Comments and Corrections: 1.) At 3:12 I meant to say built with "British" parts, not Fender parts. 2.) At 11:15 The transformers are all built by Drake and are correct and original for the amp. They are labeled with part numbers, not EIA numbers. 3.) At 13:30 This is one of the original Hunt's electrolytic caps, disconnected and left in place for appearance. 4.) The schematic used in the comparison is for a later model JMP (Model 2204), but it matches the demo amp fairly well. The correct schematic is for a model 1987. 5.) At 16:13 I meant to say trim "pot" not trim "cap".
Doug, love your videos man. I'm in the way straight to my first build but I have some troubles with the power transformer design and calculations. Can I ask you a few things? I need some advice and knowledge
Chris, have you watched the videos I've posted that deal specifically with that topic? They contain virtually all I know on the subject and are readily available. If you still need help, I can try to answer your questions here or on my FB page: Uncle Doug's Vintage Amps.
Yes Doug, and the series about that topic was as great as all the others. In fact, it's because of your videos that I feel encouraged to learn and try my first 5E1. But here is my doubt. I saw that some more actual amps like the Orange OR15, based on the Tiny Terror, have a way to reduce from 15W to 7W by taking the half voltage from the secondary of the power transformer. The well known original transformer for 5E1 is 325-0-325 and I want to know if I can make some sort of 325-180-0-180-325 for the selectable voltage to the rectifier tube and how to make it, what type of things must be considered. Also I want to add others changes to the original schematic such as gain pot, presence pot, shape (Orange style tone), and a 3 selector switch to ad by pass cap on both sides of ECC83 which is the only valve I've found at my local supplier
@@christiancosta7997 It's plausable to use a transformer with different voltages, although you'd need to be aware of possible bias changes. What you're describing is basically the same as "browning" the amp with a variac... cutting down all of its voltage a bit. Take a look at a schematic from the ORIGINAL Vox Night Train, not the G2. They used a Triode mode on the EL84s to cut volume. www.prowessamplifiers.com/schematics/Vox/Night_Train_Updated.html
Just saw this. I was thinking the same on the schematic. They had a JMP 50W 1987U model that had tremolo, from what I can see online. No idea what exact model number this is. Anyone know? The cool thing about this one is you can jumper those inputs and blend the two channels in parallel. Talk about overdrive!
Great video again Doug. The amp really sounds great. The most remarkable feature of this amp is it's managed to survive for 52years without getting any white paint splatter on the top of it. Keep posting the video's, you put smiles on a lot of people's faces. Thank you.
Ollie is such a beautiful cat. That being said, I would give my left nut for a Marshall that clean. I was disappointed to see that someone had removed the original Mustard caps. FWIW the original JTM 45/Bluesbreaker amps were exact copies of the Bassman circuit and used KT-66 tubes. Those tube along with the Radiospares output transformers gave the early amps their unique tone. The tube rectifier tells me that this amp is a transition model right before they went to SS rectification. Another great vid, thanks Uncle Doug.
I have spent the last 4 months watching Uncle Doug videos. They are amazing and his humour is my cup of tea!! Very informative and to the point. Hope there are lots more to come!!
I own a 1970 JMP 50 watt head that I purchased new in 1970! It was my first serious amp, and I paid $595 for it with the 8x10 speaker cabinet which I sold just a few years later. It is in ‘near-museum’ condition and at first glance looks identical to this beauty. Mine, however, has an aluminum front panel and solid state rectifier, which is actually my preference sonically. I have replaced all electrolytics and set bias each time I’ve replaced power tubes, aiming for a just slightly warm 38mA. I’m not worried about using EL34s as I’ve replaced them several times. I’ve even kept the original Mullard EL34s but one is shot. What’s really important is, it sounds glorious! I have recently decided to never sell it. The tolex is in even better shape than this beautiful plexi’s. I will use it until I die. It’s going in my will to my daughter. She doesn’t play, but maybe it will buy her a car one day.
Uncle Doug Thanks Doug. Sorry for coopting your comments section. I felt like I was looking at a twin, couldn’t help it. I really enjoy your videos and would like to have contact info to recommend you to customers. I only work on my own stuff but from what I’ve seen, I would send anyone to you. I don’t know how to pm someone on TH-cam. Any ideas?
I'm real selective on what I work on, Peter. It would have to be a vintage tube amp, the older the better. If a customer wants more info, they can contact me here or on my FB page, Uncle Doug's Vintage Amps.
Uncle Doug But of course, selective, I picked up on that right away. Thanks for the info. Most of my customers are very choosy, and I would just refer them to you directly. I’m sorry I’m not on FB, but you can check me at www.artisanmobile.com if you’re interested.
Another fantastic video for us ampoholics, Uncle Doug. That is one killer Marshall! Thank you for putting the time and effort into these videos. I'm sure it is not easy and very time consuming. I always look forward to your videos & appreciate them very much! Keep them coming!
I remember the days in dublin( in the 80s) that you pick up one of these things for 150bucks a pop, in fact i was walking by a music store one day and they were tidying the shop they had a skip outside (large waste disposal bin)and there on top was a marshall 50watt head in good condition for its age, i asked they guys why they were tossing the thing out and they said it had a blown transformer , needless to say it came home on the bus with me. replaced transformer and used it for 10 years then sold it for 1000bucks just when the vintage bullshit started ...true story Doug...PS love the posts
@@UncleDoug Persactly. I bought 2 of these in the mid-80s when nobody wanted old single-channel amps with no FX. Needless to say they're not for sale now. I love playing through them.
Thanks Uncle Doug for this very comprehensive review and curcuit comparison. I've learnt more about valve circuit design from you than any of the tutors I had when I did my trade 35 years ago. Your passion is obvious and appreciated!
Thooly Doo sorry I am late to the party. I appreciate the awesomeness of the 4 x 12 cab, but the cab itself has some great history, and Pete T. was involved. Seems the Marshal 50W amps were typically played through two 2x12 Bassman cabs (oh, the horror). Jim promptly designed and sold the 1960 4x12. It was his 100W amps that gave birth to the “stack”.
I nearly teared up watching this, it reminds me of my old Marshall amp, that I traded-in in the 80's, stupidly. The biggest problem with them was 1) Don't loose the power cord!!!!! and 2) the selectors at the back could drop out during transport, everyone used to tape them up. Thanks Uncle Doug great video again.
Nice video walk through of a classic amp Doug. I've a super clean 1966 gold script JTM45 MKII Plexi head (30w RMS) that I've owned and used since around 1976 with GEC KT66's, Mazda GZ34, ally chassis and rare cream backplate with single speaker out. Wish you could see/hear it, as you clearly really appreciate the quality design and manufacture that Ken Bran and Co put into these early point to point modded bassman beauties for Jim Marshall to market.
@@UncleDoug Thanks Doug. I was 18 when I picked it up for £90 ... just seen as a 10yr old used amp back then ... how times change. Had a couple of other good amps over the years but never been tempted to part with this one.
After your first successful Marshall build, if you want to start making a lot of money, I suggest you run a few well placed advertisements asking for trainees - people interested in building guitar amps. Hire 6 for starters. Then you train them and supervise the construction of new Marshall Clone amplifiers. Then offer them for sale. If you do this in a legal way I am sure you will absolutely end up with more money than you need. You might even be doing the world a service by introducing new guitar amplifiers under your personal brand name and hopefully at an affordable price. -Peter P.S. Jim Marshall hired a tech right out of school (before he finished school) doubled his salary and had him have a go at making the kind of amp being asked for my the guitar payers visiting his shop. The technician is responsible for the modifications, Jim used his "ear" to say when it was right and "good enough". He sent a few of them out as pre-production units and people wanted to buy them after using them. The future was right there in the making and he went into production.Mr. Marshall did not do any design, lets be clear on that. The student tech is 100% responsible for all the electrical design modifications which were based upon Jim's blessing of the sound. So all in all Mr. Marshall actually was involved as it was he who knew what tone/sound was needed. The tech was clueless about music but he could solder, sketch out schematics and know a little bit about how to change the component values to achieve a change in tone. I am not 100% sure of what I just wrote because I was not there! I read this here on TH-cam a couple of years ago. It makes sense as why would a drummer ever have a need to modify a guitar amplifier components? Why did he hire a electric tech to do the work, if he could do it himself? The answer is he could not he needed the skills of a specialist, an electrical technician who was familiar with components that go into making a guitar amplifier. You "Uncle Dough" have that knowledge and I hope you take us up on the idea of building your own Marshall amp and then take me up on my suggestion to train a a small workforce and open up a small amplifier shop where you live. You have so many TH-cam followers I think you already have a huge customer base. I know you are not interested in wealth. Your wealth is knowledge. But, I would love to purchase a Marshall type amp from you. Think about the future of all the young people who you provide training and employment. That might be a "Legacy" that you never considered. Maybe you could even start a tech school for building guitar amps. You could retire (again) and just watch it grow. Your knowledge of electronics will be shared and will flourish. That's another "Legacy". Uncle Doug's knowledge get's passed on and lives on!
Very nice, I especially enjoyed the component by component circuit comparison with detailed explanation. The cats are sounding tighter every time they play, I really enjoyed the opening song. Thanks for sharing.
Good day to you Uncle bob. This one was special for me. I am 54 and was a fender guy first. Swore off marshalls cause everyone else had them. Then it happened ......I plugged into a guys garage rig of 7 rows of full stacks with two heads on each one. A bit of a collector. Anyways that was it for me. Wasnt soon after that that i got a 68 baby box non export plexi. Its gone now but i replaced it with a metropoulos super lead plexi clone. Wow. I learned that billy squire lick early on and its a real pleasure to hear you do it. Thanks for the great insights. Loved the comparison of the two circuts. Now doesnt the bright fender input drop to 34k because of the switching jacks throwing 2 68s in parallel. This is something i would love to hear explained.
Clapton used one in the Yardbirds, Jeff Beck prefers a 50 watt Marshsall of that design, and Peter Green used that same exact model to record The Supernatural.
In the 80s I was in a rock band where the lead guitarist had one of these (but ss rectifier), a '61 LP Junior and an MXR Distortion+ and the rhythm guitarist had a 100W SupaLead and an Explorer. It was aural heaven, and complete carnage. Sorry, didn't hear that last remark. Me? Thunderbird into a DR103. In England in the 80s they were giving these amps away (I bought a mint DR103 for £100 - it's still mint and worth a metric shitonne more now. Even got the bloody Bulgin plug/socket, a source of worry. If that lead goes missing at a gig...) . Yes, but the tinnitus is worse in the left ear. Since they were all 4 input amps you could jumper them all together. Speakers were 2x15 H&H, Hiwatt 4x12 (Fanes) 2 Marshall 4x12 and a Marshall 2x12, many of them original 25W speakers. It was EPIC! In fact epic did not do it justice. BIBLICAL. Thursday? So am I, let's all have a cup of tea. Yeah, just had to tell you. p.s. the idiot guitarists sold all that gear (I nearly cried). I still enjoy mine.
Thank you for another outstanding and well presented explanation of the workings of these two amplifiers. Your channel never ceases to be a wealth of knowledge and understanding for us mere mortals who never could have aspired to this level of comprehension of this historic and beautiful old world technology. I hope the joy you have shared with us over the years is returned to you 10 fold.
This video, maybe the first 5 minutes, made me spend like 6+ hours searching and discovering Marshall series and model name codes history, completely ignoring everything from lunch to whatnot. Now I can finally say I have some idea of where the series and units get their codenames and how they wrap in the evolution of different series. I can happily say that in the beginning it almost made sense, got very quickly out of hand and then around JCM900 it started making better sense once again. With little quirks that make it inconsistent. They ended up mixing everything up with MR modern cabinet series where they could've used the existing codenaming to preserve some connection. Now everything is just 1960 or 1936. One of the things that has made the least sense was the 1922 vs 1936 cabinet. Same 2x12" cabinet, just slightly smaller dimensions in 1922. But now it makes sense, 1959 (whatever series it was, JTM, JMP, JCM, reissues) was always 100 W 'Super Lead' head (first introduced when JTM100 came out), while 1987 was the same in 50 W, but only 'Lead' (except the first entry, JTM45 was naturally only 45 W). The main guitar heads of Marshall through the history. 2203 was the 100 W 'Master Volume Lead' and 2204 was the 50 W version of it (since JMP to JCM, essentially JCM were the same products, but in the 80's). Then there was also 2205 and 2210 which were 'Split Channel Reverbs' in 50 and 100 W (reversed this time, but you can see the code actually serving some function for once), which to my understanding were the first to include channel switching (FINALLY) and also reverb, happy days. There might have been changes throughout the different series (JTM, JMP, JCM) to those different Lead heads in sound and some might be more favourable than others (JTM45 being 5881->KT66, JTM50 series starting to phase out GZ34, JTM100 being solid state rectifier and going from KT66 to EL34. US distributor swapped from EL34 to 6550 in JMP series for busted tubes over transport and people thinking theirs 6550 amps sounded worse, but some liked the increased high frequencies). It seems like the early JMP 18 W combos had EZ81 rectifier in 1965 (the prototypes of JMP series) and were replaced by 20 W models in 1967, which had solid state rectifiers. However, 1967 also being the year of transition from JTM to JMP and this amp being 1967 JMP, it's very possible that they were still using the last stock of GZ34 rectifiers in JTM 1987 models and this is a very, very early JMP 1987 model, very close to still being a JTM. A true collectible! The first years of JMP series saw the plexi face plate disappear and be replaced with gold brushed aluminium. JCM800 series was born when Marshall finally got rid of the rough distributor deal, probably celebrating the beginning of 1980's as well, the amps being pretty much the same with new series name. The most consistent was probably the naming in JCM900 where you could read from the code which model it was, if it was a head or a combo, how powerful it was and the number of speakers if it was a combo. The nicest thing they did with product name codes was the T and V. If it had a T in the code, it had tremolo, and if a cabinet code had a V, it had Vintage 30 speakers. Obviously A and B also signifying the cabinet being slanted or straight as well. The worst they did in naming was having a solid state JMP 2205 called Slave, a 100 W PA Slave head. Other than that they held it together.
I bought one these in Germany with a 2x12 cab for 450 Deutsche marks in 1988 (about £150 at the time) sold the cab for £50 and took the amp back home. Mine was a 1970 (inspection certificate inside had the date) ....I had a smug look on my face when I sold it for £350 in 1996.....needless to say my smugness has matured into a self loathing.....not so much for whats it's now worth but for the fact that it's a work of art that I got rid of.. A piece of Rock 'n Roll history!.......Great video Uncle Doug!
Great Video, Uncle Doug and Jack, especially in explaining and comparing the circuits Fender vs. Marshall. It is known that Marshall-amps in the begining were similar to Fender, but now it could be seen in detail. This 1987 Plexi from 1967 you analysed, meets the origin. spec reg. the Drake-Transformers exactly. The trimpot is a useful feature to bias different brands of output-tubes, which really influence the tone. Owning the same amp, it was a great pleasure for me to get this Video. Thank you very much !
What a superbly entertaining video. Thank you very much indeed, and that Plexi is in fantastic condition. It's just a shame we can't all hear it in the flesh.
Jim marshal was a drummer he got a radio ham to desing his first amp they went and got a fender amp. At that time the only tranformers were ex military. Befor the 1960 we had ac dc 120 to 240 aftrer that the whole counry was rewierd to 240 vac than laterly we went to 230 to be inline with the eu. Here we have brown live blue newtral and yellow/green earth. Earth is a local earth to the property and neutral is earth at the substation transformer.
Great video - this could be part of a tube amp design/repair curriculum. So cool to see the guts of an authentic, well-cared-for Plexi, accompanied by meaningful commentary.
Awesome!! Jim Marshall had all his solder welds colored over with a red dye to basically distinguish factory from any mods or replacement work. It appears much was replaced over the years on this beautiful amp. Even the speaker solder joints were dyed red over the joint
It's all about the integrity of the design really. Replace worn out components with similar quality parts, making sure you have installed them correctly, and there's no problem. Ultimately the thing has to sound good. Those famous Marshall players from the 60s and 70s wouuld have sanctioned any change to maintain or improve their tone. No point being precious about it.
Don’t quote me, but I think Marshall used nail polish on the solder joints. It served two purposes: 1. Protect the solder joint from oxidation. 2. So the Marshall repair department could see if any repairs or modifications were done. I don’t think anyone has found the information yet on what the exact color and manufacturer of the polish.
I'm pretty sure that Duane Allman's amp of choice was a 50Watt Marshall Bass amp... at least that's what I'd always thought, but perhaps the story is that Duane played one of these- a Fender Bassman "copy"... Anybody know about that?
I've had a really bad week. Drilled into my finger twice, cut it with a cutoff wheel (through my glove), burned on hot exhaust headers, pinched into a blood blister by a breaker bar (still numb at the tip), and my thumb knuckle cut to the bone on a nail head. Other than that.....things have been peachy :)
@@UncleDoug so sorry to hear about your woes, I've had weeks like that! Glad to see you're still chipper, though. You can't keep a good man down, even with self-inflicted hand injuries!
Uncle Doug, please don't hate me. I suggest you go talk to your doctor. I say that because I suffer from neck/head pain. Sometimes when the pain is more than I can handle what happens is my concentration becomes diminished and routine tasks become challenges and I make mistakes that I don't normally make. I'm not saying pain cause those mishaps, I am suggesting something effected your concentration and you should look into it. If it's something your doctor can isolate end remedy then all is well right away. If it's an emotional or perhaps something is worrying you, that too can cause lapses in concentration. It could even be your diet or the time of day that you ate your meals. When we are doing something we love to do we sometimes ignore eating/sleeping/resting properly because, well because that stuff is so mundane compared to our latest inspirational project. -Peter
@@PeterDad60 Thanks so much for your concern, PD, but when you routinely do a hundred risky tasks in a day, every once in a while something goes wrong. I'm all healed up now and ready for more :)
Those are Siemens EL-34s. Back then National bought tubes from all over and just relabeled and sold them. I have a lifetime supply of them new in box. The only Mullards I owned were used, so it's an a fair test, but those are the best EL-34s I ever used and they last a long time. You can still find them for not too crazy money. They are worth it. Great for hi-fi and guitar. Great video!
In Greek, the name for John is Ioannis. ( who would have thought there might be a similarity between Greek and Welch?). Typically pronounced E-O -On-Yis although my uncles would sometimes call my dad, who was first generation greek-american, Yanni or Yannis. I'm not versed enough in Greek to know if that's normal or an approved way of saying the name John, or if they were just yanking my dad's chain, especially since he was the youngest. Dad didn't teach us any Greek, he wanted us to be fully American without any accent whatsoever, so that we wouldn't grow up to know the prejudice he experienced. My mother, on the other hand, being of French and french-canadian extraction, wanted us to learn French, and made us take lessons, but we rebelled, and none of us really did become conversational in it. I can read it well enough to get around in Canada or France without any problems at least.
WOW!! What an amazing Telecaster!! My 2001 or so model Tele with Seymour Duncan pickups is hiding in the corner as we speak!! I have really enjoyed this exploration of the Marshall Plexi Amp!! so cool! I never really understood what a plexi was until now! Thanks for all you do for us!! I just noticed that this cab is just like the one that a friend of mine back in the early eighties had a Kustom cab just like this, he was really into southern rock like Allman bros band and the like, He played lead and was very very good. I was learning from him until he moved off for work. It was a sad day for me, lol. Thank you for all you do Uncle Doug!!
Really nice video .... informative & entertaining to watch, esp. for me, who knows very little about how these amps do what they do. One thing that would have been nice during the demo section would have been to jumper the two channels with a patch cable, the way that most players used this amp back in the day. This makes both volumes available simultaneously, and since the two channels are voiced a bit differently, one can come up with the classic thick JMP sounds that we all love. Thanks for a well thought out and orchestrated video.
Thanks for the great video, especially comparing the circuits. I've been learning so much watching your videos. I have a 70s 50w Master Volume 2x12 combo which I've had for 30 years and a 63 Showman (Blonde / Blackface) I picked up a few years back. Both have some minor issues - I wish there wasn't an ocean between us, I'd love to get your attention and skill on them! I watch with my cats Hattie and Jake, and then sometimes go out to the garage to tinker with my 53 F100 / early Bronco hybrid, so I enjoy every part of your videos. I'm currently using the knowledge I'm getting from watching to do a Hammond conversion amp (AO43) complete with reverb and vibrato sections from the organ, just trying to decide on Fender / Marshall / Hammond or AN Other style preamp stage. I'm way too chicken to launch into my Fender or Marshall yet!!
Uncle Doug, You do not have to claim to be a Marshall expert, or any expert claim at all. Your attention to detail and craftsmanship speaks that for you. I could only wish my videos were as half as good as yours. Thanks for sharing.
Hey Uncle Doug. Liked the vid (and actually all the vids I have seen). History tells its own story but, as you mentioned Ken Bran was the engineer - and in my opinion the absolute father of the amps that Marshall produced at the time. Jim Marshall was a driving force.I did meet Ken Bran, his office was the whole ground floor of the warehouse at Bletchley, super nice guy even to a young pup like me. I had a Park amp at the time which is a whole different story, I can send pics if you like.Jim was the marketing force and obvious face of the company. The purists like to speculate over the choices of components, actually, it was a business choice, what is available Valve amps are very forgiving (thank yoda) and will work until they can't . Enjoyed the speculation
Thanks for sharing your experiences and knowledge with us, Chris. I agree with your opinion that component choices were based on economy and availability. Fortunately, most of the old components seemed to hold up quite well.
What a great amp video, nice work Uncle Doug. There is a fellow close to me here in Florida that an absolute expert on Marshal amps and I’ve have the opportunity to sit in on a lot of repairs and learned a lot about these amps. They are really wonderful. This was a really nice video of a great amplifier, thank you! Buddy By the way, I had to add how much I love your Custom padded cabinet!!! Custom amps were everywhere when I was young and one day I’m going to find one for my own collection.
Great video!! I have never fooled around with Marshall amps, so this is a great tutorial. Jack and Ollie really nailed the "British Sound" with that amp through your Kustom cabinet. Thanks again for a great video
Thanks for the videos Uncle Doug! This is indeed a fine technological masterpiece, and you can call me funny - I just love those old ones you show us that have like a single 6SJ7 and a 6V6 and some kinda freaky art deco style cab with like cracking old snakeskin nogahide or something, those just make my day.
Thanks' Uncle Doug!Really enjoyed this video!Had to replace a H.V.Transformer in a later modal,with 6550s'! Not the easiest thing that I have ever worked on!!! : )
Brought back some great memories there Uncle Doug. My first real amp! Mine was made in 1970 (certificate inside was stamped to that date) Bought it in Germany in 1987( while serving Aunt 'Liz) for 450 marks (about £150) it came with a 2x12 cabinet. I more than doubled my investment when I got back to the U.K when I sold it in the early '90's. I keep getting told that now they go for several grand.....but it's not the money that bothers me....it's the piece of history that I let slip away.....Great video and credit to to you for showing the crisp clean tones these amps were able to produce. ( why do most people think a Marshall needs to find a place at number 11??)
Great video. This amp bleeds classic tone. I would have liked to have heard some dirty tones (that's only my personal preference though). Thank you Doug and thanks to the gentlemen who let you use this great specimen. Your videos will be learning tools for years to come.
Uncle Doug is my favorite TH-cam channel by far. I also like the guitologist and Mr. Pete(Tubalcain) Men like Uncle Doug are a rarity in these times, I hope he passes his knowledge along to others outside of youtube. we're gonna need people who can do stuff like this more and more............... Thanks Uncle Doug
I bought a small box 50, 1987 metal panel with a blown p.t. in the mid 80s for real cheap. I replaced the faulty P.T. I did a gig with it and the sound man came up at the end of the nite and said "That amp sounds great." He didn't say the band did or I did but the amp did. I'll take it.Uncle D, I love your 427 with a two barrel carb. My old bass player had a 65 442 with a LS6 454 Corvette engine that he bought new in a crate because his uncle worked at a Chevy dealer. I can smell the exhaust now. Hot rod cars, Hot rod guitars and Hot rod amps,Yea Man. You wanna hear some of the best L.P./Marshall tone? Duane Allmanns solo on Eat A Peach,Mountain Jam sol after the drum and bass solo. He gets every shade of tone from clean to infinite sustain,Don 't get me started.
amazing you bring out a custom cabinet. 50 plus yrs ago. Battle of the Bands was comman all over the U.S. played many. there was one band had all matching custom amps /P.A.drummers mother maid there uniforms/Paul Rever style. back then wanted a red custom BUT the local dealer and my father did not see/eye/to eye. all good still playing in a local band. {no custom}. THANKS.
Thanks UD ... very fun and interesting video. I have one I am contemplating sending you ... gotta think a little more about it, but pretty sure we is gonna do it (we discussed it about a year ago). Will likely be in touch about it soon. Thanks again. Nothing better or more exciting than an Uncle Doug vid to rejuvenate a worn out ole man at the end of the day.
I will shoot you an email this weekend@@UncleDoug .. and tell you what all is up. I think it will be interesting to see you go through it, analyze and service the thing.
Hi @Uncle Doug! Just a little precision about your analysis of the preamp parts of the 1987, around 24:55. I think that the purpose of the 2k7 resistor and 680n bypass cap is to exacebate the hight frequencies. Effectively, 2k7 resistor, without bypass cap, tends to reduce the gain of the stage. Normally, bypass cap is present to leave the DC operating point set by the cathode resistor, and eliminate the cathode resistor for AC signal to recover the maximum gain for the stage. Here, the little value of the bypass cap show us the willingness of Jim Marshall to bypass the cathode resistor only around a certain frequency (around 400Hz). In other terms, the gain of the stage is lesser in low frequency than in high frequency, other way to do a bright boost! I take this message to thank you for your videos, you can not know how it helped me in my studies in polytechnic! Greetings from Switzerland!
Good to see you with a Marshall UD and your schematic comparison between Fender and Marshall is intriguing - thanks! Casey seems to be giving you a verbal opinion - probably not so keen on the flavour of her latest treats UD - what a great transformation in a cat! Strange the bias was so low when all other restoration looks so well done - perhaps the player preferred the sound of underpowered tubes. I like the way you've altered the biasing but kept it under the limits to protect the tubes. Think I heard my song at the end. Get the impression you enjoyed playing through that. Nice!
Ahh, love the Marshall Plexi examination. Don't get to see inside one of those often. Also digging' the scenery & the desert welcoming spring w/wildflowers & cacti in bloom. Thanks, U.D. !
My roommate made a leslie 12 " speaker with a horn on the opposite side that spun both speakers using slot car blade brushes on a commutater that worked and sounded better than any leslie except a little shaking was noticed ! It was the best natural chorus tone ive ever encountered ! The speed motor was from a sewing machine !
Nice sounding amp for sure, and the playing isn't too bad either. Your turning into quite the rocker. I remember bands playing back in my high school days using the Leslie cabinets.
Perfect match with the Custom cab, sounds more like a Fender amp should sound. Marvelously clear dynamic 3D sound! Splendid. The genious cherry on the cake is the Voltage selector with ohms settingd for 4 8 16ohm speakers made it a workhorse. Here in the UK almost every re-hearsal/ recording studio had one of those JTM45s on standby. I think the smaller 45/50watt out performs the 100watt for Guitar, for bass you need 2x100watts minimum and 4x 4x12 cabs to keep up with a JTM45. Great viddy, thsnkyou.
That was for me; a great lesson in schematic reading by comparison, if nothing else. I was also pleased to hear it being played at a level that gave the kind of breakup a consumer in '66-'67 would consider acceptable and not wide open as would later be the norm. Nice glassy highs and throaty growl from a beautifully made and cared for 'tele. Thanks for another great clip Uncle Doug!
Some of the best content on you tube.... those of us who sub uncle doug know it all too well . We love ya uncle Doug . I've never met you but I have no doubt you are a good man and neighbor And damn what a sweet amp
Very few things make me drool, you had at least two in this video I'm not crazy about single coils but I'll take the tele too. Oh and you just told me I can build the leslye myself. Thank you kind sir.
what a beauty. could've jumpered the channel to make that cool cabinet really bark! but I fell in love with the leslie...the shop bucket is such a sick touch
HUNTS caps are well known in the UK....i still have a bunch of them, dated 1969 (i bought them just for the looks) , nice big cans , rated 100muF/500Volts....out of curiosity i put them current limited at 5mA on a HV-power supply and they even still can handle their rated voltage and came down to 2nA leak current....not even one out of eight, of which i got, is leaky after all these years....and now...hunt for these HUNTS ;)
You really do a great job on these walk throughs. I learn more with every video. This is one in particular I have been curious about and was literally going to do some comparisons when this video popped up in my list. I have been wanting to find a way to design my own amp for some time, for poor boys like myself. Of course, getting parts together comes at such an expense that you really can't justify the cost over a decent complete used amp at a decent price. Transformers are the killer, of course. But from what I am able to gain from these videos is a real starting point to finding the right Transformers and then the right parts to go behind them. Best of all, what to do with them afterwards. :) Hope you are doing the best. Keep em coming.
Thanks so much :) I understand your situation, AZ, and wish you the best with your amp-building project. You might want to watch my "Building a Fender Champ from Spare Parts" video series.
@@UncleDoug , Oh, I am going to watch them all. I watched the entire series on how amplifiers worked and a full layer of mud was removed from my eyes. Can't tell you how valuable you have been. At the end, I could literally draw boxes and lay out an amp with the understanding of what components I would need in general. And how they would work. Then I slept... so have to rewatch now. :p Huge thanks Uncle Doug.
I'm pretty sure you are a genius and your teaching style is inspiring. I have an old Califone model 24 (hums harder than "Little Bitty Pretty One") I am going to "recap" and change to a three prong plug. I will check values on resistors, valve bias, etc... pretty much based on your backlog of youtube videos. With one hand in my pocket and a chop stick, I sally forth. Thank you.
Man what’s gonna happen when guys like Doug leave us ? I’ve always been to impatient to study electronics took a vocational course back in 1979 and thought I’d loose my mind on the constant upgrades and knowledge on the subject but will say that Doug makes it very easy to understand and he truly is a master at it 👍
Comments and Corrections: 1.) At 3:12 I meant to say built with "British" parts, not Fender parts. 2.) At 11:15 The transformers are all built by Drake and are correct and original for the amp. They are labeled with part numbers, not EIA numbers. 3.) At 13:30 This is one of the original Hunt's electrolytic caps, disconnected and left in place for appearance. 4.) The schematic used in the comparison is for a later model JMP (Model 2204), but it matches the demo amp fairly well. The correct schematic is for a model 1987. 5.) At 16:13 I meant to say trim "pot" not trim "cap".
Doug, love your videos man. I'm in the way straight to my first build but I have some troubles with the power transformer design and calculations. Can I ask you a few things? I need some advice and knowledge
Chris, have you watched the videos I've posted that deal specifically with that topic? They contain virtually all I know on the subject and are readily available. If you still need help, I can try to answer your questions here or on my FB page: Uncle Doug's Vintage Amps.
Yes Doug, and the series about that topic was as great as all the others. In fact, it's because of your videos that I feel encouraged to learn and try my first 5E1. But here is my doubt. I saw that some more actual amps like the Orange OR15, based on the Tiny Terror, have a way to reduce from 15W to 7W by taking the half voltage from the secondary of the power transformer. The well known original transformer for 5E1 is 325-0-325 and I want to know if I can make some sort of 325-180-0-180-325 for the selectable voltage to the rectifier tube and how to make it, what type of things must be considered. Also I want to add others changes to the original schematic such as gain pot, presence pot, shape (Orange style tone), and a 3 selector switch to ad by pass cap on both sides of ECC83 which is the only valve I've found at my local supplier
@@christiancosta7997 It's plausable to use a transformer with different voltages, although you'd need to be aware of possible bias changes. What you're describing is basically the same as "browning" the amp with a variac... cutting down all of its voltage a bit. Take a look at a schematic from the ORIGINAL Vox Night Train, not the G2. They used a Triode mode on the EL84s to cut volume. www.prowessamplifiers.com/schematics/Vox/Night_Train_Updated.html
Just saw this. I was thinking the same on the schematic. They had a JMP 50W 1987U model that had tremolo, from what I can see online. No idea what exact model number this is. Anyone know? The cool thing about this one is you can jumper those inputs and blend the two channels in parallel. Talk about overdrive!
Great video again Doug. The amp really sounds great. The most remarkable feature of this amp is it's managed to survive for 52years without getting any white paint splatter on the top of it. Keep posting the video's, you put smiles on a lot of people's faces. Thank you.
You're welcome, Ima. Thanks so much. I guess British spiders wear diapers :)
Ollie is such a beautiful cat. That being said, I would give my left nut for a Marshall that clean. I was disappointed to see that someone had removed the original Mustard caps. FWIW the original JTM 45/Bluesbreaker amps were exact copies of the Bassman circuit and used KT-66 tubes. Those tube along with the Radiospares output transformers gave the early amps their unique tone. The tube rectifier tells me that this amp is a transition model right before they went to SS rectification. Another great vid, thanks Uncle Doug.
Thanks for your input, Robert & Tom :)
I have spent the last 4 months watching Uncle Doug videos. They are amazing and his humour is my cup of tea!! Very informative and to the point. Hope there are lots more to come!!
Thanks so much, Richard. We intend to keep producing videos for as long as we're able......so stay tuned :)
Best 40 minutes I've spent in a while .. thanks, Doug.
You're welcome, Bob.
Yesss. I never expected you to go over a plexi. Yet, here we are. Thanks so much Uncle Doug.
You're welcome, Bryan :)
You are the best, Uncle Doug! Thumbs up. And that is one sweet vintage amp.
Wow.....thanks so much, Ken :)
I own a 1970 JMP 50 watt head that I purchased new in 1970! It was my first serious amp, and I paid $595 for it with the 8x10 speaker cabinet which I sold just a few years later. It is in ‘near-museum’ condition and at first glance looks identical to this beauty. Mine, however, has an aluminum front panel and solid state rectifier, which is actually my preference sonically. I have replaced all electrolytics and set bias each time I’ve replaced power tubes, aiming for a just slightly warm 38mA. I’m not worried about using EL34s as I’ve replaced them several times. I’ve even kept the original Mullard EL34s but one is shot.
What’s really important is, it sounds glorious! I have recently decided to never sell it. The tolex is in even better shape than this beautiful plexi’s. I will use it until I die. It’s going in my will to my daughter. She doesn’t play, but maybe it will buy her a car one day.
It sounds like a wonderful amp, Peter. I don't blame you for keeping it.
Uncle Doug Thanks Doug. Sorry for coopting your comments section. I felt like I was looking at a twin, couldn’t help it. I really enjoy your videos and would like to have contact info to recommend you to customers. I only work on my own stuff but from what I’ve seen, I would send anyone to you. I don’t know how to pm someone on TH-cam. Any ideas?
I'm real selective on what I work on, Peter. It would have to be a vintage tube amp, the older the better. If a customer wants more info, they can contact me here or on my FB page, Uncle Doug's Vintage Amps.
Uncle Doug But of course, selective, I picked up on that right away. Thanks for the info. Most of my customers are very choosy, and I would just refer them to you directly. I’m sorry I’m not on FB, but you can check me at www.artisanmobile.com if you’re interested.
Another fantastic video for us ampoholics, Uncle Doug. That is one killer Marshall! Thank you for putting the time and effort into these videos. I'm sure it is not easy and very time consuming. I always look forward to your videos & appreciate them very much! Keep them coming!
You're welcome, Buddy. We will :)
The 50 watt Marshall's from this era are exquisite! Among the finest tube tones ever produced came through these amps! Beautiful specimen as well!
Thanks, Pat. I would tend to agree after this experience.
I remember the days in dublin( in the 80s) that you pick up one of these things for 150bucks a pop, in fact i was walking by a music store one day and they were tidying the shop they had a skip outside (large waste disposal bin)and there on top was a marshall 50watt head in good condition for its age, i asked they guys why they were tossing the thing out and they said it had a blown transformer , needless to say it came home on the bus with me. replaced transformer and used it for 10 years then sold it for 1000bucks just when the vintage bullshit started ...true story Doug...PS love the posts
Wow!! Somebody's trash definitely can be someone else's treasure. Great find !!!
@@UncleDoug Persactly. I bought 2 of these in the mid-80s when nobody wanted old single-channel amps with no FX. Needless to say they're not for sale now. I love playing through them.
Thanks Uncle Doug for this very comprehensive review and curcuit comparison. I've learnt more about valve circuit design from you than any of the tutors I had when I did my trade 35 years ago. Your passion is obvious and appreciated!
You're quite welcome, Vinny :)
I am thrilled to see you look at this amazing amp. Too bad you couldn't demo this thru a Marshall 4x12 cab, like God intended.
I'm glad you enjoyed it, Darren. Sadly, I was fresh out of 4 x 12" Marshall cabinets, but I really thought that the Kustom 3 x 15" performed well :)
Thooly Doo sorry I am late to the party. I appreciate the awesomeness of the 4 x 12 cab, but the cab itself has some great history, and Pete T. was involved. Seems the Marshal 50W amps were typically played through two 2x12 Bassman cabs (oh, the horror). Jim promptly designed and sold the 1960 4x12. It was his 100W amps that gave birth to the “stack”.
I nearly teared up watching this, it reminds me of my old Marshall amp, that I traded-in in the 80's, stupidly. The biggest problem with them was 1) Don't loose the power cord!!!!! and 2) the selectors at the back could drop out during transport, everyone used to tape them up. Thanks Uncle Doug great video again.
I'm glad it brought back some fond memories, GK. The power cord problem is resolved, but we'll need to get some spare jumpers for the rear.
Of course Jack and Ollie would start off with the Stray Car Strut. Thanks for a look into another great project, Doug.
You're welcome, GM :)
Nice video walk through of a classic amp Doug. I've a super clean 1966 gold script JTM45 MKII Plexi head (30w RMS) that I've owned and used since around 1976 with GEC KT66's, Mazda GZ34, ally chassis and rare cream backplate with single speaker out. Wish you could see/hear it, as you clearly really appreciate the quality design and manufacture that Ken Bran and Co put into these early point to point modded bassman beauties for Jim Marshall to market.
I would love to be able to see and hear it, Chris. It sounds like a fabulous amp.
@@UncleDoug Thanks Doug. I was 18 when I picked it up for £90 ... just seen as a 10yr old used amp back then ... how times change. Had a couple of other good amps over the years but never been tempted to part with this one.
If you ever do, let me know. I have 95 pounds burning a hole in my pocket :)
@@UncleDoug Now that's what I call real humour 😁 ... all the best Doug from your newbie subscriber 👍
That modern style mains connector is called IEC. That Leslie sounds delicious.
Thanks twice, OMM :)
All of this was beautiful. Thank you Doug! Mike
Ok I know you're not going to crank it, respecting the owner. Gorgeous vid, please say you want to build one!
I hadn't thought of it, John.....but it's an interesting suggestion.
@@UncleDoug go for it, and add that mojo your great expertise leads! It's gonna be awesome!
After your first successful Marshall build, if you want to start making a lot of money, I suggest you run a few well placed advertisements asking for trainees - people interested in building guitar amps. Hire 6 for starters. Then you train them and supervise the construction of new Marshall Clone amplifiers. Then offer them for sale. If you do this in a legal way I am sure you will absolutely end up with more money than you need. You might even be doing the world a service by introducing new guitar amplifiers under your personal brand name and hopefully at an affordable price. -Peter
P.S. Jim Marshall hired a tech right out of school (before he finished school) doubled his salary and had him have a go at making the kind of amp being asked for my the guitar payers visiting his shop. The technician is responsible for the modifications, Jim used his "ear" to say when it was right and "good enough". He sent a few of them out as pre-production units and people wanted to buy them after using them. The future was right there in the making and he went into production.Mr. Marshall did not do any design, lets be clear on that. The student tech is 100% responsible for all the electrical design modifications which were based upon Jim's blessing of the sound. So all in all Mr. Marshall actually was involved as it was he who knew what tone/sound was needed. The tech was clueless about music but he could solder, sketch out schematics and know a little bit about how to change the component values to achieve a change in tone.
I am not 100% sure of what I just wrote because I was not there! I read this here on TH-cam a couple of years ago. It makes sense as why would a drummer ever have a need to modify a guitar amplifier components? Why did he hire a electric tech to do the work, if he could do it himself? The answer is he could not he needed the skills of a specialist, an electrical technician who was familiar with components that go into making a guitar amplifier. You "Uncle Dough" have that knowledge and I hope you take us up on the idea of building your own Marshall amp and then take me up on my suggestion to train a a small workforce and open up a small amplifier shop where you live. You have so many TH-cam followers I think you already have a huge customer base. I know you are not interested in wealth. Your wealth is knowledge. But, I would love to purchase a Marshall type amp from you. Think about the future of all the young people who you provide training and employment. That might be a "Legacy" that you never considered. Maybe you could even start a tech school for building guitar amps. You could retire (again) and just watch it grow. Your knowledge of electronics will be shared and will flourish. That's another "Legacy". Uncle Doug's knowledge get's passed on and lives on!
The best tube compliment I liked was Mullard EL84 and Ruby 12ax7. Wow what a fantastic sound in all of my 3 marshalls I used in 2006.
Thanks for sharing, Monty.
Very nice, I especially enjoyed the component by component circuit comparison with detailed explanation. The cats are sounding tighter every time they play, I really enjoyed the opening song. Thanks for sharing.
You're welcome, Michael. The kitties send their regards, suggesting that you may be distant relatives :)
Good day to you Uncle bob. This one was special for me. I am 54 and was a fender guy first. Swore off marshalls cause everyone else had them. Then it happened ......I plugged into a guys garage rig of 7 rows of full stacks with two heads on each one. A bit of a collector. Anyways that was it for me. Wasnt soon after that that i got a 68 baby box non export plexi. Its gone now but i replaced it with a metropoulos super lead plexi clone. Wow. I learned that billy squire lick early on and its a real pleasure to hear you do it. Thanks for the great insights. Loved the comparison of the two circuts. Now doesnt the bright fender input drop to 34k because of the switching jacks throwing 2 68s in parallel. This is something i would love to hear explained.
Thanks so much for your nice comments, Marc. Please watch my video on the Fender Input Circuit. It explains it all in detail.
What a treat! Thank you for taking the time to do this and using the Tele. Now if you can find a vintage Hiwatt in as good condition. :))
Thanks, Andrew. A relative has one......but he lives in Chicago.
A vintage Hiwatt is a thing of true beauty when you get a look inside. It just might be worth a trip to Chicago!
What a fantastic specimen ! Thanks for the tour!
You're welcome, Rick :)
Oh my heavens, A "lay down" transformer plex with a tube rectifier. That is one rare and collectable / coveted amp. Marshall, Marshall, Marshall!
Amen, Ronald :)
Ronald Anderson mesa
Very interesting and inspiring video! Thank you so much Uncle Doug and greetings from a '67 Marshall 1986 and '68 Marshall 1987 owner from Finland!
It was our pleasure, J. Thanks for watching and commenting :)
Clapton used one in the Yardbirds, Jeff Beck prefers a 50 watt Marshsall of that design, and Peter Green used that same exact model to record The Supernatural.
Pat Nichols isn’t this also the amp of Al Di Meola’s heyday?
@@hubbsllc I don't know. Di Meola played a lot of different styles back then. Possibly.
In the 80s I was in a rock band where the lead guitarist had one of these (but ss rectifier), a '61 LP Junior and an MXR Distortion+ and the rhythm guitarist had a 100W SupaLead and an Explorer.
It was aural heaven, and complete carnage.
Sorry, didn't hear that last remark.
Me? Thunderbird into a DR103.
In England in the 80s they were giving these amps away (I bought a mint DR103 for £100 - it's still mint and worth a metric shitonne more now. Even got the bloody Bulgin plug/socket, a source of worry. If that lead goes missing at a gig...) .
Yes, but the tinnitus is worse in the left ear.
Since they were all 4 input amps you could jumper them all together. Speakers were 2x15 H&H, Hiwatt 4x12 (Fanes) 2 Marshall 4x12 and a Marshall 2x12, many of them original 25W speakers.
It was EPIC!
In fact epic did not do it justice. BIBLICAL.
Thursday? So am I, let's all have a cup of tea.
Yeah, just had to tell you.
p.s. the idiot guitarists sold all that gear (I nearly cried). I still enjoy mine.
Wow, thanks for all the very interesting info, guys :)
Thank you for another outstanding and well presented explanation of the workings of these two amplifiers. Your channel never ceases to be a wealth of knowledge and understanding for us mere mortals who never could have aspired to this level of comprehension of this historic and beautiful old world technology. I hope the joy you have shared with us over the years is returned to you 10 fold.
You're quite welcome, Anthony. We sincerely appreciate your very kind words and wish you the very best.
This video, maybe the first 5 minutes, made me spend like 6+ hours searching and discovering Marshall series and model name codes history, completely ignoring everything from lunch to whatnot. Now I can finally say I have some idea of where the series and units get their codenames and how they wrap in the evolution of different series. I can happily say that in the beginning it almost made sense, got very quickly out of hand and then around JCM900 it started making better sense once again. With little quirks that make it inconsistent.
They ended up mixing everything up with MR modern cabinet series where they could've used the existing codenaming to preserve some connection. Now everything is just 1960 or 1936. One of the things that has made the least sense was the 1922 vs 1936 cabinet. Same 2x12" cabinet, just slightly smaller dimensions in 1922.
But now it makes sense, 1959 (whatever series it was, JTM, JMP, JCM, reissues) was always 100 W 'Super Lead' head (first introduced when JTM100 came out), while 1987 was the same in 50 W, but only 'Lead' (except the first entry, JTM45 was naturally only 45 W). The main guitar heads of Marshall through the history. 2203 was the 100 W 'Master Volume Lead' and 2204 was the 50 W version of it (since JMP to JCM, essentially JCM were the same products, but in the 80's). Then there was also 2205 and 2210 which were 'Split Channel Reverbs' in 50 and 100 W (reversed this time, but you can see the code actually serving some function for once), which to my understanding were the first to include channel switching (FINALLY) and also reverb, happy days. There might have been changes throughout the different series (JTM, JMP, JCM) to those different Lead heads in sound and some might be more favourable than others (JTM45 being 5881->KT66, JTM50 series starting to phase out GZ34, JTM100 being solid state rectifier and going from KT66 to EL34. US distributor swapped from EL34 to 6550 in JMP series for busted tubes over transport and people thinking theirs 6550 amps sounded worse, but some liked the increased high frequencies).
It seems like the early JMP 18 W combos had EZ81 rectifier in 1965 (the prototypes of JMP series) and were replaced by 20 W models in 1967, which had solid state rectifiers. However, 1967 also being the year of transition from JTM to JMP and this amp being 1967 JMP, it's very possible that they were still using the last stock of GZ34 rectifiers in JTM 1987 models and this is a very, very early JMP 1987 model, very close to still being a JTM. A true collectible!
The first years of JMP series saw the plexi face plate disappear and be replaced with gold brushed aluminium. JCM800 series was born when Marshall finally got rid of the rough distributor deal, probably celebrating the beginning of 1980's as well, the amps being pretty much the same with new series name. The most consistent was probably the naming in JCM900 where you could read from the code which model it was, if it was a head or a combo, how powerful it was and the number of speakers if it was a combo. The nicest thing they did with product name codes was the T and V. If it had a T in the code, it had tremolo, and if a cabinet code had a V, it had Vintage 30 speakers. Obviously A and B also signifying the cabinet being slanted or straight as well. The worst they did in naming was having a solid state JMP 2205 called Slave, a 100 W PA Slave head. Other than that they held it together.
Wow.....thanks for all the info, Yuppi.
Great info. Thanks...
I bought one these in Germany with a 2x12 cab for 450 Deutsche marks in 1988 (about £150 at the time) sold the cab for £50 and took the amp back home. Mine was a 1970 (inspection certificate inside had the date) ....I had a smug look on my face when I sold it for £350 in 1996.....needless to say my smugness has matured into a self loathing.....not so much for whats it's now worth but for the fact that it's a work of art that I got rid of.. A piece of Rock 'n Roll history!.......Great video Uncle Doug!
Great Video, Uncle Doug and Jack, especially in explaining and comparing the circuits Fender vs. Marshall. It is known that Marshall-amps in the begining were similar to Fender, but now it could be seen in detail. This 1987 Plexi from 1967 you analysed, meets the origin. spec reg. the Drake-Transformers exactly. The trimpot is a useful feature to bias different brands of output-tubes, which really influence the tone. Owning the same amp, it was a great pleasure for me to get this Video. Thank you very much !
You're quite welcome, Klaus. Thanks so much for your very nice comments.
What a superbly entertaining video. Thank you very much indeed, and that Plexi is in fantastic condition. It's just a shame we can't all hear it in the flesh.
I agree, David. We'll all have to get together some day and have a massive jam session.......and beer & barbecue bash.
Jim marshal was a drummer he got a radio ham to desing his first amp they went and got a fender amp. At that time the only tranformers were ex military. Befor the 1960 we had ac dc 120 to 240 aftrer that the whole counry was rewierd to 240 vac than laterly we went to 230 to be inline with the eu. Here we have brown live blue newtral and yellow/green earth. Earth is a local earth to the property and neutral is earth at the substation transformer.
Thanks for the detailed info, Aj :)
Pretty ironic that the two greatest manufacturers of guitar amps weren't guitarists.
Great video - this could be part of a tube amp design/repair curriculum. So cool to see the guts of an authentic, well-cared-for Plexi, accompanied by meaningful commentary.
Thanks, Jed. We're glad you enjoyed it.
Awesome!!
Jim Marshall had all his solder welds colored over with a red dye to basically distinguish factory from any mods or replacement work. It appears much was replaced over the years on this beautiful amp. Even the speaker solder joints were dyed red over the joint
I wondered what that red stuff was for.
Thant's an interesting bit of info, KV. Maybe I need to hunt down some red dye :)
Any working, gigged, 52-year-old amplifier is like Grandpa's hammer. Burned resistors, bulging caps etc., belong in a bin, not in an amplifier.
It's all about the integrity of the design really. Replace worn out components with similar quality parts, making sure you have installed them correctly, and there's no problem. Ultimately the thing has to sound good. Those famous Marshall players from the 60s and 70s wouuld have sanctioned any change to maintain or improve their tone. No point being precious about it.
Don’t quote me, but I think Marshall used nail polish on the solder joints. It served two purposes:
1. Protect the solder joint from oxidation.
2. So the Marshall repair department could see if any repairs or modifications were done.
I don’t think anyone has found the information yet on what the exact color and manufacturer of the polish.
I'm bracing at the potential for April Fool's shenanigans, but something tells me this is the real deal!
I thought that the date of posting might arouse some suspicion......but in this case, the video is legit.
I was waiting for the Uncle Doug chainsaw :))
If your show was in Netflix I would have kept my subscription. Uncle Doug Show needs a TV deal!!. Thanks again UD!
We're available......as long as the pay includes lots of catnip and beer :)
Chris squire Bass player For YES played his Rickenbacker RM1999 (4001S) through a 100 watt Marshall for many years
Thanks for the input, Patrick.
I'm pretty sure that Duane Allman's amp of choice was a 50Watt Marshall Bass amp... at least that's what I'd always thought, but perhaps the story is that Duane played one of these- a Fender Bassman "copy"... Anybody know about that?
@@bradincaliphas There's some early pictures with a JTM 45 Plexi and the tall 4x12" cab but later on .. no idea
Thanks!@@zankyalbo2208
Nice amplifier 🎉
Yes, indeed.
Anytime you open a vintage Marshall you realize you are on hallowed ground.
Amen, Sting :)
You are a *wonderful* presenter! Thank you for your very enjoyable videos!
You're welcome, 4B. Thanks !!
Really is quite the orator
I see scraped knuckles, which leads me to think some work on the 'rod has been taking place. How's it going?
I've had a really bad week. Drilled into my finger twice, cut it with a cutoff wheel (through my glove), burned on hot exhaust headers, pinched into a blood blister by a breaker bar (still numb at the tip), and my thumb knuckle cut to the bone on a nail head. Other than that.....things have been peachy :)
@@UncleDoug so sorry to hear about your woes, I've had weeks like that! Glad to see you're still chipper, though. You can't keep a good man down, even with self-inflicted hand injuries!
Uncle Doug, please don't hate me. I suggest you go talk to your doctor. I say that because I suffer from neck/head pain. Sometimes when the pain is more than I can handle what happens is my concentration becomes diminished and routine tasks become challenges and I make mistakes that I don't normally make.
I'm not saying pain cause those mishaps, I am suggesting something effected your concentration and you should look into it. If it's something your doctor can isolate end remedy then all is well right away. If it's an emotional or perhaps something is worrying you, that too can cause lapses in concentration. It could even be your diet or the time of day that you ate your meals.
When we are doing something we love to do we sometimes ignore eating/sleeping/resting properly because, well because that stuff is so mundane compared to our latest inspirational project.
-Peter
@@PeterDad60 Thanks so much for your concern, PD, but when you routinely do a hundred risky tasks in a day, every once in a while something goes wrong. I'm all healed up now and ready for more :)
Those are Siemens EL-34s. Back then National bought tubes from all over and just relabeled and sold them. I have a lifetime supply of them new in box. The only Mullards I owned were used, so it's an a fair test, but those are the best EL-34s I ever used and they last a long time. You can still find them for not too crazy money. They are worth it. Great for hi-fi and guitar. Great video!
Thanks for the nice comments and info, Sean.
That's a really noisy bypass cat.
The amp is cool too.
Cheers,
- Eddy
Thanks, Eddy. Yes, she really craves attention at the worst times :)
This is like opening up the treasure chest! If you weren't great with amps, you have a voice for Radio! Enjoying this one.
Thanks, James :)
That assembly name might be Ioan (capital i), a Welsh variant of John.
Da iawn!
Thanks, B55. That would make sense.
In Greek, the name for John is Ioannis. ( who would have thought there might be a similarity between Greek and Welch?). Typically pronounced E-O -On-Yis although my uncles would sometimes call my dad, who was first generation greek-american, Yanni or Yannis. I'm not versed enough in Greek to know if that's normal or an approved way of saying the name John, or if they were just yanking my dad's chain, especially since he was the youngest. Dad didn't teach us any Greek, he wanted us to be fully American without any accent whatsoever, so that we wouldn't grow up to know the prejudice he experienced. My mother, on the other hand, being of French and french-canadian extraction, wanted us to learn French, and made us take lessons, but we rebelled, and none of us really did become conversational in it. I can read it well enough to get around in Canada or France without any problems at least.
Gobs and Gobs of praise for bringing to us this magnificent item of the 1960's (EW).
You're welcome, EW.
That old Marshall through the leslie was the most amazing tone just like Peter Framton in the 70s. Rock on Doug you rock.
Thanks, J. I too thought it was really unusual.....and nice :)
WOW!! What an amazing Telecaster!! My 2001 or so model Tele with Seymour Duncan pickups is hiding in the corner as we speak!! I have really enjoyed this exploration of the Marshall Plexi Amp!! so cool! I never really understood what a plexi was until now! Thanks for all you do for us!! I just noticed that this cab is just like the one that a friend of mine back in the early eighties had a Kustom cab just like this, he was really into southern rock like Allman bros band and the like, He played lead and was very very good. I was learning from him until he moved off for work. It was a sad day for me, lol. Thank you for all you do Uncle Doug!!
You're welcome, Jack. Thanks for watching and for all your very nice comments.
Really nice video .... informative & entertaining to watch, esp. for me, who knows very little about how these amps do what they do. One thing that would have been nice during the demo section would have been to jumper the two channels with a patch cable, the way that most players used this amp back in the day. This makes both volumes available simultaneously, and since the two channels are voiced a bit differently, one can come up with the classic thick JMP sounds that we all love.
Thanks for a well thought out and orchestrated video.
You're welcome, Andrew. Thanks for the suggestion.
Beautiful review, the Marshall and the Leslie are amazing rock machines, thanks!!!
Thanks so much, A56.
Super good vid, Uncle Doug. What a great channel to learn and enjoy your vast knowledge of electronics!! Keep em coming!!
Thanks, BU. We will :)
I had that same amp back in the day. Wish I had appreciated it more at the time.
I am blown away from your videos Uncle Doug, I must get back to my work and its hard...
Thanks, Amir. Once you have retired, as I have, you can spend all day working on projects of your own choosing. It's wonderful :)
Thanks for the great video, especially comparing the circuits. I've been learning so much watching your videos. I have a 70s 50w Master Volume 2x12 combo which I've had for 30 years and a 63 Showman (Blonde / Blackface) I picked up a few years back. Both have some minor issues - I wish there wasn't an ocean between us, I'd love to get your attention and skill on them! I watch with my cats Hattie and Jake, and then sometimes go out to the garage to tinker with my 53 F100 / early Bronco hybrid, so I enjoy every part of your videos. I'm currently using the knowledge I'm getting from watching to do a Hammond conversion amp (AO43) complete with reverb and vibrato sections from the organ, just trying to decide on Fender / Marshall / Hammond or AN Other style preamp stage. I'm way too chicken to launch into my Fender or Marshall yet!!
You're welcome, MH. Best of luck with your continuing education and projects.
Wow! That rig is beautiful! Sounds amazing! Great stuff!
Glad you liked it, K.
Uncle Doug, You do not have to claim to be a Marshall expert, or any expert claim at all. Your attention to detail and craftsmanship speaks that for you. I could only wish my videos were as half as good as yours. Thanks for sharing.
You are most kind, RS. I am far from an expert on Marshall amps, but I'm trying to help others learn about them just as I am doing.
What a treat! Thanks for bringing us along.
Thanks for coming along, GG :)
Hey Uncle Doug. Liked the vid (and actually all the vids I have seen). History tells its own story but, as you mentioned Ken Bran was the engineer - and in my opinion the absolute father of the amps that Marshall produced at the time. Jim Marshall was a driving force.I did meet Ken Bran, his office was the whole ground floor of the warehouse at Bletchley, super nice guy even to a young pup like me. I had a Park amp at the time which is a whole different story, I can send pics if you like.Jim was the marketing force and obvious face of the company.
The purists like to speculate over the choices of components, actually, it was a business choice, what is available
Valve amps are very forgiving (thank yoda) and will work until they can't .
Enjoyed the speculation
Thanks for sharing your experiences and knowledge with us, Chris. I agree with your opinion that component choices were based on economy and availability. Fortunately, most of the old components seemed to hold up quite well.
What a great amp video, nice work Uncle Doug. There is a fellow close to me here in Florida that an absolute expert on Marshal amps and I’ve have the opportunity to sit in on a lot of repairs and learned a lot about these amps. They are really wonderful. This was a really nice video of a great amplifier, thank you! Buddy
By the way, I had to add how much I love your Custom padded cabinet!!! Custom amps were everywhere when I was young and one day I’m going to find one for my own collection.
You're welcome, Buddy. Thanks for your very nice comments.
Great video!! I have never fooled around with Marshall amps, so this is a great tutorial. Jack and Ollie really nailed the "British Sound" with that amp through your Kustom cabinet. Thanks again for a great video
You're welcome, Jim :)
Thanks for the videos Uncle Doug! This is indeed a fine technological masterpiece, and you can call me funny - I just love those old ones you show us that have like a single 6SJ7 and a 6V6 and some kinda freaky art deco style cab with like cracking old snakeskin nogahide or something, those just make my day.
You're welcome, Ideal. By coincidence, I had planned to present an ancient little amp (exactly like the one you described) in my next video :)
Thank you, great video and nice to see such an old Marshall inside and out.
You're welcome, Erik.
You are the first person i have ever seen (in 47 years) that writes the number 4 the same way i do.
We must be brothers, Mike......separated at birth. Although I was already 24 at the time :)
Thanks' Uncle Doug!Really enjoyed this video!Had to replace
a H.V.Transformer in a later modal,with 6550s'!
Not the easiest thing that I have ever worked on!!! : )
Brought back some great memories there Uncle Doug. My first real amp! Mine was made in 1970 (certificate inside was stamped to that date) Bought it in Germany in 1987( while serving Aunt 'Liz) for 450 marks (about £150) it came with a 2x12 cabinet. I more than doubled my investment when I got back to the U.K when I sold it in the early '90's. I keep getting told that now they go for several grand.....but it's not the money that bothers me....it's the piece of history that I let slip away.....Great video and credit to to you for showing the crisp clean tones these amps were able to produce. ( why do most people think a Marshall needs to find a place at number 11??)
Thanks for your nice comments and share memories, FF.
Wow, the tone with the leslie unit was really amazing, very "deep" sound!!!
Thanks, Sebastian. I posted a video showing how to build your own.
Great video. This amp bleeds classic tone. I would have liked to have heard some dirty tones (that's only my personal preference though). Thank you Doug and thanks to the gentlemen who let you use this great specimen. Your videos will be learning tools for years to come.
You're quite welcome, Chuck. Thanks for your very nice comments.
Uncle Doug is my favorite TH-cam channel by far. I also like the guitologist and Mr. Pete(Tubalcain) Men like Uncle Doug are a rarity in these times, I hope he passes his knowledge along to others outside of youtube. we're gonna need people who can do stuff like this more and more............... Thanks Uncle Doug
Wow....you're quite welcome, Nick. Thanks so much for all your very nice comments.
I bought a small box 50, 1987 metal panel with a blown p.t. in the mid 80s for real cheap. I replaced the faulty P.T. I did a gig with it and the sound man came up at the end of the nite and said "That amp sounds great." He didn't say the band did or I did but the amp did. I'll take it.Uncle D, I love your 427 with a two barrel carb. My old bass player had a 65 442 with a LS6 454 Corvette engine that he bought new in a crate because his uncle worked at a Chevy dealer. I can smell the exhaust now. Hot rod cars, Hot rod guitars and Hot rod amps,Yea Man. You wanna hear some of the best L.P./Marshall tone? Duane Allmanns solo on Eat A Peach,Mountain Jam sol after the drum and bass solo. He gets every shade of tone from clean to infinite sustain,Don 't get me started.
Thanks for all the nice comments and reminiscences, Halbert.
amazing you bring out a custom cabinet. 50 plus yrs ago. Battle of the Bands was comman all over the U.S. played many. there was one band had all matching custom amps /P.A.drummers mother maid there uniforms/Paul Rever style. back then wanted a red custom BUT the local dealer and my father did not see/eye/to eye. all good still playing in a local band. {no custom}. THANKS.
It was the stoutest speaker cab I could find in my amp room, DH......glad it brought back good memories.
Thanks UD ... very fun and interesting video. I have one I am contemplating sending you ... gotta think a little more about it, but pretty sure we is gonna do it (we discussed it about a year ago). Will likely be in touch about it soon.
Thanks again. Nothing better or more exciting than an Uncle Doug vid to rejuvenate a worn out ole man at the end of the day.
You're welcome, Scott. I hope you decide to send it. We're running out of subjects for videos :)
I will shoot you an email this weekend@@UncleDoug .. and tell you what all is up. I think it will be interesting to see you go through it, analyze and service the thing.
Hi @Uncle Doug! Just a little precision about your analysis of the preamp parts of the 1987, around 24:55. I think that the purpose of the 2k7 resistor and 680n bypass cap is to exacebate the hight frequencies. Effectively, 2k7 resistor, without bypass cap, tends to reduce the gain of the stage. Normally, bypass cap is present to leave the DC operating point set by the cathode resistor, and eliminate the cathode resistor for AC signal to recover the maximum gain for the stage. Here, the little value of the bypass cap show us the willingness of Jim Marshall to bypass the cathode resistor only around a certain frequency (around 400Hz). In other terms, the gain of the stage is lesser in low frequency than in high frequency, other way to do a bright boost! I take this message to thank you for your videos, you can not know how it helped me in my studies in polytechnic! Greetings from Switzerland!
Thanks for your very detailed input, Eric. We really appreciate your time and interest.
Good to see you with a Marshall UD and your schematic comparison between Fender and Marshall is intriguing - thanks! Casey seems to be giving you a verbal opinion - probably not so keen on the flavour of her latest treats UD - what a great transformation in a cat! Strange the bias was so low when all other restoration looks so well done - perhaps the player preferred the sound of underpowered tubes. I like the way you've altered the biasing but kept it under the limits to protect the tubes.
Think I heard my song at the end. Get the impression you enjoyed playing through that. Nice!
Thanks so much, Guy. We really appreciate your thoughtful comments.
So pleased to see you again with such a passionate and refreshing contribution.
Thanks, D.
@@UncleDoug Call your website 'Doug's your uncle', and all will be well.
Hats off to Uncle Doug! Thanks a ton sir! Great work as always
Thanks, Luis.
Uncle Doug has been practicing! I love you my friend.
It's mutual, Mr. B......but it really was Jack & Ollie :)
maestro Uncle Doug sharing his wisdom and rocking wicked game with the leslie!! Excellent video!!
Thanks, L14. Guilty as charged :)
Ahh, love the Marshall Plexi examination. Don't get to see inside one of those often. Also digging' the scenery & the desert welcoming spring w/wildflowers & cacti in bloom. Thanks, U.D. !
You're welcome, Jerry :)
My roommate made a leslie 12 " speaker with a horn on the opposite side that spun both speakers using slot car blade brushes on a commutater that worked and sounded better than any leslie except a little shaking was noticed !
It was the best natural chorus tone ive ever encountered !
The speed motor was from a sewing machine !
It sounds like an interesting creation, IS.
Nice sounding amp for sure, and the playing isn't too bad either. Your turning into quite the rocker. I remember bands playing back in my high school days using the Leslie cabinets.
Thanks, John.......glad you enjoyed it.
Perfect match with the Custom cab, sounds more like a Fender amp should sound. Marvelously clear dynamic 3D sound! Splendid. The genious cherry on the cake is the Voltage selector with ohms settingd for 4 8 16ohm speakers made it a workhorse. Here in the UK almost every re-hearsal/ recording studio had one of those JTM45s on standby. I think the smaller 45/50watt out performs the 100watt for Guitar, for bass you need 2x100watts minimum and 4x 4x12 cabs to keep up with a JTM45. Great viddy, thsnkyou.
Thanks so much or your interesting input, Giulio :)
Yeah, I know Mark, I'm into them now. God Bless Uncle Doug! He's the best!
Wow, thanks so much, TG.
That was for me; a great lesson in schematic reading by comparison, if nothing else. I was also pleased to hear it being played at a level that gave the kind of breakup a consumer in '66-'67 would consider acceptable and not wide open as would later be the norm. Nice glassy highs and throaty growl from a beautifully made and cared for 'tele. Thanks for another great clip Uncle Doug!
Some of the best content on you tube.... those of us who sub uncle doug know it all too well . We love ya uncle Doug . I've never met you but I have no doubt you are a good man and neighbor
And damn what a sweet amp
Thanks so much , IA :)
Thank you Uncle Doug ! It's time for me to come back in a new ''learning phase'' and follow you as before ! Happy to see that you're doing great !
You're welcome, Eric. Thanks !!!
Very few things make me drool, you had at least two in this video I'm not crazy about single coils but I'll take the tele too. Oh and you just told me I can build the leslye myself. Thank you kind sir.
Thanks, David. I posted a video several years ago showing how I built the Leslie unit in the video.
@@UncleDoug I will definently look for it.
what a beauty. could've jumpered the channel to make that cool cabinet really bark! but I fell in love with the leslie...the shop bucket is such a sick touch
Thanks, J......glad you liked it :)
HUNTS caps are well known in the UK....i still have a bunch of them, dated 1969 (i bought them just for the looks) , nice big cans , rated 100muF/500Volts....out of curiosity i put them current limited at 5mA on a HV-power supply and they even still can handle their rated voltage and came down to 2nA leak current....not even one out of eight, of which i got, is leaky after all these years....and now...hunt for these HUNTS ;)
I'll be hunting for them, TC :)
As a happy Marshall owner, (A Superbass MkII - modded to Superlead specs), I really enjoyed your tour of the amp. THANKS!
You're welcome, Ray :)
the Leslie sounds absolutely magical !
You should hear it in person, when the sound is fully 3-dimensional.
Thanks for sharing this Doug. It's amazing to see the differences between the two big amp companies. Great history lesson in amps!
You're welcome, PC :)
Great video Doug. Many thanks.
You're welcome, SS. Thanks !!
Thanks Doug! Very nice lesson!
You're welcome, Robert.
You really do a great job on these walk throughs. I learn more with every video. This is one in particular I have been curious about and was literally going to do some comparisons when this video popped up in my list. I have been wanting to find a way to design my own amp for some time, for poor boys like myself. Of course, getting parts together comes at such an expense that you really can't justify the cost over a decent complete used amp at a decent price. Transformers are the killer, of course. But from what I am able to gain from these videos is a real starting point to finding the right Transformers and then the right parts to go behind them. Best of all, what to do with them afterwards. :) Hope you are doing the best. Keep em coming.
Thanks so much :) I understand your situation, AZ, and wish you the best with your amp-building project. You might want to watch my "Building a Fender Champ from Spare Parts" video series.
@@UncleDoug , Oh, I am going to watch them all. I watched the entire series on how amplifiers worked and a full layer of mud was removed from my eyes. Can't tell you how valuable you have been. At the end, I could literally draw boxes and lay out an amp with the understanding of what components I would need in general. And how they would work. Then I slept... so have to rewatch now. :p
Huge thanks Uncle Doug.
Amazing amp Doug! What a treat! Thank you and your trusting friend! KC is looking happy as a clam.
You're welcome, Han. My friend is quite impressed by all the comments on his amp.....and KC is the happiest little clam you could ever hope to see :)
I'm pretty sure you are a genius and your teaching style is inspiring. I have an old Califone model 24 (hums harder than "Little Bitty Pretty One") I am going to "recap" and change to a three prong plug. I will check values on resistors, valve bias, etc... pretty much based on your backlog of youtube videos. With one hand in my pocket and a chop stick, I sally forth. Thank you.
You're welcome, Mike. Best of luck with it :)
Man what’s gonna happen when guys like Doug leave us ? I’ve always been to impatient to study electronics took a vocational course back in 1979 and thought I’d loose my mind on the constant upgrades and knowledge on the subject but will say that Doug makes it very easy to understand and he truly is a master at it 👍
Wow, thanks so much, Doug. We plan on being around for a while yet, so don't start worrying prematurely :)
~Uncle Doug~,electronics,cars and rock and roll,my kinda guy,thanks for sharing man!
The big three :) You're welcome, Ted.
so excited for this sam! watching it at work! couldn’t wait for home to see it.
We hope you really enjoy it, MH.