2. amps-preamps
  3. 1198634468

Expected hours for JJ Tesla KT88?

Folks -
In March 2007, upgraded stock Sovtek 6550 power tubes to JJ Tesla KT88s. The Sovteks had lasted 5 yrs or so (and still have some life left). A KT88 (JoLida 502B v8 position) failed in Sept after about 400 hours. A second (v7 position) began glowing intensely red today after about 700 hours. I powered down before anything bad happened. I'd heard KT88s were less robust than the 6550s. I do take care with proper biasing. Curious what the experience of others has been with KT88s and JJ Teslas in particular. Thanks in advance for any feedback.
128x128ghosthouse
hanki
27 posts
 
I have no experience with the KT88's but, I've used JJ EL34's and had the same problem as you. I switched to SED winged "C" EL 34 tubes and have had no problems at all. From what I've read, JJ tends to have a lot of quality problems. They sound good but, I'd stay away from them and change them all immediately before they damage your amp.
ghosthouse's avatar
ghosthouse OP
4,296 posts
 
Hanki - Thanks for the input. The JoLida seems pretty robust. I'm inclined to run the JJ/Teslas for the time being(I have spares). As funds permit will consider buying a set of SED Winged 'C' KT88s. SED Winged C was on my short list originally. One of the guys at the Tube Store had recommended the JJ/Tesla KT88s and I was very happy with the sonics (compared to the stock/5 yr old Sovtek 6550s). But <<1000 hrs just doesn't seem right. Who are you buying your tubes from? I'd been using the Tube Store (Canada) but recently ordered from Doug's Tubes and was happy with his prices and promptness. What about you? Best wishes for a Happy New Year.
Post removed 
More to discover