HOT TRANNY Leads to Confusion and Poking with Stick - Stromberg-Carlson SAU-22 Conversion
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- Опубліковано 7 вер 2024
- In this video, we'll revisit the 1960 Stromberg-Carlson SAU-22 PA Amp. We'll tinker some more with the circuit, changing the Master Volume we installed in the last video. We'll look at a couple more types of Master Volume control to add to amps with a cathodyne phase inverter, both pre-phase inverter and post-phase inverter, including a Ken Fischer PPIMV from the Trainwreck Pages. Then we'll troubleshoot some noise issues, replace some tubes and resistors, and then finally figure out what's making the power transformer run so HOT - hot enough to fry eggs! Many of these same mods shown here would work with 6V6, 6L6, EL34 and EL84 output amplifiers as long as they were cathode biased, push-pull amps with cathodyne phase inverters.
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How do you rule so much so often? Guitologist rules!
"Girls will be boys, and boys will be girls
It's a mixed-up, muddled-up, shook-up world
Except for Lola, lo lo lo lo Lola"
How prophetic those words.
Or Lou Reed's song.
Getting past the obvious 'clickbait' in the title my impression is that this made a very sweet sounding amp. It is always hard to tell what things sound like on UA-cam because there are so many variables involved but I really liked the tone of this amp when you were done with it.
Can't wait to see what youtube adds to my recommended videos after adding this one to my history.
Sorry that thing gave you so much trouble.I bought those jjs about 2 months before i sent it to you. I won’t make that mistake again. Ps thanks for not including “hot tranny service” on the invoice... not sure how i would’ve explained that one to my wife.
Just explain to her you're trying to spice up the marriage. :P
Hahahahahaha
Looks like it was worth the trouble. We got a couple cool vids out of it and you get a pretty cool amp back. I especially liked the clean tone, really warm and delicious.
Lol
Based on the original voltages and cathode resistor value, I think you were stressing those JJ tubes beyond their operating limits...so I would not be quick to blame the JJ tubes as being bad but rather they were stressed and any tube would suffer premature failure under those conditions. I use that brand a lot and have not noted any quality issue when treated within spec, just sayin'.
sounds pretty good man, i like watching your videos, the trouble shooting, etc. im a newbie when it comes to fooling around with tube amps and your videos help me out a bit, thanks
Wow, the cooler biased EL84s sound great. I have a couple of builds I will try this tomorrow on. I have never taken the cathode resistors above 390 ohm but this made such a difference in the tone and still breaks up very nice. Im getting around the same plate voltage on one of my builds so will change it out and be in the same range. I have some 470 ohm resistors in my box I will try out. The cleans sounded so good and crank the master down and gain up and does what its supposed to do. Most guys always bias these cathode biased power tubes hot including me but this demo will change my mind for sure. Great job
Great playing Brad,love you and Steve from Boston.Love shitpost Friday.Keep those great videos coming.
I've never clicked so fast in my young, confused life.
Big Snoops
🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
That title took me back to my college days... Frats used to really haze back in the day lol... cool video as always Brad.
Great Video, Brad !
You always do the Best Investiagtive Diagnostics.
Great use of schematics, work the problem, et cetera and so forth !
Thanks, Brad, For All That You Do !
This title is an interesting one to be displayed at work. Good thing my monitor faces away from the door. :-D
Bet that title had your mother worried.
Darn impressive Brad, I had no idea you were that good a guitarist man, BRAVO! What a beautiful tone from that amp, cab and guitar. Play on my friend.
This is the most epic video title I've seen in a long time
Thanks for going into depth on the master volume. Great learning there. I've used Rob Robinette's website a lot to help learn my 5E3 clone, bias it and mod it. His info on the grounding scheme on the 5F1 was invaluable when I was building that kit, along with Uncle Doug's scratch build 5F1 (adjustable NFB and switchable speaker jack). Ordered one of those Transistor/Capacitor/ESR meters through your banggood link, those are looking more and more handy the more I dive into amp circuits. Got my variac and some stuff following the amazon links a while back, but never can tell if that stuff works
you won best video title of the day!
just wanted to say i've been learning a lot watching your videos, thanks
Hey brad, just some ideas from my site.
Not quiet sure, which value you have chosen for the pot now but i do imagine that this solution loads the PI way to hard and debalances the whole PI stage, as site effect you won't drive both output tubes correctly (Pure theory).
If you load the Cathodyne too hard, you reach a point, where the cathode voltage gets clamped while the anode gain increases extremely, the system debalances itself incontrollable compared to a long tail PI. This also happens by loading the CD with signal cancelling on a virtual reference.
A probably good value of loading a CD should be way higher than the anode resistor since it represents roughly the ouput impedance of the CD Anode-Output.
My personal preference for small amps like this would be to go for a PPIMV dual pot with around 500k to 1Meg. Since the poweramp is selfbiasing, you could easily implement it directly between the PI and the output Tubes.
I probably would have de-farted the whole amp by chosing smaller coupling between the stages but thats for sure personal preference also. Just watched this one with my laptop speakers.
Cheers and thanks for your videos, hopefully this doesn't apply liberally, my english is way limited.
0:04 - Kudos to whoever whipped out that graph at the beginning of the video. FINALLY a precise and proper curriculum vitae of The Guitologist. ad title: some Prometheus is tempting the YT-gods, it seems :)
Fuck 'em. They aren't showing my new vids to all my subs anyway. Maybe if they treat people better we'll be more willing to play ball.
Absolutely right. Idiocy at YT comes in phases and we're at the start of another one, it seems. They censor your streams on the fly, another youtuber got a strike for having the word "hate" in the title and meanwhile only Gandalf himself knows what videos are eligible for monetization. Screw them.
7:13... correct term is ‘common mode cancelation’.. you got the gist of it perfectly👍
On my SAU-22, the transformer also gets pretty hot. Uncomfortable to touch for more than a few seconds after the amp has been running for an hour or so, but I'm not too worried after running it for a couple of years now. It's common on some amps. I had mentioned in my previous comment that I put a resistor in series with the primary to cut the voltage down to about 115. This helped the high plate/screen voltage (375V in reference to the cathode, absolutely killed tubes, especially JJs which lasted like 6 months) and high filament voltage. Before that, I was also forced to bias to like 70% with a pretty high cathode resistor. Now I use a low value, probably 120 ohm, and bias to 100%. The 400 volts B+ in this one is scary, way high for an el84 amp.
No surprise about the 6U8. Those things are microphonic nightmares. Even the NOS one I got was bad. That's why I had switched mine to a 12ax7.
The new posy-phase inverter control is cool! Comparable to a a Vox cut control, which is an amazing feature.
good 'un good 'un I have another small voice of music amp, and it's transformer also gets hot. Neither burn you instantly, so I'm sure the copper and iron doesn't mind much. This is how hot they have run since 1959. They're reading at or slightly below their power consumption.
As far as the tubes go, yeah, I've heard people say that the old ones could take the abuse, and while I'm sure some could, ive also heard people say the exact opposite. I know of cases where only certain modern EL84 tubes would work in amps because certain NOS ones would redplate. 7189 can help for sure, definitely a good choice if your el84 amp kills tubes. I wanted mine to accept any EL84 tube I stick in it though, and the current set, Sovtek, have been going strong for a year and a half now. Before lowering the voltages, it killed JJs in about 6-7 months and a set of Tung-Sols in 11 months.
"Hot tranny leads to confusion"...I think I read that thread on 4chan and it made me very sad and slightly angry.
Now that's a head of a headline 😃
Awesome !!! A Master V-Tone Mod. Never seen that. Seen a bleed resister on a MV, but I think you just did something new. I would have just slapped a Rheostat after the amp for a power soak . But your idea seems to work and thats all that matters .
Great playing..
Amazing sounding amp!! You ended up with a mix of presence, tone and master volume! Trying a stereo pot for each phase or modify even more like a 2204 1969 Marshall master vol could be options to experiment for futures amps, i think. Anyway great job!
Comparing sound demos between your 2 related videos regarding this amp, I'd have to say the amp sounded better over all in the first video...
That title is hilarious!
Watching you troubleshoot is like watching Bob Ross - not sure why you are are watching but intrigued nonetheless. Being a Nuclear Electronics Technician in the Navy and into guitar effects - I can lose time watching your channel.
Thanks so much for watching, Dennis. I appreciate it. Did you work on subs in the Navy?
Aircraft Carriers
Not so much “criticism” as a tip to learn more theory and do it better. Great follow up👍🏻.
I appreciated your comment very much. I had already had some reservations about it, but knew the current across the pot would be very low and the thing would work, if not perfectly. But I think it's better now, so thanks!
The Guitologist thank you👍.
Where are the high-heels, makeup hahaha, another interesting video and ending with your guitar solo
Hey Brad, I just had to let you know how great I thought this turned out, the sound really was impressive all the time you were playing but especially at the beginning. That was really a crystal sound that was perfect with the Tele. I don’t remember you saying but did you send that amp home after the first repair or was this a continuation of the first video? It was another great learning video, thanks! Buddy
LOVE THE TITLE
Just wondering if the hot tranny isn't quite up to the job? I think your work has brought the current demands down to a level with which it is much happier. As to possible search for noisy resistors, just get a signal tracer with a noise function, I have a Heathkit T-3, this will find noisy resistors quite quickly. Mr. Carlson demonstrated this very well. Thank you for showing all your work, your posts are very good teaching.
Exact issue with an amp I just built. I also at first suspected it was a leaky coupling cap coming out of the phase inverter. Ended up being bad a JJ el84.
No shit? Must be a bad batch out there.
Best title yet!
It was a death sentence for the success of the video. Got about half the number of hits I usually get on a video like this.
Sounded nice.
I met her on the bench, down in LOU ky, she had some oscillations that could heat up iron like a poker, p-o-k-e poke her. I thought about a snubber but I'm not that kind of lover so I cooled her down with a can of cool cherry cola, c-o-l-a cola....
Holly came from Miami F-L-A, hitchhiked her way across the USA, shaved her legs on the way, plucked her eyebrows and he was a she, I said hey babe, take a walk on the wild side, I said hey sugar, take a walk on the wild side, and the colored girls go , Doot ti doot, di doot, doot ti doot doot.
Best vid title evr
Click bait? ...I thought we were going to see a cross dresser being poked with a broom stick!!! Just kidding couldn't pass that one up...Great information...very good video
Hey Brad, another easy fix (sarcasm). You earned a day off brother. Enjoy!
Don’t feel bad about the brand new cap being leaky... Things have gotten so bad that we now do 100 percent testing of all capacitors upon arrival. It seems a huge time waster when sifting through hundreds of parts... boring, but finding the increasing number of duds in advance of production saves an immense amount of time later. 20 years ago and before, we never got bad parts.. now its fairly common to have 1 out of 100 or 200 be faulty. At this time only Rifa poly and Vishay AC power rated caps are fault free. Every other brand we are finding duds. We also do high tolerance testing for other manufacturers and find similar percents of duds or out of spec in customer parts batches.
Just in case you didn't see it, the cap was fine. Tube was bad. Still have spotless record with these caps...so far.
the master volume pot is a linear taper. Swap it out and put in a audio taper.
would the AC adapter that is in the amp possibly introduce some type of noise interference into the signal chain? I only ask because Wampler showed on a video the difference between a pedal powered by a high quality adapter and powering the same pedal with a cheap adapter. I would expect that finding a way to hard wire the lights into the amp without using the transformer would be a better idea.
The adapter is being powered off the primary wall voltage. So it's isolated from the power being supplied to the rest of the amp. It could still induce noise if too close to signal wires, but that didn't seem to be happening in this case.
You know something Brad? I really think you are catching on to this whole UA-cam thing.
Funny little amp - it looks like a gallien krueger and sounds like an old fenton weil.
Any master volume is just going to give you preamp distortion only. Some work better than others depending on the circuit and type of PI. But you will never get the sweet harmonics of output tube distortion with any of them. The cold clipper gain stage of a modern high gain Marshall comes close; but I prefer the use of a reactive load attenuator.
Guess what my "Recommended For You" videos popped up?
Hey Brad. Great vids! Thank you for the tutorials. I just wondered if there is a temperature at which you would definitely change the PT. I find they become uncomfortable to handle at around 125 degrees f, but it's hard to find consensus on when they become hazardous. Thanks again.
IT'S A TRAP!
dat title says it all.
cleans up real nice Brad
Can you please post a revised schematic for this amp? I have a 1962 SC Signet 22, and would like to get similar results (nice bedroom level overdrive, and ability to crank it if need be). I'd also like to add a dedicated on-off toggle, and a real TMB tone stack. Too MUCH? Thanks.
Uncle Doug says it should have been an adjustable negative feedback loop....
It’s more of a tone knob cause you done MESSED UP, son!! Nah…just kidding,man! It DO sound awesome,Mr Linzy!! Sir Brad Linzy of the Clan, Linzy! Need a coat of arms with crossed tele & PRS,a soldering iron with a quillon on the handle and a tweed twin amp! Sorry, I’m artificially happy ,tonight! 😄
Question how did you for from 'slightly hot, I can leave my hand on it.." 29:33 and then you said 40:47 "It was really smokin, You can't leave your hands on it, you can cook eggs on it"
I jammed through it for about 20 minutes and that's when I noticed the excessive heat.
The Guitologist ah ok that explains it. Good work and good fix. Thanks for creating these videos I always learn from your videos.. thanks again
Thanks for the comment! I did sorta skip that explanation.
Brad, shouldn't that master volume pot be of the "audio taper" type? I think it would give you more of a range control concerning volume.
I think Friedman was saying he has had a lot of issue with JJ tubes as well.
I have never had issues like this with ones I order from Antique Electronic Supply/CE Distribution. The problems I've seen of late have been on customer amps who ordered their tubes from god knows where.
If all the naam demo guys played like you, it would be much less boring to watch naam videos.
You do very good work. I'd like to let you know about something. In drafting or hobby stores they make labeling decals that will match the original lables.
You had me at “poke”! 😁
Is that pot linear or log/reverse log tapered? Trying different tapers to match the most useful range has worked for me in the past to get finer control. It's sometimes counterintuitive what works best, to me anyway. Pretty sure you'll already have thought about this though!
I came here to say much the same thing. That's the whole reason for the different taper is to spread the action out over the range of motion.
@good 'un : Nice idea! I have heard of people taking dual pots and customising them, taking tapers from different pots and retro-fitting them. An addled brain has never done any harm to creative thought!
you may have tried rewiring the flux capacitor so that the positive ions go the opposite direction , that should fix the volume issue
Would using a linear instead of a logarithmic pot or visa-versa help with the all or nothing jump that's heard?
It would change the behavior, yes.
damn Brad, with your guitar playing how come you're not a rock star?
What speak/cab are you playing that through? I think your tune reminds me of Pixies. Work it up into something...it's really good.
The cab is a M80 Fender cab from the late 1980s or early 1990s. I think it has Eminence drivers.
Had to make sure I hadn't gone to RedTube.
Careful yo. I hear tell they can poke back...
Couldn't actually see any transistors in the circuit there, so yes, that is indeed confusing.
Are you using a linear or audio taper pot?
I've seen a lot of guitar kit build videos lately that recommend shielding the body cavity with foil. Either aluminum or copper foil throughout. Including pickups, controls, wiring channels and pickguards where pickups and controls are mounted. Does this really help noise cancellation? Or is most noise created in the amplifier? I know single coil pickups are notorious for noises, squeaks and squeals of all types. But would humbuckers benefit as well? If at all?
You won't regret shielding, you'll only regret not doing it.
obrigado por estas dicas valiosas
A bad JJ strikes again!
Yep. It's been a rash lately.
I've been building and tinkering with amps for over 20 years now and never had much luck with JJ tubes. Good thing there's better alternatives out there.
Fine job on the amp BTW.
To be fair they are the cheapest tubes one can buy now (well in europe anyways) cheaper than Chinese shuguang. I think that they've been cutting many corners lately... Very inconsistent
I build a lot of tube amps and mostly use JJ which are great tone tubes. I try others but go back to JJ. Had a rash of GZ34/5AR4 JJ rectifier tubes go bad so changed to Sovtek rectifier tubes.
They suck to put it bluntly.
This title sounds like a story depicting a night witha bottle (or 2) of tequila.
Interesting video, as always. I've got a "hot tranny" as well - on my 2x EL84 "Knutsen-Amp" that I restored and modified. Gotta try cooling down the bias a bit with a higher-value cathode resistor, as it's currently at ~88% plate dissipation and could probably go lower. But I'll have to check the voltages first as the power tubes are JJ.
PS: Your Tele is nearly a semitone sharp, which bugs me as I have *actual* perfect pitch ;-)
I rarely even tune the thing. I'm lazy about tuning on these videos. I just pick it up and jam. If I hear a string that's out a little, I try to skip it. :D
Thats one of the best sounding amps you've done to my ears.
Btw what's the tune you play at the end...sounds familiar
Don't know. Just making stuff up.
It reminded me of Victim of Changes there for a sec.
Hey Brad,
Out of dumb curiosity, was that amp used prior to something else, say, a projection amplifier Maybe?
I'm no expert on amplifiers, but something feels off about that amp. There could be a possibility that amplifier, might have been used as a vocal amp as well.
Could that have been used as a vocal amp and not a guitar amp?
It was a PA.
What might make a power tranny hum, and slightly vibrate? JCM 2000 TSL 60. It has a slight audible hum and you can feel it a little bit when you touch it.
Bad ground connections, ground loops, loose transformer laminations or failing/loose transformer windings internally. Could also be a wrongly oriented transformer with relation to a nearby OT or other source of magnetic flux.
Its used and it pretty much did it from day one. I swear though it didnt start until I changed tubes and re biased it. I put the old tubes back and it still did it. I think I need to open it back up and check around again.
Dont these models have some known tranny issues?
What is that meter on top of your variac?
ua-cam.com/video/2mrlha-uzro/v-deo.html
Brad, I love the title. Some UA-cam Algorithm or is it Trigger-word fuckery!
Just screwing around. See how long it takes the trigger brigade to either demonetize or send it into obscurity algorithmically.
the wallwart transformer inside the case makes me cringe, i know it works and ive seen it before, but i dont like it :D
Isn't it just for the leds?
Side note- goo gone works great as a bong cleaner.
It appears as though this feature (master volume) is getting flak because it really isnt a master volume.... Its a terrible imposter, of what could have been a nice master volume...
Are people avoiding this cause the title offends them or because they actually think you're gonna show 'em something not permitted on here, either way sounds pretty dumb to me. Also fwiw I'm trans and had a good chuckle over the title, I'm as well an amp tech and no stranger to that joke lol. I think people are just too flipping sensitive on both sides of the coin lol.
Also also I get JJ's through CE all the time! and have had very few bad eggs, maybe 1 out of 100.
You're awesome! May I ask...what's the deal with techs and being trans? There are at least two or three others I know of on YT.
Idk cuties? lol
I will never buy another JJ tube again. A nasty EL84 turned my Carvin Bel Air into an end table/foot rest. It toasted two of the traces on one of my circuit boards and now since Carvin is defunct there are no replacement parts to be had. JJ...no way.
You can fix it. Just rebuild the traces with wire.
I looked at it. Parts of the board are actually cratered plus I'm not sure what other damages were done. One of these days I'll look at it again...or I'll send it to you.
Just put a 1M ohm pot across the grids of the the output tubes. Tie the center and one side of the pot to pins 2 on the output tube sockets.
Oh sorry, as soon as I wrote that, you put up a schematic that showed that very thing. Too funny.
Happens a lot in comments, but just shows you were on your toes. :D
You couldn’t have chosen a better title?
Hey man I live in northern New York I recently purchased a 48-1264 Philco and cannot find anyone to work on it. Let me know what u think.
Not something I can take in right now. Too covered up.
Signal comes thru the phonograph but I cannot get the radio to work any suggestions?
Lol at the title!!
Wtf this isn't porn hub?!?!?... I mean .. Uh .. I'm Str8 and here to learn about amp. Repair ...
Misleading title. Video content not what I was expecting.
Jamie Bales Well there's always suicide.
What about Svetlana Vacuum tubes.
Svetlana winged C are the closest tube there is to RCA black plate 6l6's. Not the regular Svetlanas, they are just Sovteks. I have a quartet of Winged C's in my Twin, and love them.
I was waiting fer the girl with something extra....
First!
Not wise to run the shit like that....That one on the Stealth got hotter than hell after trying a bunch of shit....
HAHAHA, don't stick your probe on the grid! LOL LOL Hebrew joke, not judaic, we'll talk about that another time!
OK not any of those things joke, but I figured you'd appreciate that!
Hahaha