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.
