I use NOS because most of the current production is not as good as it "used to be". Good tubes are the best place to start, and Vintage Tube Services is a good place to get good value tubes. Your amp calls for 12AT7's, 12AX7's and EL-34's. I don't advocate touching tubes at all while they're in use. I've used several tube dampers, finding Herbies Hal-O's to be about as good as it gets. You're not going to correct a microphonics problem with dampers. Once they becomes noticable ... time to replace tubes. Fortunately the small signals that you use are widely available. Don't try to be too cost conscious here. Try some used Telefunken smooth plates for 30.00 - 40.00 ea and see what you hear... Give Andy a call at VTS ... you can't go wrong. I buy 80% on mine there. Be careful on auction sites ...
Tube Amp "Ringing"
I have a Jolida SJ-502A tube intergrated amp and tonight I noticed a "ringing" sound coming from the amp. Didn't notice it when the music is playing, but when I changed my CDs and was close to the amp, noticed the ringing. Was curious on what it could be and how I can solve this problem. btw, I'm a "tube newbie", and help and suggestions would be appreciated. Thanks.