Time for a new tube!

Fired up the system this morning, and it didn't sound right. Top end was okay, but the bass below +/- 80hz was almost completely gone. I was worried that something happened to my Blu-Ray player, since both channels were affected equally. But to be certain I pulled my big Eico tube tester out of the attic, which properly loads the tube and doesn't just rely on grid emissions. My Citation II checked out fine, but one of the Telefunken Smooth Plate 12ax7s in my Mac preamp died. Transconductance was well down in the red in one of the triode sections, with the other one marginal. Probably had 50,000 hours on it. I replaced it with what, IMO, is the Holy Grail of 12ax7s: a Sylvania J.A.N. 12ax7wa. They're very rare. I've had a pair of them for many years and tried them in all sorts of equipment, and I believe it's the best sounding of all the different brands out there, even the Smooth Plate! For those who have equipment with 12ax7s, seek them out. They have bright green printing on the bottle, with the J.A.N. printing above the tube designation. They were probably built in the late 50s / early 60s.
Worth a try for sure!:rocker:

Now that some time in the circuit has taken place, I'm really pleased with the Sylvania. Deeper soundstage, richer sound overall, and better bass. Top end isn't too much different, but seems a little better controlled and more accurate.
I'd like to find another pair to put in the phono stage!