tube amp help


I recently purchased my first tube amp- a used Audio Research VS 110 with new matched SED winged C 6550Cs put in by the seller. They were biased at 55mV per his recommendations. I've been listening for 1 week- it sounded great until today. When listening there was a brief pop sound and a quick spark from tube 7. I turned it off, waited a couple hours...turned it back on, they all glowed orange, I checked the bias. tube 7 had 0 mV, all others 53-55. Is the tube blown? Do I need just need to reset the bias? If I need to replace the tube do I need to replace a pair?? Any help would be appreciated - I am a tube amp newbie.
jjb67

Showing 3 responses by jjb67

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 checked the resistor with a multimeter- fortunately it's OK- just waiting on a pair of tubes. Thanks for the Arizona Hi-Fi tip!
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.