I've never pulled or replaced preamp tubes while the amp was still on, but I guess it's really no different than flipping a switch. It's funny how we sometimes never question rules because they were presented to us as gospel.
Crazy how sometimes when we're playing at home, or depending on our gear for a rehearsal or something, these issues seem like the end of the world sometimes, but the solution here took nothing more than just switching out some tubes to see what the problem is. I'm learning to be patient with valve amps. I'm understanding it's part of the charm. Their little ways they can fail. Great video!
I have an AC15C1X. I got improved dynamics after improving the cabling from OPT to speaker. I soldered the speaker terminals and did ring crimp terminals in the middle (screw, pressure washer, nut). This assures very low Z on speaker side which provides a more reliable reflected Z to the output tubes.
Been watching your videos for about three days,really enjoy the content.Looking forward to the next video. I think you’re in Memphis, I was up there in 2019,for a visit,enjoyed the hell out the city,only about a 3 1/2 hour drive from birmingham.Stayed at The Arrive Hotel,cool place,looking forward to coming back,soon.
Love the way you talk us through your work in these amps. I just wish you were in Australia so I could bring my Fender Supersonic 60 combo to you to take a look at. The reverb has been problematic for me. Had a two different techs look at it. Replaced the tank with a MOD tank and I still have issues with the reverb cutting out and being ineffective. Not expecting you to solve that issue. I just turn the reverb off now and use the amp without internal verb.
Lyle when i dropped off my amp I also gave you I think 5 new Mesa 12AX7 preamp tubes. You can use them If you can't get any. I know they're Sovtek tubes. Which do not do well cathode following. Which my amp does. So kind of useless for me in some positions.
As usual, awesome work, canny, and perceptive. Question: is it possible to add more 12ax7's, in a cascaded configuration, and turn a vox into a more capable high gain amplifier? Most people complain that EL84 power tubes don't really sound good for that purpose, but I've stuck my neck out and said that preamp gain is the real issue, not power amp gain. But when I research EL84 tube amplifiers, I find that they are not often paired with high gain affairs, which leads to my next question. Question #2: can a vox amp be switched to EL34 or 6L6 output tubes, and does that necessitate a different output transformer and other parts to make it work properly, as well as a new tone stack and voicing to make it a credible swap?
Hi! Not sure if you reply to old videos (!) but at ~3:19 you mention the scratchy sound from the guitar's volume pot is due to "DC present at the input" which could be a bad preamp tube (if I'm understanding you correctly). How are you able to differentiate that vs. the issue being a bad/noisy volume pot that might just need some DeoxIT (or a replacement pot)? And thank you for this channel, your videos are a wealth of information for a budding tinkerer (and future amp "improver" haha)-you're awesome!
Thanks man. If the guitar doesn’t have that issue with other amps, and all guitars have that issue with this amp… I can also measure DC on the input grid. But the guitar volume pot lets me know it’s there to be measured.
I should send my Mesa TA30 to you.. I sent it to 2 different techs plus the Mesa factory and the problem it has still isn’t solved and it’s not obvious unless you spend time with the amp. It has this power stuttering that it does where the amp pops off and on. The power supply and a few transistors have been changed but the problem is still there. Swapped tubes out and all and still the same problem. Idk.. it’s a crazy amp
You said the scratchy volume pot on the guitar is a symptom of DC on the input? My TBX currently does this. I'll have to try swapping out a new pre into v8. Are there any other possible causes that don't require a tech? Always interested in learning from you. Thanks. Oh yea, and aren't the first two channels out of phase with the brilliant? Could that be a cause of the customer's dark tone?
They are out of phase but the cancellation just gives a mid scoop. It was dark here because the triode used by the TB input had DC on the grid, preventing it from biasing correctly. DC on the guitar would be the tube, the 68K grid stoppers, or the 1M grid leak in descending order of likelihood.
@@PsionicAudio that makes sense. I've heard some players liken the jumped cleans to a blackface fender. I'm going to try that out again with a twin cabinet just to hear it. Thanks again for the info!
Not saying this was the case for this customer, but oh how I dislike the "I just want it gone" tantrums I have here in the shop from time to time. Sometimes things need further refinement after the fact, whatever, let's just get it done, eh?
It's funny.. I hear a lot of people having issues with the TBX. I had mine for going on ten years and never missed a beat. Traded on a Matchless DC-30... not my wisest move.
Normal. Some amps have an inrush limiter to prevent that at cold turn-on, but otherwise all the heaters bright-up for a half second or so at power-on. Completely normal, tubes are good for it.
@@edwardleaver7838 , many, not all, 12A[ ]7 family tubes were designed to heat extra-quickly to prevent heater burnout when the tubes were used in series-string circuits; old TV's and table radios often had series string heater arrangements, with all the tube heaters in series and the total heater voltage of all the tubes together adding up to the line voltage from the wall outlet. If some tubes heated at different rates, heater failures were more likely.
wait you can swap out pre-amp tubes with the amp on? If thats safe on all amps, please let me know, I love swapping pre's but its such a hassle as I do complete shutdowns. Thank you!
Don't hot swap cathode followers (I didn't here) and you don't want to hot swap if it makes a big pop that can be hard on speakers. Maybe I should have discussed it or just not done it on camera, as I know when/where it's safe.
@@PsionicAudio Fair enough. I will stay in my lane and keep safe. I actually just e-mailed you about a project. Look forward to your reply. Thanks so much for this reply as well.
No, never a problem. Though only the JMIs, some '70s models, and the TBX have the channels of of phase in stock form. HW, CC, and Custom all have them in-phase stock.
iI am not surprised here, in my experience JJ tubes suck sound very flat and lifeless when they work at all no charge you are a great guy!! someone else would have sold him the RCA tube for at least $100 right now!!
Dude, go to a TV repair shop and pay 15 bucks for any 12ax7 they have in stock. I have every brand of "cool" and paid the same as new production. People overcharging for "mojo" are terrible.
Hello Sir, I e-mailed you about my AC 30 Looking for price and turnaround time. I know your busy but please let me know if you accepting work. Thanks for sharing your hard earned knowledge.
I've always heard the TBX AC30's were not built as good as the later AC30's that came after. I'm guessing they are referring to the layout and design etc. But I have played many TBX AC30's and they always sound better than the later redeisgned AC30's to my ears. Some better than others but better than the AC30's tone wise that came after the TBX models. I'm not sure why. Maybe you know something about this? Maybe because the TBX had Made in England Alnico blues and the the AC30's that came after the TBX had the Chinese made Alnico Blues?
There hasn't been an AC30 since '69 that has it right out of the box. All of them need tweaks/improvements. The TBX has built-in ground loops and was over filtered. The CC preamp is set too clean, the loop has a factory error (easily fixed but still) and it has shiny grill cloth. The Heritage was a terrible unreliable joke where the PCB solder joints can't hear the weight of the turrets. The HW is over filtered and the cheap ceramics and iffy solder can make things harsh. The Custom has a bit too much gain, is over filtered, and there can be arcing due to trace proximity on the output tube board. All these things are fixable. I'm not impressed by any of them in stock form. The Custom costs the least to be made into a real AC30. About two years ago I did a video comparing the TBX, the HW, and the Custom, all after getting my JMI+ mods.
I suspect the owner just had a bad taste in his mouth after paying for the upgrade. Kinds like having an infidēlis mate that you used to love. Trust must be re-learned!
![Robben Ford & His Dumble Overdrive Special [He Plays It, We Play It!]](http://i.ytimg.com/vi/4z-IkXE36DI/mqdefault.jpg)
No specific comment, other than to say thank you for all your work in producing these videos. I learn something new from each one.
More i watch this channel more i don't know what to buy.
My fav you tube channel. Thank you sir.
I've never pulled or replaced preamp tubes while the amp was still on, but I guess it's really no different than flipping a switch. It's funny how we sometimes never question rules because they were presented to us as gospel.
Such a relief to have competent tech who is entertaining and not bitter
I'm glad I've hoarded every single preamp tube I've ever owned. Perhaps I can trade a couple Siemens ECC83s for some lumber and a tank of gas.
Crazy how sometimes when we're playing at home, or depending on our gear for a rehearsal or something, these issues seem like the end of the world sometimes, but the solution here took nothing more than just switching out some tubes to see what the problem is. I'm learning to be patient with valve amps. I'm understanding it's part of the charm. Their little ways they can fail.
Great video!
That was really good that! You know these old tube amps inside out. Thanks for your time!
I have an AC15C1X. I got improved dynamics after improving the cabling from OPT to speaker. I soldered the speaker terminals and did ring crimp terminals in the middle (screw, pressure washer, nut). This assures very low Z on speaker side which provides a more reliable reflected Z to the output tubes.
It was good to hear you get your Floyd on👍. Amp sounds great as always.
Been watching your videos for about three days,really enjoy the content.Looking forward to the next video. I think you’re in Memphis, I was up there in 2019,for a visit,enjoyed the hell out the city,only about a 3 1/2 hour drive from birmingham.Stayed at The Arrive Hotel,cool place,looking forward to coming back,soon.
Love the way you talk us through your work in these amps. I just wish you were in Australia so I could bring my Fender Supersonic 60 combo to you to take a look at. The reverb has been problematic for me. Had a two different techs look at it. Replaced the tank with a MOD tank and I still have issues with the reverb cutting out and being ineffective. Not expecting you to solve that issue. I just turn the reverb off now and use the amp without internal verb.
Good work isn't cheap, and cheap work is rarely good!
Lyle when i dropped off my amp I also gave you I think 5 new Mesa 12AX7 preamp tubes. You can use them If you can't get any. I know they're Sovtek tubes. Which do not do well cathode following. Which my amp does. So kind of useless for me in some positions.
As usual, awesome work, canny, and perceptive.
Question: is it possible to add more 12ax7's, in a cascaded configuration, and turn a vox into a more capable high gain amplifier? Most people complain that EL84 power tubes don't really sound good for that purpose, but I've stuck my neck out and said that preamp gain is the real issue, not power amp gain. But when I research EL84 tube amplifiers, I find that they are not often paired with high gain affairs, which leads to my next question.
Question #2: can a vox amp be switched to EL34 or 6L6 output tubes, and does that necessitate a different output transformer and other parts to make it work properly, as well as a new tone stack and voicing to make it a credible swap?
That RCA sounded beefier bringing up the level nicely. I love seeing the easy fix.
You can "get yer Floyd on" any time/way you like, even if it's in "Arnold Layne" style ---- we're not judgemental ! 😁
did that chinese tube have heater flash?
Is there a way to make the Vib/Trem channel volume louder? I notice it’s much quieter than the other two channels.
Hi! Not sure if you reply to old videos (!) but at ~3:19 you mention the scratchy sound from the guitar's volume pot is due to "DC present at the input" which could be a bad preamp tube (if I'm understanding you correctly). How are you able to differentiate that vs. the issue being a bad/noisy volume pot that might just need some DeoxIT (or a replacement pot)? And thank you for this channel, your videos are a wealth of information for a budding tinkerer (and future amp "improver" haha)-you're awesome!
Thanks man. If the guitar doesn’t have that issue with other amps, and all guitars have that issue with this amp…
I can also measure DC on the input grid. But the guitar volume pot lets me know it’s there to be measured.
I should send my Mesa TA30 to you.. I sent it to 2 different techs plus the Mesa factory and the problem it has still isn’t solved and it’s not obvious unless you spend time with the amp. It has this power stuttering that it does where the amp pops off and on. The power supply and a few transistors have been changed but the problem is still there. Swapped tubes out and all and still the same problem. Idk.. it’s a crazy amp
How does a tube put DC on the input?
Great info on this
How do you get that twin tone?
Thanks!
th-cam.com/video/b6GpOlRj8bw/w-d-xo.html
You said the scratchy volume pot on the guitar is a symptom of DC on the input? My TBX currently does this. I'll have to try swapping out a new pre into v8. Are there any other possible causes that don't require a tech? Always interested in learning from you. Thanks.
Oh yea, and aren't the first two channels out of phase with the brilliant? Could that be a cause of the customer's dark tone?
They are out of phase but the cancellation just gives a mid scoop. It was dark here because the triode used by the TB input had DC on the grid, preventing it from biasing correctly.
DC on the guitar would be the tube, the 68K grid stoppers, or the 1M grid leak in descending order of likelihood.
@@PsionicAudio that makes sense. I've heard some players liken the jumped cleans to a blackface fender. I'm going to try that out again with a twin cabinet just to hear it. Thanks again for the info!
Do you ever work on Mesa amps? I'm curious to know about build quality
I have almost 700 videos on here. Many Mesas await you. ;)
Not saying this was the case for this customer, but oh how I dislike the "I just want it gone" tantrums I have here in the shop from time to time.
Sometimes things need further refinement after the fact, whatever, let's just get it done, eh?
Like spark plugs :)
nothing like throwing hundreds of dollars at a problem , but that earns you the right to attack people in comment sections who do not use tube amps .
It's funny.. I hear a lot of people having issues with the TBX. I had mine for going on ten years and never missed a beat. Traded on a Matchless DC-30... not my wisest move.
there was quite a bit of bright light when you were hot-switching that preamp tube....
Normal. Some amps have an inrush limiter to prevent that at cold turn-on, but otherwise all the heaters bright-up for a half second or so at power-on. Completely normal, tubes are good for it.
@@edwardleaver7838 , many, not all, 12A[ ]7 family tubes were designed to heat extra-quickly to prevent heater burnout when the tubes were used in series-string circuits; old TV's and table radios often had series string heater arrangements, with all the tube heaters in series and the total heater voltage of all the tubes together adding up to the line voltage from the wall outlet. If some tubes heated at different rates, heater failures were more likely.
wait you can swap out pre-amp tubes with the amp on? If thats safe on all amps, please let me know, I love swapping pre's but its such a hassle as I do complete shutdowns. Thank you!
Don't hot swap cathode followers (I didn't here) and you don't want to hot swap if it makes a big pop that can be hard on speakers. Maybe I should have discussed it or just not done it on camera, as I know when/where it's safe.
@@PsionicAudio Fair enough. I will stay in my lane and keep safe. I actually just e-mailed you about a project. Look forward to your reply. Thanks so much for this reply as well.
@@PsionicAudio thanks for that! I didn't know you shouldn't hot swap a cathode follower
Are there Vox models that the channels are out of phase that cause problems when jumpered like some Fenders? That was my first wrong guess.
No, never a problem. Though only the JMIs, some '70s models, and the TBX have the channels of of phase in stock form. HW, CC, and Custom all have them in-phase stock.
iI am not surprised here, in my experience JJ tubes suck sound very flat and lifeless when they work at all no charge you are a great guy!! someone else would have sold him the RCA tube for at least $100 right now!!
Dude, go to a TV repair shop and pay 15 bucks for any 12ax7 they have in stock. I have every brand of "cool" and paid the same as new production. People overcharging for "mojo" are terrible.
Changing a tube while the amp is on? 😱
Hello Sir, I e-mailed you about my AC 30 Looking for price and turnaround time. I know your busy but please let me know if you accepting work. Thanks for sharing your hard earned knowledge.
I've always heard the TBX AC30's were not built as good as the later AC30's that came after. I'm guessing they are referring to the layout and design etc. But I have played many TBX AC30's and they always sound better than the later redeisgned AC30's to my ears. Some better than others but better than the AC30's tone wise that came after the TBX models. I'm not sure why. Maybe you know something about this? Maybe because the TBX had Made in England Alnico blues and the the AC30's that came after the TBX had the Chinese made Alnico Blues?
There hasn't been an AC30 since '69 that has it right out of the box. All of them need tweaks/improvements.
The TBX has built-in ground loops and was over filtered.
The CC preamp is set too clean, the loop has a factory error (easily fixed but still) and it has shiny grill cloth.
The Heritage was a terrible unreliable joke where the PCB solder joints can't hear the weight of the turrets.
The HW is over filtered and the cheap ceramics and iffy solder can make things harsh.
The Custom has a bit too much gain, is over filtered, and there can be arcing due to trace proximity on the output tube board.
All these things are fixable.
I'm not impressed by any of them in stock form. The Custom costs the least to be made into a real AC30.
About two years ago I did a video comparing the TBX, the HW, and the Custom, all after getting my JMI+ mods.
@@PsionicAudio I will go check out that video. Thanks!
It just needed a couple new windshield wipers. Keep it!
I know why that amp is humming.
It doesn’t know the words! 😂
Sorry… That’s an old technician joke. I’ll show myself out. 😃
I suspect the owner just had a bad taste in his mouth after paying for the upgrade. Kinds like having an infidēlis mate that you used to love. Trust must be re-learned!