Bought from Brent Jesse Recordings & Supply, Inc. on 12/2/2011. Circa mid 1960's.
These were my backup tubes. I put 40 hours on them to make sure that they were in good shape, as there was a 30 day warranty by the seller.
Then I stored them. They are dead quiet. These are not needed, as they are my third backup pair.
Probably the best 12ax7 out there.
It's what I'm using in my Aesthetix Calypso preamp- (plus a pair of 7308 Amperex white letter PQ-USA- This is the best combination that I have found in that preamp.)
This ad is for a pair of Telefunken ECC83/12ax7 smooth plate.