Anybody tried KT120 tubes on Conrad Johnson amps?


I use a pair of Conrad Johnson Premier 8A mono blocks. I was using Svetlana 6550 tubes on it, I switched to Tungsol 6550. Then Tungsol announced KT120s. Tungsol says it is suitable for 6550 users, but CJ says use only 6550s. Did anybody have an idea?
john_kns

Showing 2 responses by br3098

This does not directly answer your question, but when I owned a Premier 11A the previous owner had been using KT-88s. He thought that they sounded great but wondered why he kept blowing fuses and why the tubes needed frequent biasing and replacing so often. Although it metered OK, the amp sounded so bad I thought that it might be defective. On a whim I ordered a quad of EH 6550s and after replacing the KT-88s the amp sounded wonderful and no more blown fuses.

I used to have a Japanese customer, a very old school and old money guy who was raised very traditionally. When we would go out for sushi he would shudder every time I would add wasabe to my soy. He would admonish me "if the Itamae (sushi chef) wanted you to have more wasabi, he would have added it to the sushi!"

Long story short - I don't think that it pays to try and second guess the designers of the amp.
Sparky, not to sound argumentative; but I do not think that upgrading the caps in an amp is the same as swapping a non-spec'd power tube. Capacitor technology has improved significantly in the last 30 years, and there is little to no risk in replacing old caps with new ones of the same (or compatible) values. But that's not the same as a power tube substitution, which in many cases compromises the integrity of the system design.

I'm not implying that it should never be done, but in my book it's an all bets are off decision. I'm not interested in being an unpaid beta site with my good tube gear.