[pjnad]

It seems to me that the volume from one of my channels is slightly decreased as has the "weight" of the sound in that channel. I've noticed this after a few listening sessions this week. Could this be the result of a tube failing? I am not hearing any "noise" and the resolution is fine from said channel.

I have a Modwright swl 9.0 signature preamp, purchased last March, which is my first foray into tube equipment. So far, I love it! I am using a Mullard as a rectifier tube and a pair of Sylvania gb 5687 in the output which are the tubes that I settled on after some rolling. They were supposedly nos when I picked them up last Apil or May. I would estimate that I've put maybe 1500-2000 hours on them.

I know that swapping the tubes from channel to channel would be a way to test, but that's a bit of a hassle, so...
any input would be appreciated.
 Thanks,
Paul

[Scottdazzle]

You need to switch the tubes from channel to channel as the first step.

[dminches]

It would also be helpful if you could test the tubes.  The test results aren't always revealing of what's going on, but it is another data point.

[pjnad]

Thanks guys...but, am I correct in assuming that what I'mexperiencing could be tube related? and not something more troublesome?

[sebrof]

Thanks guys...but, am I correct in assuming that what I'mexperiencing could be tube related? and not something more troublesome?

Could be tube related, could be something more troublesome. Especially since "supposedly nos" tubes.
Seems that it would be easier to swap tubes than to type again...

[jriggy]

and thats the fun of owning tubed gear, is getting in there and swapping! You can leave the cover off while you check this issue. Just dont touch anything in there while it is plugged in.

[pjnad]

Okay, had a chance to swap the tubes from left to right and yes, seems as if the problem was with the tube. Best possible scenario... which got even better after a call to Brent Jesse, whom I bought the tubes from last April. I was planning to purchase a new pair...after some discussion ( and no prompting by me) , Brent offered to replace the faulty tube at no charge if he had one available (which he did). He was very curious as to what the issue is and asked me to send him the tube so that he could test it.
So, a wholehearted recommendation to a very knowledgeable and reputable seller, here's the link to his site:
http://www.audiotubes.com/audtube.htm
I'm currently using a pair of Tung sols that I had but might still be on the lookout for a "better/different" sounding pair if anyone has anything.
Thanks again to all who replied.