I did the same thing with my grandpa but we made mine into a mini Fender 65 reverb style amp I have a RCA 12AU7 tube for the preamp I prefer cleans and the other tube is a 6V6 and the spring reverb tank I bought on eBay My style is more like Luther Perkins when I play I play classic country and Rockabilly and blues I don't use pedals and the speaker is a 8inch Jensen C8R I get that late 60s Luther Perkins tone I also use flatwound strings I took out the gain knob so it's just volume mids treble bass single reverb knob and I took out the FX select and the the white button is now a bright switch and I added a classic tube amp on off switch we took out the PCB board it's now hand-wired point to point like back then And I also turned a Fender frontman into a mini 1952 style Bassman style tube amp it's also got 12AU7 tube in the preamp I have a 6L6 tube 6inch custom bass guitar speaker to fit in the amp
@@martinstubeampworkbench2299 yessir I'm 21 years old my grandpa is 68 that man is the most hard-working guy there is even when he's not working on electronics and woodworking me and him work outside fixing other things like chicken coops for example typical country boy stuff howdy from North Carolina
G'day there The circuit schematic you were referencing to was incorrect for this year of "silver face" Fender Vibro Champ. Fender's initial B+ was 355V on the AA764 circuit in the early 60s (for the "black face" VCs) but raised it to 420V on the late 60s and 70s models using the AB764 circuit. There were also changes to the filtering caps going from 20/20/20uF to 40/20/20uF, which is the capcan you used.
Your job was ok, but your analysis of the power amp is wrong, sorry to say that. I am the owner of the model 2165 rp. It contains the pcb named "GP2". My amp was made in January 1980. The pcb of your amp looks different; it may be the "GP3" version. There ist not much difference electronically. I call these amps the "NEW", the "MODERN" MusicMan powerAmps. These amps are not anymore "hot", the powertubes are surprisingly "cold". These amps don't copy anymore the "Williamson" design, the basis of all the Fender and Marshall Power-Amps since the end of the 1940s. They use a new invention - a power transistor working as a "floating cathode resistor". The old Williamson design was used in the "early" MM Amps. These amps had a "normal" phase-splitting-design, featuring both triodes of a 12AX7 (ECC83). The splitted signals were fed into the CONTROL GRID of the EL34 (6CA7) or 6L6; this control grid had to be very negative (depending what type of tube was used) to control the "bias" (the current through the tube in idle state). The current through a 6CA7 or 6L6 in a typical "Williamson-Amps" is something between 30 to 40 mA. The new design is revolutionary different: The control grid is not used anymore. A positive voltage of +22 Volts is there (look at the 220 Ohm resistor, it is there for safety reasons). The signal is splitted by the two op_amps in IC8. The Motorola Power transistors JE 1692 act as "floating cathode resistors". The current through the Emitter-Collector path is "dancing" depending on the signal-voltage at the BASIS of these transistors. This was a VERY NEW design - possible because of the availability of these new transistors. The "bias" (the current through the power-tubes in idle state) is only between 6 to 7 mA (25 mA / 3,9). The "new design" is also found in amps with 6L6 power tubes - for example in my second MM Amp, the 2475-75 amp with two 12 inch speakers.
Very interesting explanation! Thank you. And I have to admit: I didn’t knew that, this new amp design is new for me as well. Surprising, that other manufacturers never picked up this revolutionary technology. They rather stuck to the traditional way of phase splitting. But anyhow, I appreciate your comment.
I'm about to do some work on one of these that I purchased in November. Reverb doesn't work, needs recap, and I want to replace a bunch of the carbon comps. This is my first time working on an amp, but I've been researching amp electronics, practicing soldering, and studying the schematic for half a year at this point. So glad you posted this video. I've rewatched the one on Brad's guitar garage at least 10 times at this point.
Good gracious! The first amp, you gonna work on is a Mesa! That’s plucky. I’m happy, that my video is helpful, though I can not cuss as good as Brad. But he’s a real expert, he knows what he’s doing. Good luck for your repair project. Be carefully, amps contain lethal voltages. Greetings from Germany
Clapton played a Musicman HD-130 reverb modded for a bit more gain than stock. The early version had a 12ax7 phase inverter tube and no reverb, like a fender bassman. I have both, the earlier one sounds better to my ear. They came with sylvania 6CA7 output tubes.
I bought a really clean used. 112. 65 watt recently at a pawn shop for $150. Late 70s or early 80s. Speaker had been replaced with a cerwin vega. Loud and proud. A fender made better !!! Clean great for most styles. Clean lead amp
Hi Martin, I wish Kitty Hawk would have mounted the pots to the panel like Boogie did, they did get that right. It looks like the faceplates could have been made on the same machine as my M1s faceplate!, they are almost identical.
Hey Andy Mesa Boogie is bad, Kitty Hawk is worse. Not a pleasure to do repair jobs at all. But when they finally work, it’s a good feeling! Maybe both companies had the same suppliers, though Kitty’s where made in Germany and Mesas in California. They both used Mallory filtercaps for instance. But though they are thousands of miles ( kilometers) apart, the design seems to be the same crap😆 Who knows?? Have fun!
Have a late 64 early 65 vibro champ in collecting condition and a 1971 silver face I've modded the hell out of. LOVE THESE AMPS !!!!!! Lucky I got mine when they were cheap !! Hahha
Heres another miracle - I have a mint 1965 Vibro Champ which is all original except for the same 1K 1W resistor. I only use the amp at home so I have not replaced the electrolytics as it is working just fine. Is this a mistake?? I like the fact that it is all original and I will leave it to my Son when I go. Mine is the AA764 circuit so the can cap is 20,20,20uf which is not easy to find in an original style. ( in the UK ) What would you recommend?? Great video by the way!
Thank you very much! Well, my customer plays gigs regularly with this little gem, so it needs to be reliable. That’s why I changed the cap can. If you want to replace the electrolytic capacitors some day, there is a company named CE manufacturing. They offer can caps as a drop in replacement that look the same as the old one. You can order them from Tube Amp Doctor or Banzai Music, Berlin. Both suppliers ship international. Have fun with your miracle in black tolex! Greetings from Germany
1950's national amp would not have ceramic Jensen, it would have P10Q Alnico. What model are you building with a 12AX7, most National amps that look like this, I know have 6SL7 or 6SJ7 preamp tubes. Of course, a few late ones have 12AX7. I see now you say 6616 but where is the second 12AX7 for the Tremolo? That said you did a very nice work on the cabinet but this would only fool a young man.
Thanks a lot! Yes, Valcos can be a rat nest, or look like an exploded spaghetti factory. But they sound and look cool. I like them , especially the tremolo versions. I build a similar amp with tremolo years ago. Other than the example in the video, I never sold it, it’s still my favorite. Welcome to the channel!
I have a KH M1 100 watt head the reverb is weak. is there a layout schematic available for the M1? or an owner's/service manual? I have looked all over the net for info, it is very limited. I have found 2 wiring schematics, one of which seems to match my amp. I think the other is a redrawn copy of one by some else, that is similar, but different too. there are no pics or videos on the web of the guts or repair of an M1. everything else seems to work, except the weak reverb. they were supposedly not known known for strong reverb, but it used to have a lot more effect than it does now. Have you ever worked on an M1? is the output section board supposed to be cockeyed like that?
Schematics of Kitty’s are a good kept secret. The rare ones in the www are handdrawn and hard to read. I never had an M 1 on the bench, but I put a link down below to a video I did last year about a KH Custom, a pretty desaster, too. If your tremolo is weak, my bet is on the driver tube. These poor little suckers have to stand a very high voltage in these reverb circuits, that shortens their life . If you want to have an overall stronger reverb, try a 12ax7 in case you find a 12au7 there. Higher gain-stronger effect. Greetings from Germany ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rODHzxWEh60.htmlsi=ts2lZ_gW-DBZWhJ9
@@martinstubeampworkbench2299 Thanks for your reply. It sat for 15 years or so so I pulled the chassis before I fired it up slowly with a variac. all was good, with about 100-130 watts input current and 120 volts. then I found the red sig wire had fell off the return jack of the effects loop that the guy I bought it off of said did not work, so that fixed that I believe, I have yet to test it. I have some tubes to swap around to try for that. Does the M1 have tremolo? there are no controls for it, but you know, it did seem to have a very slight almost vibrato like thing going on, but its very slight. Possibly in that chip on the effects loop board? very Interesting.... other than that it seems worth spending the for the 12 electrolytics (gasp) and other caps (bypass, etc), and 3 or 4 noisey pots. they all need to be changed. it looks like marshall style metal shaft will work fine, I just have to double check the bushing length. it's a kick ass amp and worth saving I believe.
As I mentioned, never had one of these on the bench. But if there is no control knob for tremolo speed and intensity, the amp has none. Interesting problem, a tremolo effect in an amp without tremolo. Probably hard to trace the source of this weird problem. Another hairpuller! Good luck!
I owned the 2x12 version of this amp. The salesman at the music store talked me out of buying the Fender Twin Reverb that I’d always wanted. I regretted that decision every single day until I finally sold it to buy a Marshall JTM30 30 watt 2x10 combo amp which absolutely blew the door off this amp.
@@darwinsaye for starters it did not have that Fender "sparkle". To me it sounded like "just another amp". And when I jammed with friends it had no power to cut through. What I hadn't realized when I auditioned it at a comfortable room volume in the music store was that as you turned up the volume there wasn't much more available. It got buried onstage. A Fender Twin was the beast that could dominate any stage and still can.
Great video. I wish you would have spent alittle more time exploring and explaining the circuit. The reason is documenting the past. Who designed these old Supro's and I'd liked to have seen a better overall view of the original circuit. I may want to build one of these someday, yes I can get a schematic but is the schematic true, and there are not alot of these around in there original state. I encourage you to make longer videos also. But I really enjoyed it. Thanks for the video.
Thanks a lot! I actually build a few Valco clones in the last couple of years. And I still had two of them, when this Supro came in for repair. I compared the sound and all three where amazingly close. Though my builds where less noisy. I didn’t do a lot of exploring or explaining, because these circuits have a really simple design. If you want to build one of these, look for these schematics: Supro 6606, Gretsch 6151 or Supro 6616 T which is my favorite because of the outstanding tremolo circuit. The question, who designed these circuits is not easy to answer. There was never one single person like Leo Fender, who left his unique footprint in the music scene. Valco amps where an industrial, a mass product. Valco amps never got popular like Marshall and Fender products and neither got the attention they deserve. So, when the company went out of business, not a lot of informations where preserved. Here are two videos that document one of my builds, in this case without tremolo: National, Supro, Valco: How to build a Valco Guitar amp clone ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Cf-72SJoHZk.html Valco National Amp Clone Sound Demo ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-S_9ZW8IGIkE.html
I would have…..but I am living in Germany, so I assume, that won’t help you. But it’s a 10 watt 80 ohm cement resistor . A 100 ohm resistor will do the trick as well. I don’t know, where you are located at, in case the US try mouser as a supplier for electronic stuff, or browse eBay. But if you decide to stick your fingers in there, beware of the high voltage. Make shure the HT capacitors are discharged.
I had 2 Music Man amps back in the day (mid 80's). A 65 Reverb head and an HD 130 head . Both were crazy reliable and sounded great thru my 4x12 marshall cabs. I wish I still had them.Today I have a Mesa Boogie V combo and a Fender Blues Jr.
I had one of those in the early eighties. I loved it. Worked great with the few pedals we had then. Very loud. Durable, never let me down, not once. Very well made. Wanted a Marshall, got a Marshall. Loved that Amp though. 30 years later I got another one. It's here now next to my Marshall
I have owned two MM amps...both the 212 HD model....and I believe both were either 120 watt or 130 watt....mine had a huge amount of headroom and were impossible to push into distortion because they were so FKN LOUD....I eventually bought a Soldano 2 channel foot switchable pre-amp and had an extra input that sent the Soldano straight to the MM's output section.....both MM amps had broken reverb when I bought them...the first had the entire reverb unit and enclosure bag removed from the bottom of the combo enclosure.....the second had the entire reverb still intact , but I discovered that the reverb pan had a small half moon cut into it for some of the circuitry wiring to pass through.....the reverb pan itself was being hung on springs , my guess is to lessen stage vibrations from transferring to the springs carrying the guitar signal , but when the amps were in a bumpy van with bad shocks on the way to a gig , or being mishandled by idiots , the reverb pan would shake like a hammock on a boat in a storm , and the sharp half -moon edge on the side would slice the circuitry wire because they were being thrifty and used short wires that had tension on them....a longer wire without the tension would just get pushed aside by the swinging reverb tank....I then understood why the first one I bought had the entire reverb unit removed ....I bought an Alessis microverb that I patched in after the Soldano instead of rescuing the original reverb.....both amps had Celestion Vintage 30's in them .....this rig sounded absolutely amazing !
@@martinstubeampworkbench2299 Definitely mate.. l dunno what model, but he was using MusicMan by 79/80. Mates 50w.. whack a Tele through it & there's that sound. Like the channel mate, lve subbed.. so lve got a bit of catching up to do
@@martinstubeampworkbench2299 Apologies mate, thought ld replied! Yeah definitely, Strummer was using MusicMan... Edit: repeated myself! Like the channel mate, have a great Xmas!
@@martinstubeampworkbench2299 Yeah Martin, Sth Australia... hour or so out of Adelaide. Unfortunately the prices we pay for guitars and gear here is ridiculous. I've subbed mate, so no doubt we'll chat again...oh, you were getting some nice tones out of the MM!
Thanks for this! A MM RD210 2 x 6CA7 and square Eminence 10" were my first "real" amp and served me well through many recordings and occasional live performances. I often recorded in my flat and had to play quiet but the built-in distortion circuit did a great job to mimic a "swetting" amp, at least in my recordings.
Interesting, and effective testing. I've got a Music Man 112 RD. Nice sound, but I always thought it had a bit too much self noise. After hearing how quiet you got the Amp on your bench, I think there's probably something wrong with mine.
What kind of noise is it? In case of hum, new filtercapacitors might do the trick. They are 40 years old. It’s like worn out tyres or brakes on your car. You wouldn’t hesitate to change them, either. If it is white noise (hiss) new op amps could help. You need LM 1458 op amps. Swapping them is easy, because they are mounted in sockets. And they are dirtcheap. Worth a try.
@@martinstubeampworkbench2299 The noise has a little bit of hiss, more low hum, sort of the sound when blowing out air with your mouth in the shape of an "O" or what one might think that powerful electricity would make when surging through a circuit. The Amp is 100 Watts. I was shocked when you swapped out the op amps in the video, and how much difference that made. Thanks for advice.
I just stumbled across your channel. Nice to see a fellow tech giving MM amps some love. I think they’re wonderful. I got one just because of Johnny Winter. He said in an interview once that he always kept the Bass and Middle controls on zero, and the treble turned to 10 on his MM amps. That’s insane.
Like I mentioned: they can’t be bad. People like Johnny Winter, E.C, and all the others had a good reason to choose them. And as a fellow tech: let’s preserve these jewels for generations yet to come. Greetings from Germany
