6550C vs KT88


I am using Audio Research VT100 Mk2. Thinking about trying the Svetlana KT88 to replace my 6550s. What are the biggest differences between the two? will this cause any kind of electrical problem in my VT100??
Thank you,
a4yayac25d
So sorry to hear this. I know quite a few people, myself included, who run them without any problems. In fact a sales manager at ARC told me they had considered putting svetlana kt88's in as oem equipment.

Did you turn down the bias setting for the new tubes? As your old tubes aged, you would have been turning this up. I know the tubes have to be very closesly matched too.

From what I have read, usually these amps are designed to blow up a resistor when in trouble. You should be able to get it repaired without any permanent damage. I would give Leonard at Audio Research a call and ask him what to do. He's very helpful and will even ship you parts if you want to have a repair done locally. If you can get a local tube guru to do the work (and a checkup), it shouldn't be too expensive.

Good luck with the repair.
John.
I used Chinese KT88's for years in my D250MKII with no problems. Only had one tube ever fail!
GTF
Thank you John, I took my unit back to the local dealer, they had talked to ARC as well, KT88 is ok to used in VT100 MKII, not MKIII. Instead of replacing the resistor myself, I trust ARC more in their QA and listening test. I decided to go with MKIII update, hope I had made the right choice. BTW, I'm testing my quad matched Svetlana KT88 in a friend's tube tester, just want to make sure they are OK, since my new MKIII can't use them, I would like to sell them (less than 5 minutes used). Let me know if anyone is interested. Thanks again