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

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

Hi Trelja. I assume this is the new DA60? And it's been burnt in? The JOR didn't sound great for a week at least, and then when the store replaced all the KT90s in response to only one being faulty it took another few days just for the tubes to sound fine again.
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I recently plugged in the old ARC D125, which has eight 6550Cs, Svetlanas, and it sounded as good as I remembered it to be - different to the JOR obviously, but good - the only other brand of tubes this ever had were old GE 6550As, and the Svetlanas killed these.
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All the best, Rob.

I recently bought a pair of used VTL 750's from an authorized dealer who had completely re tubed these amps with matched Sovtek 6550's.

These particular tubes were TRADE MARKED as "Svetlana" which are the same tubes as Sovtek / Electro Harmonix for those that don't know the name Svetlana was bought by a large distributor.

The dealer said they had 200 hours on them and testing with my Hickok 752A tester showed no shorts, no gas and "new" transconductance readings.

After listening to these for about a month, and unable to get rid of high frequency distortion and dissatisfied with imaging and dynamics, I replaced all 24 Sovtek/Svetlana 6550's with new SED Wing C 6550's.

The upgrade was almost equivalent to replacing the amps. Everyone who visited the next Tuesday listening session (with only 10 hours on them) asked where the upgrade came from.

Can't wait to hear what the Wing C can do when they are completely settled in. I think this is the best new 6550 around and as others have already commented, the Sovtek may be the worst.

If anyone wants these Sovtek / Svetlana, I will be practically giving them away. Look for on an ad at Audiogon soon.