As an ex-navy ET (electronics tech) you bring back memories of instructors I had explaining tube behavior and circuitry. Now in my early seventies, I just finished rehabbing my 1960’s Magnatone M-15 during Covid days. Your vids gave me a lot of suggestions and ideas for trouble shooting various issues. Great stuff. Thanks.
My father served in the Navy 6 years repairing radios amplifiers and television equipment in the Seabees 1969 too 1976 was in Spain Newport RI I wish I had his knowledge he is 74 now with dementia and still is fixing radios he horded so many tubes and iron and test equipment before he left and we use it almost everyday Nothing like USN Iron
Sadly this video will have to wait until later as I have a complete refret and anxious customer waiting. But it will be the highlight of my evening while sipping a cool drink. Already gave it a LIKE as Uncle Doug never disappoints his viewers.
😂LOL! I know exactly what you mean! I feel for ya, I am ditching my responsibilities to as I often do, to watch this one! I suppose we are fortunate that our dear Unkie isn't too prolific with the output and timing of videos as of lately.... I would never get anything accomplished other than cutting in line here at the peanut gallery to make inconsequential and long replies and musings. But yeah+1 on like before viewed.
I got to a feral mother as she was defending her last kitten from a neighbors pitty . I put both female cats in my house while I went thru some wall-to-wall counseling with a knuckle dragger . Both mom and kitten warmed up to indoor life and soon became very loving with long life . I don't mind the little rabbit hole we dive down when it's with our fur family . Great info all round , Thank you .
Thanks for your care of our furry pals, RJ. It's inconceivable to me that anyone would allow harm to come to a kitten or puppy.....or any other small animal.
So nice that you have such a kind heart toward kitty cats. You've taken in ferals that otherwise would not have faired well at all and brought them to health, have paid for vet visits and invited to be a part of your loving family along with Jack & Casey. Great to see kindness and caring.
Victoria is indeed a builder of impeccable quality. Today's episode was well executed, and had proper deducing of the purported issues. The modifications have proven to be a signature of Uncle Doug's sensible preventative steps to longevity. I look forward to the next installment. Stay safe and secure dear uncle, there's a clown shoe living next door.
Thanks Doug and thanks to Chelli for the gift. He lives down the road from me but have yet to meet him. Someday. Have a great summer Doug and stay cool. 😎
Thank you, Uncle Doug, for another classic "Uncle Doug" video displaying solid methodology and logic leading to a happy result. Thank you also for the humour and the personal touch, behind the scenes, especially with Mitzi. She had a wonderful stroke of luck, finding you. Cheers!
Hi Uncle Doug ! You have a natural gift for keeping the presentations fun and interesting. Also, my 3 year old dog Copper goes BANANAS every time we see Jack, Casey, or the new kitty.
I know you always like to hide Easter eggs in your videos. I noticed that your closing frame was filmed before you added the negative feedback Loop modification and the 8 ohm tap. Can't fool me Uncle Doug, I'm always paying attention. You are absolutely the most entertaining and knowledgeable amplifier repair technician on TH-cam. Looking forward to the next video.
Thanks so much, DM, we really appreciate your kind words. Yes, the video scenes are often shot out of order and can keep you on your toes, watching for anachronisms.
I paused this at bout 15 minute mark, in order to see what DMMs are being used. Found them on ebay, and bought one. I'll get a second one if its really cool. I figured UD would choose a decent tester. When I looked through the reviews, sure enough, I see that UD has posted favorably lol. Thanks for making my life easier, sir.
I built that 5F4 tweed Fender Super clone from Mojotone kit. I'm a fan of class 'A' phase-inverters. I made a few mods: used a 5AR4, added an additional 47uF cap to the power supply, added a bias control potentiometer, rewired the choke coil to feed only the 12AX7 tubes; which increased the power output, installed a 50 watt output transformer. Great fairly lightweight 35-40 watt amp. :)
Wow. I have had one of these cap tester. and also sold it after getting an esr meter. What a mistake. These load the caps and are a great way to test. Loved the video.
Hello Doug, Thank you sir! I really have learned something very different, yet very relevant from each of your excellent videos. And a warm appreciative shout-out to all the great classic amplifier enthusiasts / owners that send you their weary, ailing gems....so, for that I thank you and them. In your own style, you consistently prove, we Seniors, Rock. All the best!
Hey Uncle Doug, I built my first amp last year from a marshall 20W kit. I just followed the instructions and it worked at the first try. Before starting the build i had no experience in electronics, and id been reading about safety and circuits for a couple months. So i wanted to understand how the circuit actually works. And then i found your channel on youtube. I know you hear this all the time but i wanted to thank you for the best instructional videos out there. The way you explain things makes it so easy to understand. Your channel is a national treasure! Im now getting ready to build a fender champ all from scrapped parts from old radios and reel to reel recorders, very much like your video. So again thank you for being the best teacher out there!! Greeting from an italian in Norway
Hi UD, nice video. One note to mention, I have the Fender Super Amp, and I changed the rectifier to a 5u4 from a gz34. A customer brought in the exact same amp as mine with a gz34 rectifier in it. An A/B comparison revealed quite a difference in gain. I didn't check the bias comparison, but if your customer changes the rectifier tube to a gz34, I am sure a re-bias is advised to cool down the 5881 tubes. Great video as always Uncle Doug 👍.
Another great video from Uncle Doug. One thing that should be noted regarding the kill switch on the feedback circuit. IF there's a Fender presence control, opening the feedback loop takes the presence control out of circuit as that control is part of the feedback loop. FYI.
😂my wife just went crazy @ 42:00 test tone😅, I’m sitting about 5’ across the bedroom and enjoying this jewel you’re working on with a cup of coffee, awesome video.
You always do a very nice job on your videos, and it helps a lot of people wanting to learn about amp repairs. On the speaker jacks however, the output transformer should always have a load on them when nothing is plugged into the jacks. This is why Fender always shorted the speaker jack when nothing was plugged into it. The reason being is if someone should plug a guitar into the amp without a load and then play the guitar the impedance of the output transformer will go sky-high. This can create large voltages and can cause the 6L6 tubes to internally short or cause the tube socket to arc over due to the excess hi-voltage across it. There should always be some kind of load on a tube amp to control the output transformers kick-back voltage.
This was great Uncle Doug. Love watching your step by step walkthroughs of troubleshooting. I see that you have a neighbor that trims his trees like one of mine does... They must be related.. Excited for the next video!
11k views, but only 1k likes?!? What's not to like when Uncle Doug pops yet another one out of the park? I love how you're so methodical... one step at a time.
Hi Uncle Doug. I hope all is well. The craftsmanship of the Victoria is amazing. The word "symmetry" come to mind when looking at he layout. I'm still a rookie with an opinion that's worth exactly what it cost and but agree that the 7581's were incorrect, and I suspect the fizzy and unstable output you could not reproduce was caused by the tubes being starved with a cold bias. As strong as they are it would seem logical that without adequate power they would never be able to stand up and sing as intended. The Ford grille shot and Mitzi bathing herself after dinner were an added bonus to an already excellent video. Thank you so much.
Expertly and gently explained, as always. A small point for the commenters discussing 7581 and 7581A tubes: they are as the numbering suggests, similar. They are not identical however as they have different plate dissipations. Cheers, Alan Tomlinson
Man! I am so glad I found your channel! I wacth everyday and have learned so much about tube technology in the last few weeks. Just built my first 5F1 kit. I would never have thought I could this a few months ago. The videos with Rusty are always a special treat. He must be missed around the shop. And the hot rods are a whole other subject! Dude you are everything I want to be when I grow up! 😂 it's like you really are my uncle! Thanks and keep the videos coming!
Hi again Uncle. Just had to pause this video to say thank you for such a detailed and informative diagnosis. This amp really benefited from the time you have spent on it, as we all have. I sincerely hope you will be able to continue with these much appreciated & educational videos for as long as you enjoy creating them. I have learned everything I know about tube amps from you. As before, kind regards from way up here on the west coast of Canada/Vancouver! ss
this might be the longest I've EVER sat through a video (made it to the very end)! but when the information is shared with such care, it's hard to turn away (plus I love cats). I'm a mixing engineer turned VERY rookie jazz guitar enthusiast and this level of information while difficult to understand, was still very interesting. thank you for taking the time and sharing your expertise, Uncle Doug!
Thanks so much, GA. As a former teacher, I know how hard it is to maintain interest throughout a lengthy presentation. I am both flattered and glad that you did so.
Thanks UD, again, for an informative and entertaining lesson. I am enjoying your choice of test tunes (as opposed to, say, the test tones.) Cheers, hoping you and your extended species family stay well.
Worth noting…..the 5E4A used 6V6GTs. Those 7581s are closer to a 6550 than a 6L6G. All in all another fantastic repair/mod! So glad to view your tube amp prowess UD, and another cat saved! You are the best! Love from NW Colorado. Thanxz
Great review Doug. I like the Fender tweed amps, I have both a Mojotone Super tweed amp kit and a Fender '57 Bandmaster reissue hand-wired tweed amp. I love their looks and their tone.
This amp may look inconspicuous but it's a real deal beauty on the inside. That's how you build amps! And that's the way amps should be modified too. None of that kludgy bullshit I've seen in many of them, some of which made me consider an amp not ready to power up before taking care of the rat's nest inside. 17:40 it's transliterated to 5C3S and it's a directly heated 5V rectifier pretty much like 5U4GB, same heater current and voltage, but coke bottle and can withstand 550VAC instead of puny 450V. Lovely car and meowsome cat for sure :) To state the obvious, talking about spots at the base of the tail, these are very scratchy and cats just love being pet there.
You really got my hopes up there Uncle Doug - I was on the edge of my seat when it looked like you were going to restore a 23 1/4" Regular ice Scraper & Snow Brush.
I known its a year later, but that rectifuer tube is excellent. Ive been running one with a mono Allied Knight mono amp. And itnlooks great in that particular amp. I got some winged C versions for a good price. NOS pairs on the auction place.
Another masterpiece theater installment, thank you Doug! That amp sounds absolutely wonderful. I have been trying to purchase those Eurotubes bias meters ever since you demoed them a few moons back and they are still sold out! Very much hoping they return to market some day, being a much safer alternative to the shunting method that gives this particular amateur the heebies.
Thanks so much, DD. I really don't recommend the shunt method for PC measurement.....dangerous to mankind and equipment. Simply measure the voltage drop across each half winding of the OPT primary.
Wow there is something airy in the background of the sound....really nice for the ears. As if you are outdoors. Awesome video as always Uncle D! And I learn so much from this....
The presence on the 5F4 is pretty enimic. Also it should be noted that when turning off the NFB loop, it will render the presence control inop.. but not sure it would matter that much as it is pretty useless. I placed a .47u Cap in place of the .1u on my presence control and it made a difference, at least you can tell it is actually doing something now. Great work as always Uncle Doug and we learned of yet another 6L6 variant.
Hey Doug! I always enjoy the videos! I also have a Victoria 35310 (bandmaster clone). I picked mine up from an estate sale for $160 in need of a service. Now it sounds awesome! It’s from 1996.
Halfway through I'm thinking there must be something wrong with da guy's guitar or cables. I don't understand much of what you present but I love following your logical reasoning as you do your detective work.
Hello again, Doug, with another excellent video, amp, and...what a gift!. I am searching for one of these cap testers for ages!. It seems to be difficult from here in Spain. And also: be very careful with the tester, because it outputs as much as 600 dc volts in the banana jacks. Never forget to discharge it, and put the test voltage knob at its minimum, because we need to see your videos during too many years! 8-) Thanks a lot, and God bless you, Doug & the cat gang.
Almost all modern electronic equipment power supplies use a Line-to-Ground and Line-to-neutral cap as EMI/RFI filters. They are supposed to be a special XY rated safety caps that are designed to only fail open.
That Heathkit is a jewel! It's younger than my piece of Heathkit test equipment - I was given a Heathkit AQ-1 audio signal generator (circa 1957) by an old neighbor - and after a set of electrolytics, it's as solid as a rock (if you don't mind the analog frequency dial!) The head technician had a Heath cap checker similar to yours at one of the shops I worked for, and if he suspected a tech of shotgunning caps, he'd take it from the margarine tub and test it while the tech was away, then leave it on his bench with the results scribbled on a piece of paper. Needless to say, we mortals dare not step into his sanctum to test our own caps but he would break it out sometimes if we were stumped and he suspected leakage that we had missed. I wonder if someone has written a book about the whole Heathkit phenomonon - a real example of post war GI industriousness and excitement about the hi-fi craze. One thing I remember about Heathkits - when the owner was stumped by a problem, he'd bring his unit in with all of the encyclopedic manual, notes and records, and go over all of his prior troubleshooting in detail! I can't wait to see your future comparison video with the current magic box digital cap checkers. I use them, but don't completely trust them (how can a $15 ebay cap checker do the same job as the $450 B&K? circa 1975). Thanks for the great video, as usual!
Fran Blanche over at the Franlabs channel has quite a few video’s on Heathkit kits. Apparently she got started in electronics by visiting their repair facility as a child.
Very thoughtful and professional approach to the conclusion, I was thinking the whole time "why would victoria amps use orange drop signal caps in any fender clone amp they would build?" Victoria amps are normally built with the blue sprague signal caps that the victoria amp company commissioned sprauge to build to match the original fender offerings of the vintage leo fender designs.
This amp was probably built back before Victoria commissioned the blue caps you mentioned. I have a early 90's guitar mag that showcased a couple tweed clones, a Holland, and a Victoria, both used the orange drops as coupling caps back then. In fact, I remember when OD were considered the best coupling cap... I have used several kinds in various builds, and I don't have a preference at this point. I have found that tubes and speakers make the most difference to my ears. That said, I believe I can hear a subtle difference between cap types, but I'm not sure if it's real or not. People argue about this to death. I'll leave it at that.
Full credit to you Uncle Doug for the epiphany I had not too long ago drawing a parallel between bypass caps/switch pop caps and condensers in ignition distributor caps.
Great video UD! Well worth the wait. In my version of a perfect world, I would watch Uncle Doug working on a vintage gem every week, amps n hotrods! And Elon Musk would open a vacuum tube factory in Texas... Thanks for doing all you do UD. Best wishes. FW.
I wish we had the time and energy to fulfill your dream, FW :) Elon has been hanging out in the workshop lately, pondering the Twitter buy. I'll ask him about some local tube amp factories.
Wow My first Stratocaster Ibanez 1976 Silver Series...Great guitar..And My first Ap was a Super Reverb 45 Watt 1972!...I'm going out to buy a lottery ticket!
This is a great video on the troubleshooting process for the power section, and is the one I ended up following to debug my DC30 clone build after trying some less effective processes.
A sterling effort uncle doug brilliant ! and a welcome gem of entertainment as usual, `when something`s not right its wrong` as bob dylan once sang, your chanel is always right as rain !
UD, outstanding as usual. The tube swaps are funny, you have to restrict the amps to the tubes so you don't damage the power amp, so now the tubes are barely working, it's like someone I knew, tunnel ram, twin 1050 dominators, on a stock 327 in a Camaro, just "couldn't get it to start right in the morning, and had to rev it too high at stop lights", but it looked great. Also when I heard you say Hammond my ears perked up like a Dobie hearing 15 kHz, but my hopes were dashed when I realized you were talking about a transformer. Anyway hope everything continues to go well for you, and still hoping someone sends you a 144 or 147 amp to repair. The Blue Mule 🤘 Leslies Rule 🤘
I built a clone of this circuit myself a few years ago. I used Mercury inductors throughout, and I found it hit the bias numbers in the schematic just about exactly. I think I ended up with 410-420 V on the anodes at about -20 V on the grids, and that it was in its happy place there at ~ 60-70% for a pair of 5881s.
As an ex-navy ET (electronics tech) you bring back memories of instructors I had explaining tube behavior and circuitry. Now in my early seventies, I just finished rehabbing my 1960’s Magnatone M-15 during Covid days. Your vids gave me a lot of suggestions and ideas for trouble shooting various issues. Great stuff. Thanks.
Former AT here.
FTM here. Still workin on basically radar "Error" amplifiers for guitar.
That's great to hear, Rocky. Keep up the good work :)
My father served in the Navy 6 years repairing radios amplifiers and television equipment in the Seabees 1969 too 1976 was in Spain Newport RI I wish I had his knowledge he is 74 now with dementia and still is fixing radios he horded so many tubes and iron and test equipment before he left and we use it almost everyday
Nothing like USN Iron
Thanks for taking care of the kitties
As a youngster, I could never have any pets......so now I'm making up for lost time :)
🎸🙏🏻✍🏻 We all need a “Mentor”
like “Uncle Doug”!
Thank you for your devotion,
and your experiential knowledge!
Our Uncle Doug, THE TUBE GURU!!!
🎸🙏🏻✍🏻
Thanks, 1D. We are honored :)
Sadly this video will have to wait until later as I have a complete refret and anxious customer waiting. But it will be the highlight of my evening while sipping a cool drink. Already gave it a LIKE as Uncle Doug never disappoints his viewers.
Thanks so much, Martin. Spoiler alert: Keep your cool drink handy for the next video (early July).
😂LOL! I know exactly what you mean! I feel for ya, I am ditching my responsibilities to as I often do, to watch this one! I suppose we are fortunate that our dear Unkie isn't too prolific with the output and timing of videos as of lately.... I would never get anything accomplished other than cutting in line here at the peanut gallery to make inconsequential and long replies and musings.
But yeah+1 on like before viewed.
@@southboundsuarez9832 Thanks, SS. With the videos taking 2 to 3 weeks to complete, one a month is about all we can muster :)
I got to a feral mother as she was defending her last kitten from a neighbors pitty . I put both female cats in my house while I went thru some wall-to-wall counseling with a knuckle dragger . Both mom and kitten warmed up to indoor life and soon became very loving with long life . I don't mind the little rabbit hole we dive down when it's with our fur family . Great info all round , Thank you .
Thanks for your care of our furry pals, RJ. It's inconceivable to me that anyone would allow harm to come to a kitten or puppy.....or any other small animal.
Holy jeez. That's one of the nicest looking insides of an amp I've ever seen. WOW!
They really did a nice job on it.
You know when an Uncle Doug vid drops in the morning, it's gonna be a good day.
We hope so Mr. J.
@@UncleDoug Well, I was right. It turned out to be a pretty good day. Told you so! :-)
@@mr.joshua657 That's great to hear, Mr. J. I hope we were part of it.
So nice that you have such a kind heart toward kitty cats. You've taken in ferals that otherwise would not have faired well at all and brought them to health, have paid for vet visits and invited to be a part of your loving family along with Jack & Casey. Great to see kindness and caring.
Thanks so much, Daniel. We are rewarded ten-fold for our kindness.
My favorite uncle comes over for a visit! Always a good day!
Greetings, Rich. Thanks for the hospitality :)
Victoria is indeed a builder of impeccable quality. Today's episode was well executed, and had proper deducing of the purported issues. The modifications have proven to be a signature of Uncle Doug's sensible preventative steps to longevity. I look forward to the next installment. Stay safe and secure dear uncle, there's a clown shoe living next door.
I agree, Alex. Thanks so much :)
@@UncleDoug Looks to me like he intended to outright remove the tree, but had only enough saw bar length to get through the stuff above the main trunk
@@jenniferwhitewolf3784 Who knows what stupidity exists in the minds of men?" ;)
Thanks Doug and thanks to Chelli for the gift. He lives down the road from me but have yet to meet him. Someday. Have a great summer Doug and stay cool. 😎
You're quite welcome, Craig. Likewise....will do :)
Thank you, Uncle Doug, for another classic "Uncle Doug" video displaying solid methodology and logic leading to a happy result. Thank you also for the humour and the personal touch, behind the scenes, especially with Mitzi. She had a wonderful stroke of luck, finding you. Cheers!
Thanks so much, Kort. I feel lucky as well :)
Hi Uncle Doug ! You have a natural gift for keeping the presentations fun and interesting. Also, my 3 year old dog Copper goes BANANAS every time we see Jack, Casey, or the new kitty.
Thanks so much, Raymond. Regards to Copper from all of us :)
I know you always like to hide Easter eggs in your videos. I noticed that your closing frame was filmed before you added the negative feedback Loop modification and the 8 ohm tap. Can't fool me Uncle Doug, I'm always paying attention. You are absolutely the most entertaining and knowledgeable amplifier repair technician on TH-cam. Looking forward to the next video.
Thanks so much, DM, we really appreciate your kind words. Yes, the video scenes are often shot out of order and can keep you on your toes, watching for anachronisms.
I paused this at bout 15 minute mark, in order to see what DMMs are being used. Found them on ebay, and bought one. I'll get a second one if its really cool. I figured UD would choose a decent tester. When I looked through the reviews, sure enough, I see that UD has posted favorably lol. Thanks for making my life easier, sir.
You're welcome, Jay. I hope your new DMM serves you well.
So much to learn. Hard not to be overwhelmed, but I figure if I learn one thing per day, that's pretty huge. Thanks for your clarity.
You're welcome, Mark.
I built that 5F4 tweed Fender Super clone from Mojotone kit. I'm a fan of class 'A' phase-inverters. I made a few mods: used a 5AR4, added an additional 47uF cap to the power supply, added a bias control potentiometer, rewired the choke coil to feed only the 12AX7 tubes; which increased the power output, installed a 50 watt output transformer. Great fairly lightweight 35-40 watt amp. :)
Thanks for sharing this with us, Tony.
Dougs home for Stray Cats, Hot Rods and Fenders! Well done.
That pretty well covers it, Peter......but don't forget the Russian Pole Dancers.....always welcome :)
Wow. I have had one of these cap tester. and also sold it after getting an esr meter. What a mistake. These load the caps and are a great way to test. Loved the video.
Thanks !! You can still test for leakage by lifting the "downstream" end of the cap from the circuit, Monty.
@@UncleDoug Very true. Thanks Doug. Good test in almost circuit
@@montygore1200 You're welcome, Monty.
Hello Doug,
Thank you sir! I really have learned something very different, yet very relevant from each of your excellent videos. And a warm appreciative shout-out to all the great classic amplifier enthusiasts / owners that send you their weary, ailing gems....so, for that I thank you and them.
In your own style, you consistently prove, we Seniors, Rock.
All the best!
Thanks so much, RW. We do, indeed :)
Uncle Doug - good to see you again (well, see your hands anyway). Great video - keep 'em coming.
Thanks, Paul. Will do :)
That tree was having a bad day Uncle D! LOL. Thanks for always bringing laughter and levity to this old crazy world.
A bad haircut can really ruin your day, Bryan :) Our pleasure :)
That amp sounds great with P90's Top shelf troubleshooting Uncle Doug.
Hey Uncle Doug, I built my first amp last year from a marshall 20W kit. I just followed the instructions and it worked at the first try. Before starting the build i had no experience in electronics, and id been reading about safety and circuits for a couple months. So i wanted to understand how the circuit actually works. And then i found your channel on youtube. I know you hear this all the time but i wanted to thank you for the best instructional videos out there. The way you explain things makes it so easy to understand. Your channel is a national treasure! Im now getting ready to build a fender champ all from scrapped parts from old radios and reel to reel recorders, very much like your video. So again thank you for being the best teacher out there!!
Greeting from an italian in Norway
Thanks so much for the very nice comments, Marco. It's great to hear that the videos are instructive. Continued success with all your projects.
Hi UD, nice video. One note to mention, I have the Fender Super Amp, and I changed the rectifier to a 5u4 from a gz34. A customer brought in the exact same amp as mine with a gz34 rectifier in it. An A/B comparison revealed quite a difference in gain. I didn't check the bias comparison, but if your customer changes the rectifier tube to a gz34, I am sure a re-bias is advised to cool down the 5881 tubes. Great video as always Uncle Doug 👍.
Thanks for the info, Ken.
I enjoyed hearing your rhythm guitar playing. That amp sounds good too. ...and I learned a litte something today. Thank you.
That's great to hear, Greg. You're welcome.
Another great video from Uncle Doug. One thing that should be noted regarding the kill switch on the feedback circuit. IF there's a Fender presence control, opening the feedback loop takes the presence control out of circuit as that control is part of the feedback loop. FYI.
Yes, indeed, but it's worth it.
Good to see you again Unc! You must be busy or enjoying life!!!! Either way thank you for the video!!!!👍👍✌️😎🎸🎶
Thanks, Richard. Always.....you too, I hope :)
Im a new sub and Fan of your teaching . Then you go and be a kind man as well saving animals . Big Respect from So Calif .
Welcome aboard, IN. Thanks so much :)
Love you Uncle Doug! Glad yer still Kicking the 'Ol provervbial Ass, you reformed hellraiser you!!!!!
Thanks so much, WTD. We're still kickin'.....with both feet at once ;)
😂my wife just went crazy @ 42:00 test tone😅, I’m sitting about 5’ across the bedroom and enjoying this jewel you’re working on with a cup of coffee, awesome video.
Sorry if the tone upset her, Sonny, but I'm glad you enjoyed our efforts ;)
You always do a very nice job on your videos, and it helps a lot of people wanting to learn about amp repairs. On the speaker jacks however, the output transformer should always have a load on them when nothing is plugged into the jacks. This is why Fender always shorted the speaker jack when nothing was plugged into it. The reason being is if someone should plug a guitar into the amp without a load and then play the guitar the impedance of the output transformer will go sky-high. This can create large voltages and can cause the 6L6 tubes to internally short or cause the tube socket to arc over due to the excess hi-voltage across it. There should always be some kind of load on a tube amp to control the output transformers kick-back voltage.
Thanks for your helpful input, Neutro.
Bless Missy. Takee good care of her
Will do, Monty. She's a sweetheart :)
This was great Uncle Doug. Love watching your step by step walkthroughs of troubleshooting. I see that you have a neighbor that trims his trees like one of mine does... They must be related..
Excited for the next video!
Thanks so much, Anthony. The next video will be special.
Everyone needs a Workshop Cat Uncle Doug 😃👍🏻
No kidding, Meik :)
So good to hear you again Uncle Doug !:)
Thanks so much, AB :)
we know that jack is the real tech hear you never show his paws working on these amps great vid u.d.
I had special prosthetic human hands made to fit over his paws, Frank :)
11k views, but only 1k likes?!? What's not to like when Uncle Doug pops yet another one out of the park? I love how you're so methodical... one step at a time.
Thanks so much, FS :)
Another enjoyable video. LDWMJ was a nice touch for the testing...
Thanks, John :)
Thanks for the video and the laugh. That is a nifty hat rack in your neighbor's yard.
Thanks for joining us, Scott. The neighbor also gives haircuts......if you're interested.
What a pleasure this was to watch. Bless you Doug, you're a treasure.
Thanks so much, Simon :)
Hi Uncle Doug. I hope all is well.
The craftsmanship of the Victoria is amazing. The word "symmetry" come to mind when looking at he layout.
I'm still a rookie with an opinion that's worth exactly what it cost and but agree that the 7581's were incorrect, and I suspect the fizzy and unstable output you could not reproduce was caused by the tubes being starved with a cold bias. As strong as they are it would seem logical that without adequate power they would never be able to stand up and sing as intended.
The Ford grille shot and Mitzi bathing herself after dinner were an added bonus to an already excellent video. Thank you so much.
Thanks so much Randy. It's always great to hear from you. Thanks for your input.....Mitzi sends her regards :)
Hey Uncle Doug you’re sounding good!!
Thanks, Alvaro. We're happy just to be still breathing :)
Expertly and gently explained, as always. A small point for the commenters discussing 7581 and 7581A tubes: they are as the numbering suggests, similar. They are not identical however as they have different plate dissipations.
Cheers,
Alan Tomlinson
Thanks so much, Diego. We appreciate the added info.
Man! I am so glad I found your channel! I wacth everyday and have learned so much about tube technology in the last few weeks. Just built my first 5F1 kit. I would never have thought I could this a few months ago. The videos with Rusty are always a special treat. He must be missed around the shop. And the hot rods are a whole other subject! Dude you are everything I want to be when I grow up! 😂 it's like you really are my uncle! Thanks and keep the videos coming!
We're glad you found us too, Joe. It's great to hear that the videos are helpful. Will do :)
🎸🙏🏻✍🏻 We all need a “Mentor”
like “Uncle Doug”!
Thank you for your devotion,
and your experiential knowledge!
🎸🙏🏻✍🏻
Our Uncle Doug, THE TUBE GURU!!!
Great video uncle Doug I love the mod for the 4 ohm and 8 ohm speaker jack and nfb switch.
Thanks, Nigel. Glad to hear it.
Hi again Uncle. Just had to pause this video to say thank you for such a detailed and informative diagnosis. This amp really benefited from the time you have spent on it, as we all have. I sincerely hope you will be able to continue with these much appreciated & educational videos for as long as you enjoy creating them. I have learned everything I know about tube amps from you. As before, kind regards from way up here on the west coast of Canada/Vancouver! ss
Thanks so much for your very nice comments SS. We really appreciate them.....and you. :)
I like the shopcat. Also like the oldschool capacitor tester
Thanks, GJ. Mitzi is becoming more helpful with each new day :)
this might be the longest I've EVER sat through a video (made it to the very end)! but when the information is shared with such care, it's hard to turn away (plus I love cats). I'm a mixing engineer turned VERY rookie jazz guitar enthusiast and this level of information while difficult to understand, was still very interesting. thank you for taking the time and sharing your expertise, Uncle Doug!
Thanks so much, GA. As a former teacher, I know how hard it is to maintain interest throughout a lengthy presentation. I am both flattered and glad that you did so.
I really love your videos!.. you've given me the insight and confidence to work on my own amps...thanks so much Uncle Doug!!
That's great to hear, Mike. Keep up the good work :)
Thanks UD, again, for an informative and entertaining lesson. I am enjoying your choice of test tunes (as opposed to, say, the test tones.) Cheers, hoping you and your extended species family stay well.
Thanks, Mark. Glad the video was appreciated.
Worth noting…..the 5E4A used 6V6GTs. Those 7581s are closer to a 6550 than a 6L6G. All in all another fantastic repair/mod! So glad to view your tube amp prowess UD, and another cat saved! You are the best! Love from NW Colorado. Thanxz
Thanks so much, ATL :)
2 diff tweed supers. The second version Used 588/6L6
Gee Whiz Uncle Doug,,,I think this is the most enjoyable video yet,,,love the felines too,,,,miss the catscans,,,God Bless you and yours !!!
Thanks so much, Tom. We aim to please :)
Another satisfying morning viewing. Thanks.
Glad to hear it, Ray :)
This sounds great Dug, amazing amplifier. Thanks you brother.
Agreed, Harmon. Our pleasure :)
Great review Doug. I like the Fender tweed amps, I have both a Mojotone Super tweed amp kit and a Fender '57 Bandmaster reissue hand-wired tweed amp. I love their looks and their tone.
So do I, Tony. They are wonderful amps.
Nice to see you again Uncle Doug!!!!
Thanks, VM. It's nice to be seen :)
Awww… we have a stray that adopted us that we call Missy Kitty too.
She's a real sweetheart, Mr. B......just like Miss Kitty :)
Mary Jane's Last Dance-sounding great!
Thanks, BB :)
Another enjoyable video - I was worried you were going to actually give up but in the end you found something to change for the better.
Thanks, John. Apparently the problem is solved.....the owner is quite pleased.
This amp may look inconspicuous but it's a real deal beauty on the inside. That's how you build amps! And that's the way amps should be modified too. None of that kludgy bullshit I've seen in many of them, some of which made me consider an amp not ready to power up before taking care of the rat's nest inside.
17:40 it's transliterated to 5C3S and it's a directly heated 5V rectifier pretty much like 5U4GB, same heater current and voltage, but coke bottle and can withstand 550VAC instead of puny 450V.
Lovely car and meowsome cat for sure :)
To state the obvious, talking about spots at the base of the tail, these are very scratchy and cats just love being pet there.
Thanks for all the great comments, Keri. I agree across the board.
You really got my hopes up there Uncle Doug - I was on the edge of my seat when it looked like you were going to restore a 23 1/4" Regular ice Scraper & Snow Brush.
Sorry for the letdown, AG :)
I known its a year later, but that rectifuer tube is excellent. Ive been running one with a mono Allied Knight mono amp. And itnlooks great in that particular amp. I got some winged C versions for a good price. NOS pairs on the auction place.
Thanks for the input, Mr. M :)
Another masterpiece theater installment, thank you Doug! That amp sounds absolutely wonderful. I have been trying to purchase those Eurotubes bias meters ever since you demoed them a few moons back and they are still sold out! Very much hoping they return to market some day, being a much safer alternative to the shunting method that gives this particular amateur the heebies.
Thanks so much, DD. I really don't recommend the shunt method for PC measurement.....dangerous to mankind and equipment. Simply measure the voltage drop across each half winding of the OPT primary.
That’s for sure the best way to go
Those Eurotubes bias meters are fantastic. I bought mine a couple years back after watching Doug using them. Wonderful, wonderful tools.
@@SimonGotlieb Agreed, Simon. I don't know how I lived without them :)
Wow there is something airy in the background of the sound....really nice for the ears. As if you are outdoors.
Awesome video as always Uncle D! And I learn so much from this....
An interesting observation, PJ. I had a fan running, aimed at me, to make the 100+ degree workshop more bearable.
Thanks for another superb video.
Can't get a better education on amps than Uncle Doug!!!👍👍👍🎸🎸🎸🎸🎸
Wow....thanks, Doc :)
I love his amps
Me too.
Thanks, Nick. Our customers have only the best :)
The presence on the 5F4 is pretty enimic. Also it should be noted that when turning off the NFB loop, it will render the presence control inop.. but not sure it would matter that much as it is pretty useless. I placed a .47u Cap in place of the .1u on my presence control and it made a difference, at least you can tell it is actually doing something now. Great work as always Uncle Doug and we learned of yet another 6L6 variant.
Good observation about the consequences of turning off the NFB, DL, but really not very noticeable.....as you noted. Thanks so much.
Another great vid of a very neatly built amp. Always a pleasure to hear @uncledoug talking his way through it 👍
Glad you enjoyed it, Richard.
Hey Doug! I always enjoy the videos! I also have a Victoria 35310 (bandmaster clone). I picked mine up from an estate sale for $160 in need of a service. Now it sounds awesome! It’s from 1996.
Thanks, Aaron. What a great acquisition !!
Halfway through I'm thinking there must be something wrong with da guy's guitar or cables. I don't understand much of what you present but I love following your logical reasoning as you do your detective work.
Thanks, Choim. Glad you enjoy our videos.
I say one should have a couple of amps, guitars and cables just for troubleshooting. At least that's what I tell my wife :) thanks for the video!
That's a great tactic, Daniel, as well as a young Swedish female assistant to hand you the soldering iron.
That amp is built right...thanks for posting sir! Always appreciate your great attitude and knowledge!
Thanks for the input, Nick.
Hello again, Doug, with another excellent video, amp, and...what a gift!. I am searching for one of these cap testers for ages!. It seems to be difficult from here in Spain. And also: be very careful with the tester, because it outputs as much as 600 dc volts in the banana jacks. Never forget to discharge it, and put the test voltage knob at its minimum, because we need to see your videos during too many years! 8-) Thanks a lot, and God bless you, Doug & the cat gang.
Good to hear from you FW. Thanks for the safety tip :)
@@UncleDoug safety first, you know!
Almost all modern electronic equipment power supplies use a Line-to-Ground and Line-to-neutral cap as EMI/RFI filters. They are supposed to be a special XY rated safety caps that are designed to only fail open.
Thanks for the helpful input, William.
Well done with the cat! good for you!
Thanks, Jeff :)
Maybe a note of caution to our customer to double check the speakers
in what/where this amp calls home (?)
...and thanx for yet another wonderful vid
Thanks for the input, Jonny.
@@UncleDoug Thanx for the output UD... Wish I could get my ass out there to jam... Aah (>sigh
That Heathkit is a jewel! It's younger than my piece of Heathkit test equipment - I was given a Heathkit AQ-1 audio signal generator (circa 1957) by an old neighbor - and after a set of electrolytics, it's as solid as a rock (if you don't mind the analog frequency dial!) The head technician had a Heath cap checker similar to yours at one of the shops I worked for, and if he suspected a tech of shotgunning caps, he'd take it from the margarine tub and test it while the tech was away, then leave it on his bench with the results scribbled on a piece of paper. Needless to say, we mortals dare not step into his sanctum to test our own caps but he would break it out sometimes if we were stumped and he suspected leakage that we had missed. I wonder if someone has written a book about the whole Heathkit phenomonon - a real example of post war GI industriousness and excitement about the hi-fi craze. One thing I remember about Heathkits - when the owner was stumped by a problem, he'd bring his unit in with all of the encyclopedic manual, notes and records, and go over all of his prior troubleshooting in detail! I can't wait to see your future comparison video with the current magic box digital cap checkers. I use them, but don't completely trust them (how can a $15 ebay cap checker do the same job as the $450 B&K? circa 1975). Thanks for the great video, as usual!
Thanks for all the great comments and shared experiences, 87. So glad you enjoyed the video :)
Fran Blanche over at the Franlabs channel has quite a few video’s on Heathkit kits. Apparently she got started in electronics by visiting their repair facility as a child.
@@rivulus Thanks for the info, Roelof.
Very thoughtful and professional approach to the conclusion, I was thinking the whole time "why would victoria amps use orange drop signal caps in any fender clone amp they would build?" Victoria amps are normally built with the blue sprague signal caps that the victoria amp company commissioned sprauge to build to match the original fender offerings of the vintage leo fender designs.
Thanks for the nice comment and info, FL.
This amp was probably built back before Victoria commissioned the blue caps you mentioned. I have a early 90's guitar mag that showcased a couple tweed clones, a Holland, and a Victoria, both used the orange drops as coupling caps back then. In fact, I remember when OD were considered the best coupling cap... I have used several kinds in various builds, and I don't have a preference at this point. I have found that tubes and speakers make the most difference to my ears. That said, I believe I can hear a subtle difference between cap types, but I'm not sure if it's real or not. People argue about this to death. I'll leave it at that.
@@patchesthejaybird8431 Thanks for the info, PJ.
@@UncleDoug do you know the year of this amp?
@@fisheyelens876 I do not.....Sorry.
Your the best Uncle Doug thank you for sharing your noledge
Thanks, Sam :)
super interesting as always, Uncle Doug
Glad you enjoyed it, RJ.
Full credit to you Uncle Doug for the epiphany I had not too long ago drawing a parallel between bypass caps/switch pop caps and condensers in ignition distributor caps.
The parallel is a good one, Bass. Glad the video was helpful :)
Great video UD! Well worth the wait. In my version of a perfect world, I would watch Uncle Doug working on a vintage gem every week, amps n hotrods! And Elon Musk would open a vacuum tube factory in Texas... Thanks for doing all you do UD. Best wishes. FW.
I wish we had the time and energy to fulfill your dream, FW :) Elon has been hanging out in the workshop lately, pondering the Twitter buy. I'll ask him about some local tube amp factories.
@@UncleDoug Ha! I knew it!
Wouldn't take much to retool the back half of the Cool Whip factory just to get some tube production amped up... ;)
@@fullwaverecked.....and a nice supply of Cool Whip to boot. Win......win !!
@@UncleDoug That reminds me, I've got to pick some up for dinner. Thanks UD! Cheers!
UD Time! LayZBoys extended and beer is loaded. Thanks for the video again UD! (I really wish they would sell LayZBoys here in Europe)
It sounds like you will be ready for our next video, K. Keep the beer and recliner handy......you'll need it.
Nice explanation!👍👍
Thanks :)
Wow My first Stratocaster Ibanez 1976 Silver Series...Great guitar..And My first Ap was a Super Reverb 45 Watt 1972!...I'm going out to buy a lottery ticket!
You're on a winning streak, Ratta.
Nice job Doug
Thanks, Dan :)
What a beautifully wired amp 👌🏻Definitely not built by the hack master next door 😆. Nice work as usual UD .
Thanks, Stewart. It really is well done :)
I look so forward to your videos I understand more about sound because of you and it's the truth.....
That's great to hear, Charles :)
Nice video, good playing at the end.
Thanks twice, MR.
This is a great video on the troubleshooting process for the power section, and is the one I ended up following to debug my DC30 clone build after trying some less effective processes.
Thanks, Jason. It was our intention to provide a rational approach to the testing procedure.
@jason Doherty, how did I know I'd find you here LOL =p
@@KorbenDenver Hi buddy!
Another Uncle Doug video, sweet!🤘
Hope you enjoy it, MJ.
A sterling effort uncle doug brilliant ! and a welcome gem of
entertainment as usual, `when something`s not right its wrong`
as bob dylan once sang, your chanel is always right as rain !
Wow....thanks so much, William :)
A new Uncle Doug video is an event!
Hope you like it, Ernest :)
UD, outstanding as usual. The tube swaps are funny, you have to restrict the amps to the tubes so you don't damage the power amp, so now the tubes are barely working, it's like someone I knew, tunnel ram, twin 1050 dominators, on a stock 327 in a Camaro, just "couldn't get it to start right in the morning, and had to rev it too high at stop lights", but it looked great. Also when I heard you say Hammond my ears perked up like a Dobie hearing 15 kHz, but my hopes were dashed when I realized you were talking about a transformer. Anyway hope everything continues to go well for you, and still hoping someone sends you a 144 or 147 amp to repair.
The Blue Mule
🤘 Leslies Rule 🤘
Your analogy was right on the money, BM. Thanks for your input :)
These videos are such a great resource. Thank you for all your hard work and help! It is extremely helpful for anyone working on amps!
That's great to hear, Max. Thanks !!
Great respect as always. Those Victoria's look so nice!sound good with your care.
Thanks so much, SS :)
I came for the nerdy amp talk, but stayed for the oak tree scandal and shop cat narrative. 🐈
We're glad you joined us, Mark. You're always welcome :)
Love your channel, keep em videos rolling 👍🏽👍🏽👍🏽
Thank you! Will do!
I built a clone of this circuit myself a few years ago. I used Mercury inductors throughout, and I found it hit the bias numbers in the schematic just about exactly. I think I ended up with 410-420 V on the anodes at about -20 V on the grids, and that it was in its happy place there at ~ 60-70% for a pair of 5881s.
Sounds like excellent values, BS :)