6550 tubes

Penta Labs solid plate (Shuggie KT88SC) was the only current production 6550 that I liked. Other than it, I liked only old stock tubes, such as Tung Sol or Philips ECG (Sylvania) 6550.

Hello,Out there.Has anyone found decent 6550 tube,I have tried several,Like Gold Lion KT88,Tung-Sol 6550 EH6550 Russian knock off, all of which failed within one month or DOA out of the box.
Fact is the only 6550 I found that did work for more than a month was Valve Art 6550 but has filament noise issues.
Any info would help.

I think the problem is not the tubes but rather the amp or maybe you are not biasing the tubes correctly.

What amp do you have? Manufacture, model, and series?

I have used EH tubes in my ARC VT50 with good results. Tube life of around 2000 hours.

I also have had good luck with Svetlana SED "Winged C" 6550C from Upscale Audio.

The SED set installed in the VT50 at present probably have 200+ hours on them.

The thing I like about Upscale audio they pre burn in power tubes for 70 hours. For me that saves having to check and re bias the tubes several times during the hours of burn-in than with power tubes that are just new out of the box.

If your amp is not an auto biasing type amp it is important you turn down the bias pots before installing the new tubes. Failure to do so can damage new power tubes.

Second on the Winged 'C' 6550s, from Upscale. It's hard to beat Kevin's testing & matching. I used to buy his NOS Sylvanias, but they've been gone for a few years now.

Hello,The problem here is not the amp I'm using. I am a certified electronic tech,I just tring to find a decent 6550 that works without any issues. I have tried several that are in production these days but found them to be not so good. I have stock on new old stock 6550. I do agree the SED 6550 are worth while do work well in AR amplifiers. Anyone try any of the new KT120 or KT150?

350b,
When I was primarily using my push pull amplifier (6550/KT88) failing tubes were a problem with various brands. I had the most sucess by far with the SED Winged C 6550. In contrast, my SET amplifier uses the 300b tubes which are 100% reliable(so far after 4 1/2 years) and are true work horses in comparison( and sound much better).
Charles,