Traynor YBA 300 Starts out quiet and when it warms up loud 60HZ humm

Nighttrain1127 · February 17, 2016, 09:44:13 AM

I have a Used Traynor Yba-300 It had some initial noise Issues when I got it . I changed out the pre tubes and it went away, For a while. After about a month it started making the noise again after it warms up about 20 minutes or so. Got brand new JJ pre tubes and it was quiet again for a few weeks but now it is back after it warms up. Any Ideas and it is only with the gain turned up. If I keep the gain down low it is quiet.

Thanks in advance

Aussie Mark · February 17, 2016, 02:46:18 PM

After it warms up are the bias LEDs still all in range?

Thornton Davis · February 17, 2016, 02:48:02 PM

What Mark said, but if you need help, contact Traynor through their website and they'll help you out.

TD

Nighttrain1127 · February 17, 2016, 03:49:08 PM

The Bias lights were all off. However after the suggestion of Bias I set them all a hair cold and then re Biased until the lights just went completely out . No Hum So I guess it is not a perfect system will have to see if it starts doing it again if resetting the bias works. Thanks for the suggestions. And if it does it again I will contact Traynor.

Nighttrain1127 · March 17, 2016, 04:06:31 PM

Just a correction to my first post if I keep the Master down not the Gain then it is quiet. But when I turn the master above 2/3 it gets noisy. Not killer noisy . I did some troubleshooting with Traynor removed all the tubes put in one set at a time and no matter what Pair I put in for the 4th pair it gets noisy again so I bought a matched Quad and once the fourth pair of tubes was put in it got noisy again. So I am now wondering if the first tube pair or the second pair is creating some noise but not enough to hear it until the 3rd and 4th pair are in? I have rebiased and right after I set the Bias it gets quieter then after it really warms up 30 to 45 min the noise is back. Any new Ideas

Psycho Bass Guy · March 17, 2016, 09:44:45 PM

Your output tubes are severely unbalanced and what you're hearing is a bias mismatch.

Nighttrain1127 · March 21, 2016, 03:02:44 PM

So I Need to replace all the power Tubes then Is what you are saying.

Nighttrain1127 · March 21, 2016, 03:04:00 PM

Thanks for the Info PBG

Dave W · March 21, 2016, 04:56:45 PM

Quote from: Nighttrain1127 on March 21, 2016, 03:02:44 PM
So I Need to replace all the power Tubes then Is what you are saying.

No, not unless one or more has gone bad. You need to have their bias adjusted and matched.

Psycho Bass Guy · March 21, 2016, 09:59:26 PM

Quote from: Dave W on March 21, 2016, 04:56:45 PM
No, not unless one or more has gone bad. You need to have their bias adjusted and matched.

Yes, and further to that, I strongly doubt that it is a tube fault at all. It's far more likely that some part of the bias circuit has failed. Traynor has had serious problems with stage regulation because of part failure in all their modern tube bass amps to varying degrees. I suspect that the amount of electrical heat being generated is above the thermal limits of the bias circuitry, either a connector, resistor, board joint, or any combination of the above. The potentially bad news is that if the amp ran this way for long, it may have toasted half of its output tubes already, and if you just buy new ones and stick them in there, the new ones will overdissipate too.

Nighttrain1127 · March 22, 2016, 05:13:54 AM

So it is tech time then?

Psycho Bass Guy · March 22, 2016, 09:38:30 AM

Yes. Odds are that the "gain" is actually tied to the master volume and it may be something as simple as a faulty ground in the preamp, but loud hum out of nowhere usually means 'output stage.'