time to discuss kt-88's

I have used Svetlana and Sovtek KT88's but haven't tried the others yet. I found the Svetlana very clean and clear in the upper mids and highs (very impressively so) but a little thin in the bass and lower mid range. This was in a SF amp. I tried the Sovtek's in the same amp and was unimpressed until I changed the small tubes from Teslas to EI6dj8's - this brought the Sovteks to life and they have been in the amp in this combination for over a year now. I'm encouraged to try the EH's .......

I did not have such luck with the Svet KT88's regardless of the small tubes. I presently use Svet 6550s & JJ 6922's in my SF mono's which gives me a very balanced and detailed sound w/o excessive high end energy. Caveat - I focus on rugged tubes in my amps and have avoided some of the popular, but less reliable stuff. I hate lugging these beasts in for repairs because of a blown tube.

I recently traded my JJ KT 88s from my Audio Aero Capitole amp into my McIntosh 2102 amp just to see what would happen. the Svetlana Kt 88s made an amazing improvement to the Audio Aero. so much so that only now do I realize just how wonderful this amp sounds. I got on line and bought another set of Svetlana KT 88s to put back into my McIntosh. While I was at it I changed out most of the rest of the tubes in my system.

Anyway, you will find lots of support for the Svetlana KT 88 tube and perhaps even more support for electro harmonix which I have not yet tried.

I really like my Electro Harmonix KT-88EH in my ARC VT-50. The bloom I enjoy without the slight dryness of 6550. Just my 2 cents.

I'm also running EH KT88s, 16 of them, on my ASL Hurricane monoblocks. A worthy upgrade to the stock tubes!

I have a suggestion of another avenue. I have tried Sovtek, Svetlana, JJ, and other KT-88's in the past in my Sonic Frontiers SFS-80. I mention this due to it using a pair of output tubes per channel as well. I was constantly tube rolling and was talking with Kevin @ Upscale Audio and he suggested I try Ei KT-90 type III tubes. He also warned the drawback of taking 400 hours to burn in and fully open up. Well, after tracking hours and about 385 hours into play time on the new tubes I was ready to give up. The mids were a bit analytical and not as open, the bass prowess was much better than any KT-88 I had tried, and the top end was clean and extended. Yet without the mids being open and relaxed, why have a tube amp? Uncannily a few days later while in the office, I got off the phone and noticed the piano (George Winston) sounded THERE... and I was down the hall a few rooms. I kid you not - 412 hours logged and there was a transformation! The sound was what I was searching for over many, many tubes. Overall, the bass was the most controlled and defined, the mids were open, airy, hamonically correct, with clean & extended highs. They were the most neutral of the lot and the least colored. The Ei KT-90 type III's also produced the best macro and micro dynamics.

I will mention the midrange was best with NOS GEC (Genalex) KT-88's from 1966... however quite expensive and a bit colored, with sloppier bass and highs a bit rolled off.

Currently I ordered my Quicksilver V4's with the Ei KT-90's from my experiences in the past. I haven't questioned my power tube choice once.

Some find the KT-90 to be more "analytical" sounding (and THEY ARE for the first 400 hours or so) but after that it seems to be extremely neutral. I tend to prefer to use NOS Mullards in the preamp, or a tube that is slightly warmer to "tune" the overall sound to your preference. That way you get the best control of bass, dynamics and a neutral power tube, and can tube roll relatively inexpensive on the preamp tubes.

You may want to make a call to Upscale Audio and get their advice on KT-88 / KT-90 comparison.

Good luck on your search!