Sylvania 5751 / 12AX7 / ECC83 brand new triple-mica black plate perfectly matched 1957 pair from the same batch in their original Swedish military aluminum tube canisters with folded-wire getters and polished steel pins. Fifty-five years old and just recently released from military surplus, so they are brand new with 10,000+ hours of life left on them. The aluminum canisters have February 1974 on the label showing the last time they were tested and marked by the military to assure they were in perfect condition and ready for battle. You just don't see these on Audiogon and I have several matched pairs and quads available.
These are the famous and extremely sought after Joe's Tube Lore Sylvania 5751 tubes. Joe found these and their identical commercial version brothers the Gold Brand steel pins to be the best of the best of all 12AX7 and 5751 tubes. I've attached the link to Joe's very comprehensive review.
The 5751 is a drop in replacement for the 12AX7/ECC83 tube, the only difference is a slight drop in gain that will require you turn up the volume nob a click or two to compensate. The upside is the 5751 has a much quieter noise floor that has the benefit of exposing more hidden resolution, no tube rush and images just leap out from a black background. In addition, these tubes were designed for the US military and commercial aircraft so they are super rugged, have no microphonics, and will last a very long time.
Brand new for the 5751 / 12AX7 / ECC83 on my calibrated Hickok 600A is 1,250 / 1,250, this pair tested:
Tube 1: 1,450 / 1,450
Tube 2: 1,450 / 1,450
Price for the pair is $219 plus $7.50 for USPS Priority Mail shipping with $230 insurance. International shipping is to be determined by the final destination.