Static noise from speakers

Yes, I do have tubes. I am using a Conrad Johnson CJ60SE amp and a VTL 2.5 preamp. The tubes in my amp are getting kind of old (2 year old, and a fair amount of listening time). I now seem to vaguely remember that a few months back I had a similar problem but to a lesser extent and after cleaning tube pins and sockets with alcohol the problem went away for some time. Based on your comments Reubent, you probably nailed the problem first shot. The odd thing is that the system sounds great to my ears...except for this intermittent static noise. I thought that when tubes were on their way out the system would not sound so good. My lack of experience with tubes I guess. Problem is usually in Left channel. I will follow your recommendations and swap tubes sides to see if I can isolate problem to one side.

Do you believe that only one tube is causing this or the tubes on the one side? Is there anything visual that I could inspect to determine if I have a bad tube? I do not have a tube tester.

Thanks,
NJT

NJT,

There is not likely going to be any visual indication of the problem. However there are some logical steps you can take to isolate the issue to a component, then to a particular tube type and potentially even down to a single tube.

First step would be to isolate the issue to either the pre-amp or amp. To do this, simply cross over the interconnects between the amp and pre-amp. So left pre-amp output to right amp input. If the problem moves from the left channel to the right channel, you know the problem is in the pre-amp. If the problem does not move from the left speaker to the right speaker, you know the issue is in the amp.

Once you determine what component is causing the problem, you can systematically swap tubes betwwen the left channel and right channel. I would start with a single pair of tube, like the output tubes or the input tubes.

I'm not an expert and my tube experience is mostly limited to components that have a relative small number of tubes. Hopefully you will be able to isolate the issue relatively quickly, then decide if you need to re-tube the entire component or just replace a single tube or tube pair.

Enjoy,

TIC

Reubent's advice on isolation of each component is spot-on. If static noise is still prevalent I would suggest swapping your source ie. CD player. I have encountered this intermittent static noise from one channel previously and suspected everything from the tube preamp to the power supply. In the end it turns out that the CD player has some bad capacitors that are causing the hissing/crackling noise. You might want to keep that in mind. The funny thing is the static noise will not happen if I leave my CD player switched on 24 hours a day. Since that day I have never switched off the CD player until today.

Ryder makes a good point and it is something you should determine before chasing after a tube.

If you cross over the interconnects between pre-amp and amp, and the problem moves to the other speaker the issue could be in either the pre-amp or source component. To isolate further, cross over the cables between the source (cd player?) and pre-amp. If the problem moves again, the noise is coming from the source component, not the pre-amp.

Of course, if you have multiple sources and you've heard the problem using different sources, you can skip that step.

Enjoy,

TIC

This morning I swapped interconnects at the preamp and heard some static noise on the right channel. I thought, good so it has to be a preamp tube issue. But, a few second later I also hear static noise on the left channel and then later the noise was more prominent on the left channel. Basically, I think that the problem is the same, I probably had not noticed the static noise in the right channel since it is so faint and only occasionally occurs. I guess this points me to an amp tube problem. The problem occurs with any source hooked-up.

Thanks for all your help and please let me know if you have any more troubleshooting tips to share.