These are 2 tightly matched sets of tung sol 6550 tubes all the same date codes and same match batch number of 5. Date codes are 3226716-3 (14th week of 1967). First pair are matched 29 and 31.8mA and 4.5 and 4.4 gm respectively. The 2nd pair are 26 and 27mA and both 4.3gm. Realistically these tubes could operate as a quartet and be biased properly. These tubes were tested on my accurate Maxi Matcher 2. There is no damage to these tubes and were tested for function in one of my Ampeg SVT's. Nice chance to get the real thing. They definitely give my SVT's an amazing sound but then again so do the GE 6550's. I have several matched sextets for you SVT guys.
According to my Maxi Matcher 2, nominal readings for these tubes are >20-55 mA and >3.2 for gm. These tubes are strong.