Ok back to being a amp problem

Discussion in 'Amps and Cabs [BG]' started by BlacknWhite, Jun 18, 2019.

  1. My Amp (Traynor YBA200-2) seems to be lacking a bit of power as of late. There has been no change in the quality of the sound just seems to be lacking some volume. I checked the bias of the power tubes and they are right in spec from when I checked them out a couple months ago. They are only 1 year old and show no signs of damage. I pulled my V1 and V2 pre amp tubes and tried others I had laying around and no change. The V3/splitter is a 12AU7 and I do not currently have one or a store nearby to grab one. Closest I have is a 12AY7. Could I use this for testing? or would it even work properly to be relevant. Any other suggestions or feedback welcome.
     
  2. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    Something super easy you could try is patching a guitar cord in-between your Pre-Amp Out & Amp-In jacks.

    If this instantly corrects the problem, you could simply leave a short cord in place permanently; or clean the dirty/tarnished shunt in your Amp-In jack that was causing the poor connection between your preamp and poweramp sections.
     
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  3. Well after mass amounts of trouble shooting I found the issue is the cab. It's a Traynor TC410 neo. It doesn't seem to be able to handle much power anymore. I tried two amps through it now, a couple bass's, swapped out the speaker cable, put all EA's flat and even cut bass. As soon as I get past 12 o'clock on either amp it starts distorting. All the speakers seem good. The horn is off. Tightened all the hardware and all four speakers. All the wiring is tight.... I'm at a loss. This thing use to pound.
     
  4. Wasnex

    Wasnex

    Dec 25, 2011
    One or more of the speakers may be blown. I don't know how the cab is wired, but if if it uses series parallel, when one driver goes open, two drivers stop working. So your 410 may be functioning as a 210.

    If the drivers share a chamber, when one of the drivers stops working it moves (to a large degree) out of phase with the active drivers. This can reduce the low end and volume.

    You could test the cab with a 9V battery. If the drivers are properly connected and all working, they will all move in the same direction when you connect the batter to the speaker terminal. If one of the drivers moves in the wrong direction, you have some troubleshooting to do.
     
    Last edited: Jun 22, 2019
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  5. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    Seems more like you are asking the amp to do more than it can. Most amps stop making clean power well before max rotation of the volume pot. Usually between 12 and 1 o'clock. It may seem to get louder but all you are getting is distortion. So if you are past halfway on the vol you will get distortion and not blown speaker unless you pushed it into clipping then you may have fed your speaker DC and killed it . But with tube amps I am not sure about that last part. The good part is you probably did not blow a speaker . also just because power tubes will Bias does not mean they are still up to snuff and putting out what they should. If your power has faded slowly over time and you have been pushing the amp past 12-1 O'clock the tubes may not be all that good. The harder you push tubes they faster they go bad.
     
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  6. I pretty much found on the tube amp I'm using that 1 o'clock is the sweet spot. That's where all the power seems to kick in and it turns alive. I'd hope that running a 200 watt tube amp at 1 o'clock wouldn't classify as "pushing it too hard". The current tubes that are in there were replaced just over a year ago. The other SS head I was using is only 120 watts and it was doing the same around 1 o'clock. I've had it through this cab before with no issues so I have to think it's the cab. I'll have to rip it apart when I have some more time.
     
  7. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    In all actuality the volume knob position makes little difference past a point except it introduces distortion. AT somewhere between 12 and 1 your amp is out of clean power it does not matter how much power your amp puts out RMS or peak . Just because the knob keeps turning does not mean it is doing anything good. And I am not trying to be a Wise A** just trying to get a point across. Tube amps distort very musically sounding to a point and it would seem you have found it at 1 O'clock setting. and yes pushing an amp into distortion is in fact pushing it.Also 200 watts is not really all that loud. It can get approx. twice as loud as a 20 watt amp through the same speaker cab
     
  8. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    The difference in loudness between a 120 watt amp and a 200 watt amp is barely audible. So both amps acting the same would be right. My guess is you will not find any Issues with your cab. Also no two potentiometers (volume control)'s are the same so knob position is irrelevant. Again not trying to come off as a know it all just trying to help . I have been where you are amp wise and thought similar but experience is a good teacher.
     
  9. Oh I get where your going and Agree that 200 watts is not super loud. That's why I usual have it at about 1 o'clock lol. But this distortion is NOT very musical it sounds gawd awful. Before It literally had no distortion. You could tell there was a smidge of OD but sounded pretty clear and punchy. Now it sounds like crap through both heads.
     
  10. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    And I missed the second head part my bad. Strange that the speaker would suddenly start eating more power unless something went goofy in the crossover.
     
  11. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    I think you'll find that despite popular myth this is not a thing that can happen.
    An amp simply will not deliver DC to the speaker unless some extraordinary things have happened to it. The stories about square waves and underpowering are a grain of truth buried in layers of myth.

    Firstly an amplifiers nominal power is normally measured at 1% distortion. If you drive it to very heavy levels of distortion it may produce significantly more than the rated power, maybe even enough to cook the speakers, whose rated power is usually based on what will overheat them internally.

    Secondly a heavily distorted signal contains a lot more high frequencies than a clean one. Tweeters are normally rated at lower power than their matching woofers, so a very distorted signal may cook the tweeter at a power level the woofer can survive.

    This is all why it's usually recommended that if you use a lot of distortion your speaker rated power should exceed the amp rated power, maybe even double.
     
    Last edited: Jun 22, 2019
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  12. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Back to the OP. It would seem something has changed about your cab. Go with what Wasnex is suggesting.
     
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  13. Wasnex

    Wasnex

    Dec 25, 2011

    Although a long shot, it could be a faulty speaker cord. Awhile back I noticed one of my tubes amps was making a nasty distortion when I pushed it hard. I figured it was just the tubes getting old. Then last week one of my GK 2000RBs started acting like something was going bad. I have two of these amps stacked on top of each other and the bottom one worked fine, but the top one was having trouble.

    I had recently swapped a used preamp board into the top amp, so I assumed that was the problem. However during troubleshooting, it became clear the problems was after the preamp. I cranked up the Master pretty high and there was a small pop and then the sound cleared up. This amp has two output sections so I switched to the other side and it seemed to be working fine now as well, where it had been intermittent before. Since both outputs had previously been having intermittent problems and now they both sounded good, this made me suspect the speaker cable.

    I unscrewed the ends on the speakON cable and all of the fasteners that hold the wires in place were loose. I had to strip a bit of insulation off a couple of the wires to get them deep enough into the sockets so they could be secured. Now the speakers sound better and I haven't noticed any intermittent problems for several days. My fingers are still crossed though :nailbiting:.
     
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  14. ezstep

    ezstep

    Nov 25, 2004
    north Louisiana
    I hope the cure was that simple. But....
    Last weekend, I connected the subs, bumped them up a bit and the sound was great. Walked to the other side... and no sub sound. It turned out to be a (usually) reliable speakon cable in which one of the wires had simply worked itself loose. Re-tightened it, and huge sound again.

    Sometimes the answers are very simple. I hope your problem is cured.
     
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  15. Ok after another afternoon of troubleshooting the cab is fine. Pulled the whole thing apart verified all the conections and crossover were good. All the speakers are moving together and move freely. The 120 watt Ampeg head sounds good but breaks up when I push it (its 50 years old). My Traynor YBA200-2 was still doing the same but when it breaks up it sounds horrible and the volume drop got worse. I opened it back up and the bias on 2 of the power tubes were 20mv over spec and the other 2 were reading almost nothing. I'm hoping it's just a power tube. I moved the two tubes that were reading to the two slots that weren't and they read fine and the two that were not reading were still not reading in the 2 slots I moved them too. I won't be able to get it in to the shop for a while because it's a 3 hour round trip. Looking for the tube guru's. Does this sound like just a power tube issue? It just happened all of a sudden it wasn't dropped or being played at jam volume when it happened.

    @agedhorse
     
  16. Wasnex

    Wasnex

    Dec 25, 2011
    Did you try to adjust the bias? The owners manual says the tubes should be set for 80mV at the test points. The Service Manual says 75mV +/-10mV. This equates to 40mA of current per tube. Each tube has a 2 ohm cathode resistor, and the voltage is measured across the cathode resistor at the test points.

    The tubes are ordered from left to right 7,4,5,6, (this is with the amp right side up). Per the Service Manual, tubes 6 and 7 are grouped together on one side of the output transformer and 4 and 5 are grouped together on the other side. This is a very confusing way to order the tubes IMHO.

    You could max the bias out for minimum current. This will produce the minimum voltage reading at the TP. Next carefully pick out the two tubes that pull the proper amount of current and install them so one is on each side of the output transformer. Can you adjust for 80mV at the TP? Reset the bias for minimum current and turn the amp off to let the tubes cool. Next move the tubes to the other two tube sockets and repeat. If the tubes work properly in all four sockets that amp is probably good to go.

    Make sure you have a speaker hooked up to the amp. Also, when you are running half the tubes, the output impedance is doubled. In other words, the 4 ohm output becomes 8 ohms, and the 8 ohm output becomes 16 ohms.

    The link to the Service Manual: http://traynoramps.com/downloads/servman/sm_yba200-2.pdf

    If the other two tubes are pulling any current. You can test them as well if you like. If it is not possible to bias the cold tubes to the proper range, they are probably toast and have used up their emissions. If they can be biased to the proper range read the following:

    What I have seen several times with mismatched tubes: When a hot and cold tube are on the same side of the output transformer it's fairly common for the hot tube to get hotter and the cold tube to get colder. It doesn't always happen this way, but it is fairly common. The degree to which this happens varies quite a bit between different pairs of tubes. Due to this, you may try shuffling the tubes to see if you can get the existing tubes to work in a different order...sometimes you get lucky. Each time before you shuffle the tubes, reset the bias for a minimum reading at the TP.
     
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  17. Thanks or the response! I have the service manual and the tubes that were reading I was able to get them right around 80mV. The other two were only reading like 3mV. The ones that were reading good results worked in all the sockets. The two that were reading correctly were the ones originally in 5 and 7 and the duds were 4 and 6. The 2 dud readings never changed even after I adjusted the bias pot.
     
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  18. Wasnex

    Wasnex

    Dec 25, 2011

    Sounds like you just need a new matched set of tubes (IMHO).
     
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  19. Yeah I've ordered a set. Figured I'll get them in 3 or 4 days and I'll swap the pair that are not reading. Hopefully that does the trick and if not off to the shop when I get a chance.
     
  20. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    Just pull some tubes from GC floor models.




    Just kidding, don't do that
     
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