These JJ 6L6GC power tubes were OEM in my Ampeg Heritage B-15, (#18). Originally matched and biased by George Metropolus, at Metro Amps, builder of the first 50 Heritage B-15's.
These tubes have one hour on them. Plus, whatever time George would have burned them in at, prior to placing them in the amp. I originally kept them as spares, but have an three different NOS sets these days, including 7581A's.
I will call them 'matched' because, George himself placed them in the amp and biased them, and secondly, I checked them with my Compu-Bias before rolling other tubes into the amp.
My notes show both tubes were precisely and concurrently showing exactly the same readout at plate voltage:
470V - Ik- 43mA - 20.2W
The tubes have no boxes but will packaged carefully.
No trades, $30.00 for the pair shipped
USPS CONUS. Paypal works. They are located in the Nashville area.