Up and start building all these tubes again. And ones working will go through the roof in value. Obviously. I appreciate your channel. The amps you document amd your a great teacher. Just doing what you do. In my opinion the thing about a great amp or an amp simulation. Is that every playing mistake shows. Can't hide behind the amp the amp. Is an instrument like the guitar and the fingers and touch amd mind behind the playing. And unfortunately I have played a few modelers with great tone that did just that to me. But im still a tube amp snob for sure.

Another great vid! You and this old amp are soul mates. Dig it

Thoroughly enjoyed. Thanks for bringing us along.

Always a joy watching you work!

Beautiful amp head.... complete classic... im very happy to see you doing amp repairs again... it sounds so goddam good..

Those old CE-24’s are so awesome. The amp sounds great, too.

That's some sweet playing Brad; little wonder that the rock world fell so in love with the "Marshall Sound."

Awesome video really dig how older amps were made

Beautiful history lesson here Brad!! What a cool amp! I actually got lucky at my last job and found a couple heating elements from commercial coffee brewers that are exactly 8 ohms each, so I can wire them at 16, 8, or 4 ohms depending on what I'm testing. They have nichrome coils inside, and when I pump enough watts into them, you can hear some sound coming from them 😁 Also, since they are heating elements I can use water as a heat sink if I need to do a long test. (I had an old solid state Peavey that was overheating, so I ran signal through it at a high level to test after I fixed it)

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.

Hi Brad, fantastic sounds your getting here, you know how to play and it sounds original and very different to any of the competition.

sounds good brad! thats a piece of history right there, and a very expensive one at that

Wow, great sounding amp and playing. I enjoy your vids still learn a lot from them. Thank you!

Your facial expressions toward the end there made me think you might keep that amp for a while for "further testing" 🤘

Killer sounding amp Brad. It's always fun to hear to go off on the guitar.

Best sounding amp ever designed.

The sound is magical. Wow!!

damn, I love seeing these videos evolve over time. Really enjoyable man.

Cool video, cool rare amp, absolutely fantastic playing as usual.

Now thats a PROPER cranked plexi tone!

Yet another great video!! Complete with great playing!!!

Great video! I can't help but think of all the music that thing has cranked out over the years!

man... hearing you grinding the plug hole gave me flashbacks to sitting in the dentist chair having teeth ground down for crowns... lol

Dang. Brad has some chops! Awesome vid man .

Fantastic video!!!! Thank You Brad!!!! Envious of the Beard.. Shaved mine off today and now every time I go outside and the wind hits my face it feels weird.. Feels good though.. Love your playing style.. I still say you would kill Beato in a showdown. You've got the Feel Bro.. Beato does not have the Mojo when he plays compared to you. Probably should not have even brought him up.. Just Popped into my mind after watching you play. I Traded my Marshall JVM 410C Combo today to a Guy for a Taylor 700 series Acoustic/Electric.. The JVM was a good Amp but had way to much going on for settings and channels ect. I like my JCM 2000 DSL 100 much more anyway.. Once again.. Thanks for the cool repair movie and fantastic playing

Sweet, love the classic gear!! Very cool video brother!! 😊🙌🏻🎸

Great to see more amp repair vids! Loved it

I used to attend college at the Hammersmith MO valve co in the mid seventies when I was trainee engineer with GEC telecommunications. Hammersmith by the way is central London.

Brilliant video again. I really like your guitar style. Great playing.

Think you had a ball at the end playing this thing ! Didn't know you could play fast like this , awesome video Brad and great amp !

best friday video in.a.long time.. love these amps..great tech and stellar guitar work there Brad...that feedback :)))

Nice one Brad. (I remember seeing Black Flag at the Christmas on Earth '81 Festival lol).

Dude, that amp wreaked of chocolatey tone goodness! 🇨🇦

hey BRAD what sup. man this time you got really technical and specific leaving no space for errors. the way you came up to measure the wattage shows that you are not just a average tech guy, you are more like the EVH technician level being able to see through past present and future. amazing. it would be really cool to have you make a video about your history in about becoming who you are right now.

Love the touch sensitivity of this amp. ...Amazing

I assembled a clone kit for someone. I loved it. It had one of the best cleans I've played, and I'm a Fender clean guy.

That sounds incredible, nice playing too!

Fantastic analysis as always.

DAMN, that's a sweet soundin' amp -- great job as always, Brad! Hope your neighbors enjoyed the test-drive. 🤣

Rock Star...throws the pick at his audience....he's in the zone!

What a cool amplifier, I would be honored just to be able to get to look at the inside of it and to work on it, but to actually play through it, how awesome is that!

Awesome thanks Brad

I bought a 1960 4x12 cab in Hawaii that was supposedly played through by Carlos Cavaso of Quiet Riot. It had belonged to a music rental company. They would rent equipment to bands on tour when they came to play concerts there. Very few acts brought their own stuff. They would tag the handles of the cabs with the name on them. This one still had the tag that said Carlos Cavaso. I sold it and all of my other Marshall gear before I left Hawaii.

Monster amp. Would love to have one like that.

came for the amp subbed for the playing. incredible!

Sounds like your playings getting alot better.nice sounds.

Your playing is better than it was ...always a good thing...

Id swear I'd heard Hendrix's spirit come out of that thing, sounds incredible!

Great content here Brad, thank you.

It is thought by many that this is the amp that Angus Young uses both in the studio and on tour for his solos. It's likely, though, the version he uses has a solid state rectifier. There are pictures out there of a couple in his rack; people often confuse it, thinking it's a JTM45. Informative video and joyful playing at the end. Thanks

No way would I pay that much, but apparently someone loved the sound enough. I learn a whole new thing besides playing from you. And yeah, you can play pretty good too.

I've been watching your videos for some time now and I must say your riffin on this one is impressive. If ever in the Detroit area we need to get together and jam!!!!

Thanks for the interesting video. I have seen and identical one that used to have a GZ34 but now has a solid-state rectifier. It looks as though something got very hot (the mains transformer) and vaporised varnish all over the inside. The extra resistor on the impedance selector is to lower the negative feedback fraction around the driver and output stage. Without this, this amp will oscillate at 100 kHz at full power - blowing any tweeters if you ever have any, but sometimes described as fizz, as you will have created a Class-D amplifier with lots of intermodulation! The original feedback resistor is 27K, but later models had 100K to lower the feedback, so I added 47 k and the amp was stable for all settings of the Presence control(with some effect of the treble, but that's not in the feedback loop). For those who like feedback theory, this is called gain compensation. An idea for setting up the bias from the mains power draw, could you turn off the Standby and see what the difference is? Most of the power difference will be going to the output tubes (minus maybe 6 mA x 440 V to the ECC83s = 2.64 W). Perhaps I skipped over you doing this? For the IEC connector - just mount it behind the original Bulgin hole, so you won't have to drill anything. I am sure this is why the IEC was designed as it is. Nice playing BTW. Cheers

Love it brother. Thanks. And nice playin' too!

Always great work and great guitar playing.👍

sounds great man!

DAAMN that thing sounds great .... awesome playing of course !

This is one of the best vids of yours. Especially the sound of your fingernails on that guitar, this amp sounds like an amp is supposed to.

You're amazing brother!

Pretty cool to see a PRS played on a vintage Marshall 🤘

Great idea on the AC cord. That will make the amp good for the next 50 years.

Awesome playin Brad!

That thing sounds sweet!!!

In the UK amps like this are converted to the EIC 3 pin kettle lead and have been for many years now . These are Bulgin sockets and we're OK for sometime but have nowhere near the insertion rate of the later 3 pin sockets . Replace this with a Bulging EIC for a couple of quid . Phone Marshall UK and ask them for a US 3 pin kettle lead and they will probably send one for nothing. I have done this many times here, but they may charge a few quid for shipping but it will be a stock lead that Marshall uses . It doesn't have as much effect on the value of the amp as you may expect . The EIC socket is 40mm between fixing centres and normally these are fitted straight into the hole and uses 2 3mm countersunk screws and nuts to hold the socket in . Keep the original parts of course .

It's fun to see someone who, not only knows how to fix an amp, but also play killer riffs. Cheers

Man nice documentary skills Chief!!

Love outros. Great amp, great content.

This is in my humble opinion a great example of the effects the volume control has over the wave forum and the sound of the the amp. That may not make sense. I probably not explaining it correctly. Well done all the same. Thank you!

Those capacitors there are "probably in the bias circuit". Yes, yes they are.

Brad you are one talented guy buddy awesome guitar licks love your method of playing and a hell of electronics wiz good show!