Topic: Bad tubes?

[Tim]

Very faint volume coming from the left speaker.... I switched the cables at the amp and the right speakers was now faint. switched out the speaker cables with a new set and the speakers was still faint. switched el34 tubes back to the chinese stock's.... same thing.

since there is faint sound coming from the speaker I'm guessing that the channel itself isn't blown and that it may be just a driver tube problem. I'm still new to this tube game so I was wondering what some of you tube veterans thought?

I'm getting some new rca cleartop 12au7's next week but I'm having Jonny over for a listening session tomorrow...

I may see if I can go find a cheap set locally...

[cheshirecat]

Frist swap the tubes systematically (frist outputs, then switch back, then input tubes, and so on)from the right channel to the left channel (don't swap in new tubes until you have located the problem) if the problem follows the tubes, you have a bad tube.  If not, you have problems elsewhere, check coupling caps first, or bring the amp in to have it serviced.

[Tim]

damn, store was closed... thanks for the help cheshire, I'm going to try and narrow it down to a specific driver tube...

it's either the 12au7's or it's a channel in my amp... please god let it be a tube

[cheshirecat]

NP, if you're getting any sound at all its probably a good sign, either a bad/loose tube, loose connection, or bad capacitor.... if it were blowing the fuse that would be bad.

[Tim]

well I pulled the 12au7's and switched both the lefts to the right and vice versa... now everything sounds a-okay, perhaps just a loose tube?

We shall see

I've been in such a rush I've forgotten to mention the other symptoms. Starting last week sometime I would occasionally get a quiet whistling noise coming from that left speaker.. not all the time and not very loud but it was there. I've also noticed sometimes that the spundstage is heavily weighted towards the right speaker. There's been something screwy with the left channel or the left tubes for a week and a half or so... tonight was obviously the worst but it's been awhile coming....

I was going to write up a comparison between the HD Cables and my old Synergistic Research cables tonight too.... oh well, I'll have to put that off for a few days

[ducati]

I would switch the left and right tubes around and see if the soundstage-tilt and whistling follows.

The whistling, or rustling sound (especially when warming) can indeed the the sound of a tube going down.  How many hours on those tubes?

[Tim]

not many, the amp is only 2 months old....

[ducati]

If everything sounds a-ok now (incuding the soundstage tile) I'd switch the tubes L to R (opposite of the positions you had them in last week) and let it settle.  Then wait and see if it comes up again--if it's a tube it will come up in the opposite channel.