I bought the KT88D and the tube just exploded! On the same amplifier I use JJ and Psvane without problems. What's worse is that the seller Tokban Audio refused to resolve the issue. It may happen that they sell a defective valve, but serious sellers solve the problem, but this one simply refused. It was the first and last time I buy Linlai. I have several Shuguang, Psvane and other Chinese brands. All quality. Linlai, on the other hand, disappointed me. It is important to note that on the official website of the brand they do not sell KT88. Would that be the reason?
OK, the Linlai KT88-D arrived. They are very well made, and all plate structures are very straight in the bottle on this quad. Very solid in the hand. I am running them as drivers in the 300b mono amps that Lynn Olson and I designed. The tubes are running about 56 mA and 270V on the plates and they are transformer coupled to the 300b grids with custom iron. So the tube is coasting along here, and these results don't necessarily translate to the sound in your traditional KT88 output tube use into an output transformer. That said, the amps ruthlessly reveal the quality and character of the driver tubes you employ.
These tubes have about 6 or 7 hours of play, so have a long way to go. That said, they sounded good from the start albeit a little thin. After 6 or 7 hours they are full, rich, and well balanced. I would say in this application they are superb tubes and I know they will continue to improve for 50-100 hours. I think they are a pretty safe bet for folks to try at this point. My 2 cents.... I have a very trusted Chinese supplier and I get very good Linlai tubes. I would avoid aliexpress or those sorts of sites. My source is JiaJia audio and I have been dealing with Helen for years now. Shipping is spendy, but I buy $1000 worth of tubes at a time so it is diluted. I would say if you can get a quad of Linlai KT88D from a trusted source for a decent price, then I would certainly try them. They cost me what the JJ would cost and I prefer these so far. Good luck to all.
OK 25-30 hours. As expected with any good KT88, they have really opened up. The other KT88 I have run as drivers in this amp is the now unobtanium Shuguang WEKT88, which was their best KT88 right before the factory shut down. The Shuguang WE series WE6SN7 and WEKT88 were very rich and full sounding. They leaned towards the warm side of things, but still had good detail. The Linlai E-6SN7 and this KT88-D are decidedly neutral sounding with great detail and very tight bass. I would not call them warm, but rather very neutral. Don't get me wrong, they are still tubes, and not solid state sounding at all. But they are not overly romantic. The JJ KT88 is a good tube, but in my KT88 amp it sounded just a little unnatural with emphasis of certain parts of the frequency spectrum. Very subtle, but designed to sound very alive and grab your attention. The Linlai offererings are just very neutral. They do everything well with great detail and slam, but they are not overly warm like the Shuguang WE series, nor do they draw attention to themselves a bit like the JJ. I really like the Linlai WE300b exact Western Electric copy. It is also a wonderful tube to my ear.
So those are my opinions. You can take or leave them. A data point for you all:)
@donsachs - a follow-up to your Linlai KT88 comments.
Do you have any experience with the Sophia Blue KT88 (vs Linlai KT88) as they are being re-introduced later this month?
I heard some Sophia blue glass when I was doing the vintage work and a fellow sent me a quad to use with his citation II amp that I was restoring. Sounded good, but I only listened for an evening and the amp had all new caps and power supply so not really a good data point. I have not heard any other Linlai KT88, just the Kt88-D. I have heard their egg shaped 300b tube and it is quite good, but the WE300b copy is much better to my ear.
I now have about 50+ hours on the Linlai KT88-D. They are stable, no issues, and the sound is stunning. Again, these are drivers in the 300b amps running about 15 watts, and not used as output tubes. That said, they appear very well made and I would expect them to be quite good as output tubes in an amp. My 2 cents... good luck to all.
I ordered a quad (top 10%) of the "Global" labeled KT88-D from Grant Fidelity - eagerly awaiting arrival. Alas, "express shipping" is S-L-O-W....
That said, GF would not reply to my question of differences between the tubes labeled "Global" vs the plain brown printed labels.
Don, do you have any insight into the differences (if any) of the 2 types of labeling by Linlai factory?
The Linlai WE 300b exact western electric copy is in my amps. We used them at the Pacific Audio Fest. They are wonderful and I stopped looking at 300b options when I got them. There may be better 300b tubes out there, but I really don't need to find one and I get them for about $750 a quad. I don't desire to spend $1500 per pair for 300b tubes. I have had 4 quads of the Linlai WE300b now with no issues whatsoever. The Gold Lion reissue was a nice tube, but in my amps to my ear the WE300b is much better. To each their own though. Both the Gold Lion and the WE300b are very much better than any of the $500 per quad 300b tubes I have heard. The Linlai egg shaped ones are actually quite good, but no match for the WE300b. Again, my 2 cents. Everyone has their taste.