What about JJ KT88 tubes?

I've used JJs (not 88s however, mostly El84s and 6V6s) in guitar amps for years and they're great.

Jedinite24...my 502 bias LEDs vary mightily depending on what time of day it is and what is going on in my house (laundry, dishwasher). None of my tubes drift much but those LEDs have become something of an "available juice" sensor, even though none of my tubes are dying yet. I check things with a meter just to be sure and it's never changed more than a tiny fraction and always well within the Jolida recomended range, regardless of tube type.

I've used Gold Lion KT88s for years with no reliability issues.

I've been really enjoying the blue glass JJ KT88 power tubes in my Jolida JD-502P amplifier. I've paired them with a pair of Mullard CV4024 type 12AT7 tubes and JJ 5751s. Very clean tone and wonderful bass.

I hope others can give this power tube a try in their amps. They aren't the most expensive tube out there so I'm guessing they may get overlooked by the audio community.

One thing I'm wondering about with these tubes when they are biased. With my Jolida amp as soon as I turn it on the bias lights on the Jolida turn on within minutes. With other KT88/6550 tubes and even the Tung Sol KT-120 power tube the Jolida would reach proper bias in about 20 minutes to 1/2 hour. Has anyone experienced this as well with their amps and JJ KT88 tubes?

Try the SED 6550. I like the JJ, but the sound of the 6550 is even better. The GL is a bit compressed sounding with my amps. Not a bad sound, just a little un-dynamic. I like the SED 6550 first, next the JJ, next the Sovtek KT88.

Thanks for the inputs all. I have been using the JJs and have been pretty happy, but am always looking for something better. The system is my 2d system in my bedroom. I have used the Treasure 6SN7 in my main system, and I really do like the sound (and these are teh blue glass prototype version, not the better black bottles). Appearance was a major factor in the amp selection, as I thought it would look good with my old art deco furniture, plus it had gotten a lot of good press. I was happy to see that at night, the tubes cast a big V-shaped patch of light on the wall, looking very art deco. Since this is a second system, I'm willing to sacrifice some sound quality for appearances, although I would like to choose the best sounding tube that still looks good.

Have used JJs , SEDS and GL reissues, I prefer the overall sound of the GL Reissue to those , no problems with reliability. That said, and while it is your choice on seeing the inside of the tube, the Black Treasure to my ears betters the rest, ex the Psvane which I haven't used, by far musically. If it is the music you're after, suggest a listen to the BTs

I've been using JJ KT-88's in my Quicksilver V4 Amps (4 per channel) with no problems. No biasing issues as well. Sounds great.

I've got a quad of JJ KT-88 outputs in my Image 65i. They've been in service for over a year with zero problems. Bias drift has been minimal. I've been very pleased with the sound quality.