6550 tubes

I really appreciate all of the comments on this thread. Has given me several options for tube selection. As a full time component level audio tech I found a lot of the new tubes like the Gold Lion KT88 Russian knock off to be unreliable, I have these DOA new out the box. I'm going try the Shuggie KT88SC and see how well these work out.
I also design amps and preamps Cunningham Audio. I'm currently working on a new 100 watt version tube amp to be out this spring. Many Thanx To all!! Robert

Sorry -- typo corrected in brackets: "Agree 100% with Jea48, especially re Upscale Audio. I've heard that the Russian factory that made Svetlana [6550] Winged "C" tubes burned down, but Upscale Audio] has a supply on hand."

My personal favorite is the original Tung Sol 6550 black plate followed by the grey plate. Another nice tube that is tough as nails is the Ei KT90 type2. The SED 6550 is a very linear sounding tube and if you like that tube the KT120 may be for you also.

If you can find them NOS GE solid grey plate 6550 tubes are my favorite 6550 type power tube. Another favorite also are NOS Sylvania 6550 tubes. I've used these tubes in a Jolida JD-502P amp at various times.

If you are going to go for KT-88 type power tubes my favorites are JJ Blue Glass KT88s and the Penta Labs solid plate KT88s. I believe Doug's Tubes on Long Island has the Penta Labs in stock.

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,

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?

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.

Agree 100% with Jea48, especially re Upscale Audio. I've heard that the Russian factory that made Svetlana Winged "C" tubes burned down, but Audio Research has a supply on hand.

As Jea48 just said, Upscale Audio burns tubes in for 72 hours and does a very good job of matching, which is very important in push/pull type amps.

Don't know the amp you are using but check out Tung Sol KT-120s. ARC dropped in KT-120s as a replacement for 6550 Winged C tubes several years ago. But be careful. Not all amps can handle the extra power draw demanded by the KT-120s.

Regards,

Bruce

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.

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.