Sovtek 6550 - Can they really be THIS bad???

can't tell ya about 6550 sovts but EH to my experience has a record short life that may be very distructive to the component circuitry.
i've used eh EL34 and will never place them again in my VTLs. i now use either svets or yugos. during 1+year period measuring the bias i found that it didn't change even slightly.
therefore i suggest
#1 ask manufacturer if it's OK to go with EH since some of the brands are OK... i assume that EH lack the lifespan to all other tubes significantly in any component
#2 find yourself the best match for performance/reliability and nevertheless budget as well.

Come on, Trelja you been around for awhile. "new Jadis today." Can we say burn in time :) I wouldn't even look at rolling tubes till 200 hours of burn in.

I have Soveteks el84's in my Yarland with no complaints.

BW MaxxC

A few years ago I changed the Sovtek 6550s to JJ Tesla KT88s in the ARC VT130. Wow, the musical enjoyment was dramatically improved.....until a tube blew. These KT88s did not seem to have a very good reliability. Several went out around the 6-month mark. And unfortunately, when they did, they took out a power resistor in the amp in the process. It was easy to resolder in a new one, but it was a hassle to put up with these tubes. So be forewarned about this issue. Perhaps they have imporved over the last few years.
John

EH is made by Sovtek, in case you didn't know. Some EH's are said to be selected as the top-testing tubes from regular Sovtek runs, others seem to be exclusively EH offerings (the gold-pins, and some of their "copy" tubes like the 6CA7.)

That said, I've owned Sovtek KT88s and thought they were pretty bad, but I could be happy with their 6922s (a preamp tube.) For EH, I've owned the EL84 (okay), the EL34 (not very good) and the 6CA7 (fat bottle EL34 - better, but still prefer KT88s) as well as a couple preamp tubes I haven't any memory of. Svetlana (originals) and EI (Yugo) beat Sovtek and EH in all encounters I've had, though I still remain surprised by the Sovtek 6922 - mainly for their bass impact.

That said, these are all opinions, and system matching of course always plays a big part.

maxx makes a good point yoy need to let the unit burn-in for sometime before you start flipping tubes.

Chuck