I am offering an unused set of two matched octets, 16 tubes of GE 6550A. I purchased these from Jim McShane many years ago as a backup set for my Cary SLM200 amps. I actually purchased a total of 4 Octets a few weeks apart. When I purchased these (I was local to Jim), Jim told me I didnt need a backup set because at the bias my amps were run at, these tubes would last a long time. He was right. The original set is still in my amps and going strong. These unused octet sets have been sitting all these years. I am planning to sell my amps so I no longer need these tubes.
Note that these tubes are as received when I purchased them from Jim and are unused. This is the only claim I am making for these tubes. I cannot predict how they will react or how long they will last in your application.
I am not sure how to rate tubes so I rated as 9 out of 10.
They will be well packed for shipment to protect them. Tubes will ship after payment clears. I ship Fedex, my cost to domestic buyers.