05-13-2017, 05:25 PM
Sometimes the flourescence will "dance" to the music in an audio amp. As stated, if it's probably gassy, even NOS tubes can get this way. I've heard about running 'em for a while can sometimes clear up some gas to the degree possiible with the internal getter. I can recall an ancient Eico that did this. The 6L6's lasted for years!