2. amps-preamps
  3. 983821701

Tube amp blues

I'm sure that there is a simple explanation but being new to tubes I just haven 't learned it yet. When I turn on the amp it starts with no problem and plays wonderfully. After about 3 - 5 minutes it starts making a "static-y" sound from the right channel. This is not constant, it comes and goes about every 10 to 30 seconds and there sometimes is white noise between the louder static-y sounds. Both sounds (Static and white noise) come at different levels sometimes louder than others. Sometimes there is no "static-y" sound at all and all is quiet, just great sounding music. I have done some checking and this sound does not respond to any of the other equiptment. Only the amp needs to be on for it to happen. When the whole system is on there is no difference in the noise. I have played music from my CD and Turntable at different volumes and the noise is not affected. I have found nothing that can be done to stop the sound or make it worse except turn off the amp. It only starts after the amp is warmed up. Could this be a bad tube? Or a bad component on the board that is causing this after the amp warms up? Any Idea's.

Thanks Rick
richardzerambo
gthirteen
349 posts
 
All I can suggest is to swap the tubes between channels, to see if it goes away. It could certainly be a bad or microphonic or old tube, but could possibly be something more. I'm sure someone with more knowledge than I will respond shortly, but this may get you started... Good Luck!
Joe
jcbtubes
400 posts
 
Richard- Since you didn't detail that the noise was specific to one channel, I'll assume that it is occuring in both channels. With that said, swapping tubes from one channel to the other may not provide any further insight into the problem. However, swapping or just reseating the tubes will tend to "clean" the tube pins and socket contacts which is highly advisable. Not knowing the particular amp, I can't offer much more than the tubes may need replacement. I would start with the small signal tubes first, before replacing the output tubes simply because of the cost associated with them. FYI- New Old Stock (NOS) tubes are usually preferred sonically, but can greatly increase the cost of retubing. Output tubes are best acquired in matched sets to help insure longer life, maximum power output, and hopefully equal aging characteristics. You might also consider having a few spare small signal tubes on hand that are known good, to help in the troubleshooting efforts. Goodluck.
najo
18 posts
 
You must swap tubes with some different ones! Start with the driver stage tubes (the small ones) . Then sub out the power tubes. Most problems will most likely be tubes. Sounds like the tube gets noisey(common) when warmed up.If you do not have extra tubes now is the time to get them. You will use them anyway if it is something else. Only after absolutely ruling out tubes is it time to look elsewere.
pops
2,272 posts
 
Sometimes swapping tubes (same tubes different channel) in a preamp solves that problem, it has to do with gain, not sure about power amps but worth a try. Good luck.
richardzerambo OP
15 posts
 
Hi everyone and thanks for the ideas so far. The unit is a Golden Tube Audio SE-40 and the noise is only in the right channel. I have been spending a lot of time trying to figure out what this noise can be so I have a lot of information about the noise. The best way to describe it is that it sounds like when you have a dirty volume control and every time you adjust it you get a loud crackling sound. I have timed the noise and it takes anywhere from 9 to 12 minutes for it to start from the time the amp is turned on. It continues until the amp is turned off. I have kept it on for 25 minutes to see if it would stop but it didn't. This noise happens without any input to the amplifier. The volume control on my preamp has no effect on the noise, the noise remains constant even at high volume. Once the noise has begun it happens intermittently with no set pattern but, there are no breaks in the noise except for the ten seconds or so between noises. From the responses so far looks like I had better get some new tubes.
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