Preferred Series KT88 Power Vacuum Tube (Matched)

One or more were noisy, which seemed to burn off and then happen only occasionally. At less than 3 months one burned out in rather spectacular fashion. The Tubestore replaced under warranty. Then another burned out same way. So 2 tubes out of 5 in less than 6 months.

Compared to some old spares on hand, the Svetlana have less glare, and JJ have a noticeably greater sense of ease, almost silky refined midrange and treble, and quite a bit deeper and more palpably real sound stage. Quite a surprise considering how old they are, years, with probably two thousand or more hours on them.

I'm giving three stars as on sound quality they are about average, and assuming 2 bad tubes was just my bad luck.

Amazing! I bought a used Rogue Tempest II, recently. It came with KT88EH (ok), Sovtek 12ax7 (eh), and no name Chinese 6SN7GT. I was going to replace the smaller tubes first since they were the cheapest and worst, but I decided to go all out on the Black Friday sale. I got the TTS KT88s, TTS 12ax7s (7025), and Tungsol 6SN7GTBs.
I'm too old to spend the time and energy on A-B testing so I switched out all the tubes and fired it up. With nothing more than a warmup the sound difference was like an entire system upgrade. I've been around audio a long time (and I really do not like the general direction the industry has gone) and I was a professional classical musician for many years. I would not have though that much improvement could come from a moderately priced tube upgrade.
The sound is better in every aspect. And not by a little bit.
Detail vs warmth? Don't settle!
If the detail is not revealing better music, then what is it really doing?

These sound fantastic in my ST120. I got the kit that shipped with the Russian 6550s and after 60-120 hours I wasn’t hearing that wide 3d soundstage I was wanting. The 6550s sounded really good but I felt the right tube could really open up and fill the room. These KT88 tubes do that very well. Amazing clarity across the spectrum without harshness.

I just replaced the stock KT88s on my Bogner Shiva Anniversary with a matched pair of these and the difference is huge. So much more life and sparkle. So much more high end extension and sweet mids. Both my Strat and Pensa MKII now out-chime my outdoor chimes. Totally worth the price. Couldn't be happier..

I initially had issues with these tubes being to to bassy sounding, but i have a handful of preamp tubes, and decided to go back, and experiment. I had to take out the JJ 12ax7 out of V1, and went back to the Tung Sol for that position. In the V3 position i like the Tungsram ECC83 for my Coreblade. I find that these three preamp tubes really work well together, and help the mid knob get a airiness type mid range that doesn't overly affect the bass, and resonance adjustments on the amp. With my previous EL34b power tubes these preamps tubes just wouldn't' work because they eliminated all the bass frequencies, and since I added the KT88's I was able to get all those bass frequencies back, which is awesome. I find I can turn up all my amps tone adjustments, and affects adjustments to the max settings, and still get a good sound. I don't have nearly as much percussive pick attack as i did previously, but that is more because I replaced my Jensen Blackbird/ Tornado speakers, with Warehouse speakers ET90, in my Port City OS Wave 2x12, which i find is brings out smooth lead tone instead. In order for me to get any semblance of percussive palm muting attack on my A standard tuned Reaper I have to dial back the resonance,, and bass parameters a lot. I might possible in the future try out a Vintage 30, after i try adding a compressor to my sound to see if i can bring the percussive back for the certain rhythm I like to use it on.

I moved the Dimarzio D activator pickups on my guitar as far away from the strings as i could, and raised the Poles as close as i could get them to the strings to help further reduce the bass that i get from my 27" scale mahogany Agile Reaper. This helped clear up the bass on the Bridge pickup some, but i still have issues with the neck having more bass then i care for, so I think I'm not going to use it much if ever. I found with the KT88's i can get a really good warm but not dark lead tone with the bridge pickup on It's own, with some minor amp tone adjustments which is sweet.

Overall I'm pretty happy with the sound I'm getting with my amp after these changes. They have been a great improvement.