@aolmrd1241 Thx for posting that pertinent info. Good to know. Last night, I turned off the lighting in the listening room - and the one tube is WAY brighter than the other. But, there is no distortion, noise or arc'ing - or any issues. Actually, the music sounds kind of great. All is good.
Mullard M8136
Last year, I purchased a ‘matched’ pair of NOS M8136’s with the Mullard logo. They’ve been sitting un-tested in a drawer. Three days ago, I put them in my preamp. They sound very nice. The glow at the bottom of one tube is much brighter than the glow on bottom of the other. There is no tube noise or arc’ing at all. The vocals are dead-centered. I switched tube positions in the preamp - and the vocals remain centered. After playing several tracks, it’s difficult to tell if there are any differences between the channels. There could possibly be a tad more volume coming from the channel that has the tube with the brighter glow. If so, it’s not much. Certainly not enough for the balance to be lopsided. Perhaps, this bright glow is normal for the M8136 – and maybe the other one is actually dimmer than it should be. I don’t know. Yet, this glow is brighter than all my other 12au7 tubes. Unable to return them since I waited so long. Any opinions if this tube should be removed before any problems arise. Though, they do sound quite nice.