Svetlana KT88 VS EH6550

The resistor blew yesterday and I suspect it was a bad tube. I plan to call them tomorrow and see if they will send me some new resistors so that I can intall rather than sending it back to the factory. The tech people had told me that the early Svet KT88's had alot of problems and thus they are now not recommending them. Of course they are no longer selling amps but are still maintaining them. If the 6550 is more reliable then they are probably discouraging the KT88's in order to minimize the repair issues.

You should also consider going with KT-90s.

Kevin at Upscale Audio can help you with matched set.

I just spoke with Chris Johnson at the Parts Connexion regarding the recommended tubes for the Power 3's. Chris was president of SFI and knows the product better than anyone. He strongly suggested the Svetlana KT88 tube as the best option. He said the 6550 variations do not sound as good on these amps as the KT88's due to the higher plate voltage. He is sending me new tubes and some replacement resistors. I would suggest that anyone looking to retube an SFI product contact him.

I would say the Svet KT88 is (one of) the best sounding, but not the most dependable. The Power 2SE and Power 3SE were initially shipped with those tubes, but they had problems. So they stopped and went to the Sovtek KT88.

I don't sell those tubes into the Power 2 or 3 typically, and also not into ARC amps like the VT100. I think the problem is they on occasion will draw too much screen current. We check the tubes for that, though I don't think any other place does.

With that I love the Svet KT88. But care should be taken. The Sonic Frontiers power amps have no plate fuse protection so if you make a mistake you have to go underneath and solder a resistor or two. I use them all the time in other amps. They work great in Cary's and many others.

The Svetlana 6550C is the most dependable tube we have. And sounds great. I try to read the customer when I chat with them to see if they are technically adept. If they are not, play it safe.

Hence the problem with on-line tube ordering with no concern on proper use. Gets the customer into trouble. I have wanted to put that into place, but no easy way to do it right.

Kevin, I value your opinion regarding tubes as I have bought tubes from you in the past for several of my components. I am willing to replace resistors occasionaly in order to deliver the best sound. I went with Chris's recommendation that the Svet KT88 does deliver the best sound on these amps. If I find that these tubes begin to cause me excessive problems then I may reconsider the 6550 options as I am sure you are correct in saying that they are more reliable. The original Svet KT88's that I had in the power 3 SE's lasted around 1200 hours before I had an issue. This is something I can live with. If I had issues with them every several hundred hours then that would be a different story.