Low volume from tube amp

Discussion in 'Amp Tech Center' started by bossfrog, Aug 22, 2019.

  1. bossfrog

    bossfrog TDPRI Member

    Posts:
    31
    Joined:
    Jul 31, 2015
    Location:
    Green Bay, WI
    OK so I bought a Traynor YCV80 amp on the cheap because my neighbor was having trouble with it and didn't want to pay an amp tech to fix it. Being someone who isn't afraid to tackle these kinds of things, I offered him $125 and surprisingly he took it. Let me describe the issue first.

    Basically, an 80 watt tube amp should blow your head off if you're sitting 3 feet from it with it cranked. On the clean channel, with the volume all the way up and the master volume also cranked, the volume is nowhere near where it should be. To give an idea, I can strike an open G chord and talk to someone sitting next to me only raising my voice a little bit. You would expect to have to pretty much yell pretty loudly to even have a chance of being heard over a cranked 80 watt tube amp. Also, with the channel volume on 5, and the master volume on 5 you basically have what I would call bedroom volume. The drive channel is only slightly louder and does not distort nearly as much as what this amp is capable. Looking at the power tubes, two of them are glowing at a normal brightness while playing but the other two are barely glowing very dimly and do not get brighter during active playing. So basically, I'm only getting the "push" in a "push/pull" design here. All switches and knobs work correctly. It's purely a volume issue.

    So here is what I'm currently thinking, and my amp knowledge is very limited which is why I'm posting this. I feel like the phase inverter may be the culprit with one of the two triodes being dead. That would explain why two of the power tubes behave normally and two of them only have a dim glow that doesn't change. I don't have the amp yet. He's keeping it a few days until he buys a different amp. If I swap the power tubes and the dim ones then work normally, that would rule out the power tubes being bad in my mind.

    Okay, now it's time to educate me, please. First, does any of what I just said in the previous paragraph make any sense? Second, if it does and replacing the phase inverter does not fix the issue, what else should I be looking at? Oh, and the speakers are hooked up correctly, they are in phase with each other, not out of phase. I did read something about dirty effect loop connectors causing issues, but this doesn't sound like that. I've had that issue before with a 6505+ I used to have. Thanks for any responses I might get on this!
     
  2. dogmeat

    dogmeat Tele-Afflicted

    Age:
    68
    Posts:
    1,027
    Joined:
    Oct 12, 2017
    Location:
    Alaska
    I'd start by checking all the tubes. Traynor has all their manuals on line too...

    http://traynoramps.com/support/manuals_spec_sheets

    I've had 3, still have one. I like them. I had issues with one and called the tech service. the tech sent me the right diagrams & other info that helped me solve the problem.
     
  3. Faceman

    Faceman TDPRI Member

    Posts:
    95
    Joined:
    Aug 15, 2018
    Location:
    Ohio
    I would almost bet it’s the PI. I’ve seen that so many times I can’t count. Outside of that, you’d want to take it to a tech that can test it properly. If the PI doesn’t fix it, it’s likely to be a resistor that has failed in my experience.
     
  4. bossfrog

    bossfrog TDPRI Member

    Posts:
    31
    Joined:
    Jul 31, 2015
    Location:
    Green Bay, WI
    Wow thanks for the quick replies. Dogmeat... did not know they had the manuals (I assume you mean service manuals?) online. I'll look for those. Faceman, so you have seen this same issue that I described here? I now feel a little more hopeful that the PI might be the fix. I have at Sovtek 12AT7 that I will probably try for PI. Can V1 and/or V2 cause these same symptoms?
     
  5. LightningPhil

    LightningPhil TDPRI Member

    Posts:
    27
    Joined:
    Dec 1, 2018
    Location:
    Nottingham, UK
    Had a similar issue with a Fender amp. Half of the phase splitter was dead. Now it's fixed it's too loud again so I've fitted an attenuator.
     
    Chicago Matt likes this.
  6. tubedude

    tubedude TDPRI Member

    Posts:
    11
    Joined:
    Jul 26, 2013
    Location:
    east georgia
    The output transformer may have lost half the secondary winding. Do you have a volt meter to check the plate voltage on the output tubes on pin 3?
     
  7. bossfrog

    bossfrog TDPRI Member

    Posts:
    31
    Joined:
    Jul 31, 2015
    Location:
    Green Bay, WI
    I have a cheap multimeter that should do the job. What values am I looking for?

    I did find that Traynor sells the output tranny for this amp for $70 if that ends up being the problem. The tech guy at Traynor yesterday said the ones they use in this amp are pretty sturdy and he's never had to replace one that he can remember.

    But again, with the power tubes being before the tranny, I don't think that would explain why two of the tubes appear to be under powered, would it?
     
  8. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Posts:
    3,242
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    Step 1 of amp troubleshooting is always a voltage chart.
     
  9. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    67
    Posts:
    9,309
    Joined:
    Mar 2, 2003
    Location:
    Lawndale CA
    How old is the amp? That model has been made for quite while.

    If it's 15 years old, older, or getting close the filter and bias caps need to be replaced. They have a service life of 15-20 years and most owners don't know that. If it's that old and the work's never been done (or there's no documentation of it) that's priority one. They can blow without warning and there's no visual or electronic check to be sure they're OK.

    But you mention having limited knowledge. Do you understand all the safety rules involved with opening up an amp chassis? If not - just take it to a tech. And as far as filter caps go, you often have to TELL them to replace the things - many techs only do what's requested, not what's needed.

    That may not solve your problem,. but if it's an old amp it has to be done BEFORE you can solve your problem, as your voltages can be out of whack and/or you could have power transformer problems.

    If it's a newer amp you can try replacing the PI tube - but which tubes look "bad"? If they are next to each other it has nothing to do with the PI - the power tubes are grouped as inner and outer pairs. So if the issue is adjacent pairs - take it to a tech. There may be a loose filament wire. As I recall this amp runs on a DC filament supply for reduced noise. Not complicated but if you don't know that you can get confused by "wrong" filament voltages right away.

    If you're gong to work on amps get rid of your cheap multimeter and get a decent one. I've seen $5-25 multimeters that didn't read voltages or resistance within 25% of accurate. And if you are going to work on amps you really need an LCR meter to test capacitors - even a good multimeter will only let you do partial work.
     
  10. bftfender

    bftfender Friend of Leo's

    Posts:
    4,134
    Joined:
    Dec 21, 2017
    Location:
    York PA
    had a real puzzle one year. mesa 5:25 Express...only had minimal volume. Went over tubes..pulled chassis out of amp..didn't see anything wrong. When i hooked the speaker back up. I plugged into other jack..bam..there it was..the jack & input had become a corroded mess. i was pleasantly happy.
     
  11. bossfrog

    bossfrog TDPRI Member

    Posts:
    31
    Joined:
    Jul 31, 2015
    Location:
    Green Bay, WI
    Yes, and I know how to discharge them and test that they are discharged. Where my knowledge is limited is in the theory of the circuitry and advanced troubleshooting. I've replaced components on a lot of amps, tube and SS.
     
    Silverface likes this.
  12. bossfrog

    bossfrog TDPRI Member

    Posts:
    31
    Joined:
    Jul 31, 2015
    Location:
    Green Bay, WI
    FOLLOWUP: I always hate when people don't report back with results when you try to help them, so here we go.

    It took me about 5 minutes to find the problem with the lack of volume. In fact, there was NO problem at all. Someone had replaced ALL THREE 12AX7s with 12AU7s. Popped my 12AT7 into V3 and a couple of 12AX7EH in V1 and V2 and it now appropriately decapitates those sitting too close.

    Best $125 I ever spent :D
     
    Last edited: Aug 24, 2019
    Silverface, D'tar, JL_LI and 3 others like this.
  13. ArcticWhite

    ArcticWhite Tele-Holic

    Posts:
    500
    Joined:
    Apr 14, 2009
    Location:
    Portland Oregon
    Hahahahaha!
    That's pretty funny.
    Glad you figured it out before you started in with the soldering iron.
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.