Tubes Became Microphonic


About 6 weeks ago I put in some NOS Sylvania 6SN7's into my Rogue Magnum 99 preamp. Just today they became microphonic. Just touching the volume knob caused a metallic sound through the speakers. Tapping anywhere on the chassis did the same. Is this common? Anyone else with similar experience? Is it just a tube issue or something else? I do plan on speaking with Rogue asap but wanted advice/experiences here. thx
ehaller

Showing 2 responses by ehaller

Thanks, Mark at Rogue thinks the same. I'm putting back in the stock EH's and sending the NOS back for testing. The NOS was screened, a matched quad purchased from Rogue. You gotta love their customer service. Mark actually answered the phone when I called first thing today. I might try the new EH's, cheap enough.
Update- I put in the stock EH tubes and the preamp works perfectly, no noise. Mark at Rogue has since checked out the NOS I sent back and he finds nothing wrong with the tubes. No noise, no microphonics. Is it possible for a tube(s) to be microphonic and then not be? I also had put in a new CDP into the system and new power cord to the CDP earlier in the day before the tubes became microphonic. Could this have caused a tube issue, maybe some sort of electrical interference? I'm baffled by this and wonder if anyone else has had a tube issue similar. Rogue is sending a new set of NOS and I should have early next week, hope no issues.thanks for the help.