6550 replacements for upgraded CD7

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.

Correct Gary. Bottom line point. I would not drop in a 6550 tube in the upgraded CD-7 unless checking with the factory. It may simply be the wrong tube.

@hansk46 

Glad to read that you had good results in switching the 5881 for a Tungsol 6550.  That said, I am surprised you did not damage the CD7.  

Did you check with ARC as to whether the 6550 is an appropriate tube roll for the 5881?  FWIW, I used to own the CD7 and since moved up to the CD8, which uses a 6550 in its power supply. It never occurred to me that the 5881 was interchangeable with the 6550.

Just askin' …...