Call Calvin at ARC. I am a little puzzled by your Q. I used to own the CD-7 with upgraded power supply. The upgrade involved replacing two of the three 6H30 PS tubes with one 5881 tube. I am puzzled because I'm simply not aware that one can drop-in a 6550 or KT-88 tube in exchange for the factory installed 5881 tube. Be careful.
9 responses Add your response