isolating a tube problem - ARC LS5 preamp


I have an Audio Research LS 5 preamp that has been making sputtering windy noises (mostly left channel - the sound pulsates in and out) quite noticable a few times when no input program is playing

Being fairly new to tube gear my impression is that this appears to be a tube going bad.I've had the preamp about a year and bought it used. The preamp runs with 10 6922 tubes (I have solteks currently but am looking to upgrade). Any suggestions on isolating the tube which is going bad would be greatly appreciated.

thanks

Tom
audiotomb

Showing 1 response by mrwigglewm

I cast my vote for tube rolling. When I replaced the Sovtecs in my ARC preamp, I was amazed at the improvement in imaging, subtle inner detail, transparency and dynamics. What to replace the Sovtecs with? After experimenting with several different types of 6DJ8s, I found that my unit sounded best with a combination of Siemens 7308/E188CC w/gold pins and either the Amperex 6922 PQ w/gold pins or the rare German-made Amperex 6DJ8 Orange globe logo w/steel pins. I found the Dutch Orange globes to be a bit too analytical in my preamp, but sound great in my ARC amp. The Amperex Bugle Boys and A-Frames are perhaps 90% as musical and detailed as their premium brothers at about half the price. Ditto for the Siemens 6922/ECC88 w/gold pins.
It's easy to understand why ARC had to go with a reliable, easily-replacable tube. However, you can do much better.