Inside a $10K Amp | Secrets of the 1967 Marshall JTM50 BLACK FLAG Plexi | REPAIR & DEMO
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- čas přidán 24. 02. 2021
- 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:
www.r-type.org/articles/art-14...
tubemaze.info/brimar-tubes-da...
www.gracesguide.co.uk/Marconi...
Guitar: PRS CE24
Cab: Fender w/ Eminence
Strap: Native Sons Wyatt
Mic: Electro-Voice 635A close
Mic 2: Shure Beta87A room
Music: www.reverbnation.com/electric...
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I love that "Stop resisting" sticker! LOL
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.
This is a master class in oscilloscope illustration on how an amp distorts a wave. Dirty pots and other stuff. Great job.
Thanks for the discussion. It inspired me to respond in a new video: czcams.com/video/ZrMOPdTc8GQ/video.html
Stay til the end for some serious playing.
worth it.
Ya hes a great guitar player to my ear....guess everybody's got they own taste. That charvel he plays is sweet
always
👍
Waw.
Come for the amp repairs, stay for the playing 😎
My dad has this amp head, one of the best in his studio and currently the flagship amp that he uses.
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.
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.
This is my lockdown therapy. Thank you Brad.
The fact that this amp was sent to you speaks volumes about your abilities
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
Nice history lesson on the Brimar tubes, you should do segments like that more often when applicable
that's the plan going forward. I've been testing the format in the last few amp vids, and I dig it. I think the audience likes it too. Gives me an excuse to research and geek out for a minute. ;)
@@TheGuitologist absolutely love it Brad. Keep it up.
@@TheGuitologist Hi Brad, absolutely, I really like the guitar/amp history lessons, and also to see the inside and learn a bit about how they function. I still don’t know what a rectifier tube actually does. I’ve learned a lot from your amp videos a while back. I also have some I might ask to have you service someday when driving home to see my family.
A rectifier tube changes the AC to DC. In some amplifiers, a rectifier bride circuit is used instead of a rectifier tube. Diodes are used in the circuit.
@@TheGuitologist sounded beautiful...
Now thats a PROPER cranked plexi tone!
Best sounding amp ever designed.
One of the better Rare Vintage Marshall collects lives in Hawaii ,There are plenty of vintage Marshalls there.
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.
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.
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!
oh ya? like who?
@@mattvdh Matt, Why don’t you go and see for yourself? The Hawaiian islands are full of music venues. From my hotel in Waikiki at Lewers and Kalia streets I could hear music coming from bars and restaurants every night. It’s not about WHO; it’s about WHAT. The islands are full of great music. Not personalities: just MUSIC.
@@jts3339 matt is correct, for you to question it simply shows your not as educated as you might think.. there are also a boat load of the rarest vintage Marshalls living there as i write this.
@@gatormcklusky5850 I stand corrected. Matt’s knowledge was obvious from his comment and I had no right to respond with my factual observations.
@@jts3339 sorry i didn't see anything factual i just seen somebody trying attack a guy to troll over an innocent comment, But you being the man with the knowledge had to set him straight. i can give names of great guitarist in Hawaii i can also prove there's one of the worlds rarest Marshall collection's is there also but you give me your factual statement first how about that.
That's some sweet playing Brad; little wonder that the rock world fell so in love with the "Marshall Sound."
Maybe Hendrix left it behind on Maui after filming Rainbow Bridge.....That'd be a sweet find!
@@electrofrying1685 maybe
That's what popped in my mind too.
that was my first thought when he mentioned Hawaii
@Spike Elwood Doubt it was Hendrix's amp.
@Spike Elwood There are five on stage in total and they should all be out there somewhere. Would like to know which Marshals he used, a bit of research should reveal the answer.
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.
Thoroughly enjoyed. Thanks for bringing us along.
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.
3 years late, but the JTMs aren’t usually what comes to mind when someone says plexi. They’re mostly referring to the JMP and Super Lead models. The JTM amps are certainly still plexis, but their sound is a kind of middle ground between the old Fender Tweed sound and the Marshall sound.
Man...So good to the Ending👌Captivated me back to Specifics of Tone👏🤜👍Great Demo and Explanation
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.
Man I LOVE hearing military stories like this. Thanks for the insight. I do know a ton of stuff was sent back from the Far East during Vietnam. Lots of fake Fender amps and such that are now collectible in their own right.
I knew a viet vet he told me he bought overseas the badass i think big hitachi home stereo speakers. Sent em home to his wife.
2 years later he was out. He came home and first thing he did was ask his wife " wheres the speakers I sent home"? "Hooked up to the stereo in the living room". He said wheres a screwdriver as his wife was trippin " what are you doing"? As he flipped em over on their baffle and took the screws out.
@@hadleymanmusic 👍 What a stashing story, H S McI! R 😎
@@hadleymanmusic so....what was concealed in the speakers? I know as a civilian contractor, we had a "queen bee" sight for updating KC 135s, there were a couple of other sights. We were told at a meeting, one of the sights found (while removing an antenna for replacement) a pretty big amount of heroin. We were shocked! Funny story, when work8ng for Lockheed in Atlanta, during mid 80s, a guy was found dead on some people's drive way, over 200 lbs of cocaine taped to his body(Too much weight for the parachute). Any way a few weeks later a bear in N GA found a seabag/duffle bag FULL of the stuff. He was uprooting trees etc! Had to be tranquilized!!! My friend said "Man if we'd found that, we could've made some $$$." To which his wife said "What? You 2 would've NEVER made it out of the woods!!" Lmao!(haven't seen those folks in over 30 years.)
There is a reverb listing for a bandmaster made by gabby but its a fender. Gabby is an overseas company from back in the 60s that made some of that stuff for the military and sailors
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
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.
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.
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!
Always a joy watching you work!
Those old CE-24’s are so awesome. The amp sounds great, too.
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.
Awesome video really dig how older amps were made
Glad to see you breaking out some amps and get back into your element on channel one Brad!
Absolutely man👍 love to watch him fix electronics he's a great teacher for sure
That was a great video! Good to see you putting the CE thru it's glorious paces! Well done man!
The sound is magical. Wow!!
Beautiful amp head.... complete classic... im very happy to see you doing amp repairs again... it sounds so goddam good..
Rock Star...throws the pick at his audience....he's in the zone!
sounds good brad!
thats a piece of history right there, and a very expensive one at that
This Amp was part of the secret to the ACDC tone.
Pretty sure during the Bon Scott years during the early albums they just used what they had - which was JMPs
Yes!
@@metalmulisha0143 yeah they used those to. Mainly for live but I think Malcolm used a JTM50 black flag in the studio I believe
man... hearing you grinding the plug hole gave me flashbacks to sitting in the dentist chair having teeth ground down for crowns... lol
Got the same association. Had a wisdom tooth surgically removed a couple of years ago. That wasn't an easy task. The dentist had to work his way down by drilling and breaking off pieces until he could finally extract the root remains and suture up the wound.
Me as well - dentist had to cut it up and literally break it apart and extract the pieces. At least Brad had the volume down on this part, but ARGH!!! you can still hear it.
@@pauldavis6356 wow i thought it was just ME...i had all 4 removed at once and they were ALL that way...it was years ago...44?.but you never forget it
Yet another great video!! Complete with great playing!!!
Id swear I'd heard Hendrix's spirit come out of that thing, sounds incredible!
Love the touch sensitivity of this amp. ...Amazing
Brad this is hands down your BEST video !!! keep it up comrad
That sounds incredible, nice playing too!
Another great vid! You and this old amp are soul mates. Dig it
Great video! I can't help but think of all the music that thing has cranked out over the years!
I know. On old amps like this, I can't help but wonder what recordings they might have played on. You just never know.
Your facial expressions toward the end there made me think you might keep that amp for a while for "further testing" 🤘
i would have quickly recorded a track with it before giving it back !
Great to see more amp repair vids! Loved it
Dang. Brad has some chops! Awesome vid man .
came for the amp subbed for the playing. incredible!
Killer sounding amp Brad. It's always fun to hear to go off on the guitar.
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)
damn, I love seeing these videos evolve over time. Really enjoyable man.
Hi Brad, fantastic sounds your getting here, you know how to play and it sounds original and very different to any of the competition.
Cool video, cool rare amp, absolutely fantastic playing as usual.
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.
Monster amp. Would love to have one like that.
NOTES: Here's a follow up video responding to some criticism of this video: czcams.com/video/ZrMOPdTc8GQ/video.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!
@Austin Martz i have the dvd and vinyl set. Also check out gabby amps from Vietnam. Theres a reverb listing for a fender bandmaster made by gabby
@@craigshewchuk9018 rỔ
As the owner of a Jtm45 from 1966, I was fascinated by this. I'm assuming the headphones at the end were for your protection. Mine is unusable. It's just too damn loud. I had kittens when I found out what these now fetch. I got mine in the late 70s for a princely £80 uk with a matching 4 x12 for the same price. Incidentally, the power input mod you did, I also had done on mine. Its quite a common fault according to the repair guy that did it for me.
Bought a old JMP Marshall that came from Hawaii
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.
Got some nice blackmore tones!!!
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!
Wow, great sounding amp and playing. I enjoy your vids still learn a lot from them. Thank you!
Sweet, love the classic gear!! Very cool video brother!! 😊🙌🏻🎸
Great idea on the AC cord. That will make the amp good for the next 50 years.
While he was messing with the old connector I was thinking to myself, "Man, he should just put in an IEC and be done with it!" Sometimes I get it right. LOL
Brilliant video again. I really like your guitar style. Great playing.
Fantastic analysis as always.
Nice one Brad. (I remember seeing Black Flag at the Christmas on Earth '81 Festival lol).
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.
JM was a fender clean guy as well 😉
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
DAAMN that thing sounds great .... awesome playing of course !
Pretty cool to see a PRS played on a vintage Marshall 🤘
You're amazing brother!
DAMN, that's a sweet soundin' amp -- great job as always, Brad! Hope your neighbors enjoyed the test-drive. 🤣
Awesome thanks Brad
sounds great man!
It's fun to see someone who, not only knows how to fix an amp, but also play killer riffs. Cheers
We are a dying breed who barely lived.
@@TheGuitologist lol awesome!
Sounds like your playings getting alot better.nice sounds.
That thing sounds sweet!!!
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.
Your playing is better than it was ...always a good thing...
You still have the best damn intros
Love it brother. Thanks. And nice playin' too!
Awesome playin Brad!
Great content here Brad, thank you.
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 !
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.
@@electrofrying1685 you really are electrifying hahaha. The truth is I’m barely starting myself into electronics so I’m easy to impress at this point. Everything you said sounds awesome but makes very little sense to me. I’m not trying to annoy you just being very honest. So I believe you when you say that there is still room for mistakes but you must admit BRAD did a nice video, in spite of the gaps he could have left. Anyways have good week. Hope to see you in another episode and I’ll check your videos if you don’t mind.
Man nice documentary skills Chief!!
Ahhhh, the sounds of my youth.. Most excellent.
Always great work and great guitar playing.👍
Dude, that amp wreaked of chocolatey tone goodness!
🇨🇦
I had a similar amp. Tube rectified steel chassis EL34 made in ‘67 Glorious sounding amplifier. Serial number was within 100
best friday video in.a.long time.. love these amps..great tech and stellar guitar work there Brad...that feedback :)))
Awesome bench🎸
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
Dude you are a killer player
Great finish. Wow.
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.
Love outros.
Great amp, great content.