KT88 Tubes, What is your favorite and why

PSGuitar said:
Never had reliability issues with new tubes. Not sure why some people do, but that sucks. I would hate to have to keep changing failing tubes.
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It never fails, like clockwork for me. The only new production tubes that I get, come with a new amp. I've only bought a few 5153 iterations over the years, and in 2 of them a JJ 34 gave up the ghost.
Recently, a PRS MT100 had one of its TAD 6L6GCs redplate, the second day I had it. Took out a bias resistor. Those new TADs, when I tested them tested at 85% on my tester where 80 is minimum good. I replaced them immediately with a quad of 90s Sovtek 5881s. Those, tested at 115%. 30 yrs old, and used. Go figure.

Thankfully I have a good stash of 12ax7s, 34s, 6l6, 6550s, 5881s most of which are 15-60+ yrs old, used but test almost new.
 
I have a matched quad of kt88s from 2020 that i bought for a twin jet, but sold fucking amp before the tubes got here if someone is interested. I dont know if that was before the quality control issues. But they have never been used
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I recently did a shootout with Sovtek, Linlai, Shuguang, JJ, Mullard, Genalex, EH, JJ, Svetlana and TS Preferred Series. I’ve come to the conclusion that the differences in them can 99% be overcome with EQ. If you don’t have an EQ in the loop then I could see brand choice being more important.

Does dissipation % affect how much unique character you hear between brands? Years ago I used to rock 70% ‘cause ppl said that was best, but nowadays I set it to 60% ‘cause I realized it sounds better. I used to strongly prefer Sovtek but now I can hardly tell the difference so either lower dissipation percentage diminishes the difference between brands or I’m going deaf.
 
boltzthrower said:
I recently did a shootout with Sovtek, Linlai, Shuguang, JJ, Mullard, Genalex, EH, JJ, Svetlana and TS Preferred Series. I’ve come to the conclusion that the differences in them can 99% be overcome with EQ. If you don’t have an EQ in the loop then I could see brand choice being more important.

Does dissipation % affect how much unique character you hear between brands? Years ago I used to rock 70% ‘cause ppl said that was best, but nowadays I set it to 60% ‘cause I realized it sounds better. I used to strongly prefer Sovtek but now I can hardly tell the difference so either lower dissipation percentage diminishes the difference between brands or I’m going deaf.
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I am no expert, but i think dissipation is literally only about clean headroom. I like more so i can have louder with the sweet spot of powertubes barely adding anything. That is the sweet spot
 
In my Deliverance 60 I ran Gold Lion KT88's for a long time (one of the stock Sovtek KT88's lost vacuum within one week of purchasing the amp so I never went back to those)


Eventually switched to ValveArt 6550's and that was the ticket for me; half the price of the GL KT88 (at the time anyway) and sounded/felt best to me
 
Racerxrated said:
It never fails, like clockwork for me. The only new production tubes that I get, come with a new amp. I've only bought a few 5153 iterations over the years, and in 2 of them a JJ 34 gave up the ghost.
Recently, a PRS MT100 had one of its TAD 6L6GCs redplate, the second day I had it. Took out a bias resistor. Those new TADs, when I tested them tested at 85% on my tester where 80 is minimum good. I replaced them immediately with a quad of 90s Sovtek 5881s. Those, tested at 115%. 30 yrs old, and used. Go figure.

Thankfully I have a good stash of 12ax7s, 34s, 6l6, 6550s, 5881s most of which are 15-60+ yrs old, used but test almost new.
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The TAD's that were in my MT100 also red plated. PRS sent me a new set of Apex matched JJ 6l6's under warranty which honestly have been going strong and sound great.

For KT88's the only thing I'll say is stay away from the KT88 from JJ, I tried them in my Mesa Strat 500 and they sounded really bad. I ended up putting SED 6550's in it and sounds amazing.
 
jasonP said:
The TAD's that were in my MT100 also red plated. PRS sent me a new set of Apex matched JJ 6l6's under warranty which honestly have been going strong and sound great.

For KT88's the only thing I'll say is stay away from the KT88 from JJ, I tried them in my Mesa Strat 500 and they sounded really bad. I ended up putting SED 6550's in it and sounds amazing.
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As good as the Wing C 6550 is, and they are good, the GE 6550 is even better. In the 2203s anyway.
 
Racerxrated said:
As good as the Wing C 6550 is, and they are good, the GE 6550 is even better. In the 2203s anyway.
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Agreed. Haven’t actually tried in them in my Marshall’s, but in many other amps I’ve had GE 6550A’s were the best IME followed by the RCA’s, Sylvania’s and Coke Bottle US Tung-Sol’s as my next favorites. The JAN Philips are also very good. I like all the old US 6550’s more than the Winged C’s, although the pre-Winged C’s sound a bit better IME, but still prefer the US 6550’s
 
Exo-metal said:
Old Svetlana KT88's were the best but that was long ago.
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For KT88’s the very best I found have been TT21 GEC KT88’s, but a matched quad would be over $1200 and they need adapter sockets. After that regular GEC or Mullard label (same thing) KT88’s and ‘90’s Tesla KT88S’s. Also sadly hard stuff to come by. They sound even a little bigger than my Russian Tung-Sol KT120’s when I compared them
 
boltzthrower said:
I recently did a shootout with Sovtek, Linlai, Shuguang, JJ, Mullard, Genalex, EH, JJ, Svetlana and TS Preferred Series. I’ve come to the conclusion that the differences in them can 99% be overcome with EQ. If you don’t have an EQ in the loop then I could see brand choice being more important.

Does dissipation % affect how much unique character you hear between brands? Years ago I used to rock 70% ‘cause ppl said that was best, but nowadays I set it to 60% ‘cause I realized it sounds better. I used to strongly prefer Sovtek but now I can hardly tell the difference so either lower dissipation percentage diminishes the difference between brands or I’m going deaf.
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Which ones of those brands did you like the best without an EQ in the loop? I still see Gold Lion recommendations, and I think Bogner's been using EH, but still have some concern with quality of newer KT88s.
 
I would put up the Svetlana's from way back in the 90s against any KT88 and the comparison would be impressive against the ones you mentioned. They were so good I would put money on it.
 
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Exo-metal said:
I would put up the Svetlana's from way back in the 90s against any KT88 and the comparison would be impressive against the ones you mentioned. They were so good I would put money on it.
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I may get one to try. I can tell you at least when I compared directly the ‘90’s Pre-Winged Svetlana 6550’s (which I generally prefer tonally to KT88 counterparts) they weren’t to me in the same league as the KT88’s I mentioned before. The TT21’s are a different design with exceptional detail and more extended lows and highs that I never heard in other KT88’s including their normal GEC KT88’s and the headroom/power is noticeably greater than any other KT88 I had when compared. Also the Tesla KT88S’s appear different physically and sound massive. I could be wrong, but I’d also put significant money on my stance lol

In general, across the board none of the ‘90’s Svetlana’s I’ve had (EL34’s, 6L6GC’s, 6550’s) excelled in the most complex tone vs other my older brand vintage tubes, but have lots of punch and a robust low end. I guess the Tesla’s though also are like that IME
 
PSGuitar said:
Never had reliability issues with new tubes. Not sure why some people do, but that sucks. I would hate to have to keep changing failing tubes.
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I don't either. I don't believe the old tubes are better anymore.

I think it is more about the individual tube and the rig you are using them in. This has been my experience.

I have vintage KT88 and 6550 here.
They really don't seem any better.

By the time a tube is 30 years old /1994 it starts to loose vacuum. Some of mine are from the 60's and 70's.

I tested all my tubes a few years ago. Only about a dozen showed up questionable or unusable out of hundreds.
 
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