tube amp help

My guess is that tube 7 is bad. If you live near some place where you can have all the tubes tested, I would do that just to make sure there are no other problematic tubes.

I would also read the part about tube bias in the manual. I have never owned or biased a VS 110. But I have owned a number of Audio Research amps and currently own a Ref 110. Tubes in Audio Research amps are normally biased in pairs. Again I would check the manual but normally the bias is 65mvDC. If all the other tubes are fine I would get a replacement tube that matches the other tube in the pair. If the tubes are biased in pairs which I am guessing they are. You don't need matched quads, just matched pairs. Though it doesn't hurt to get matched quads.

When you bias the tubes the amps needs to be warm with no music playing. 15 or 20 minutes is good. Normally if I am going to check my bias I do it after a listening session. On new tubes it is best to check the bias a few times. As new tubes break in the bias can drift a bit.

Make sure that the Amp is connected to your Speakers when setting the Bias and as stated above give the Tubes a warm-up first.

Thanks for your responses. I appreciate the reference to Antique Electronic Supply in AZ since I live in Scottsdale. The Audio Research manual does say 65 mV DC- but the seller said he was told 55mV from his tube supplier for these particular tubes. I might change it to 65. The tubes are matched pairs- so I guess I'll get a new pair.

In the mean time- I assume I shouldn't use it, but someone told me I could listen at low volumes with a single blown tube.

I run SED winged "C" tubes in my Ref 110. That is the 6550 tube that Audio Research recommends for all their amps. These tubes don't need to be run at that low a bias. And a bias that low will adversely affect the sound quality of the amp. I run the tubes in my Ref 110 at 63mvDC.