GE 6550's

Svetlana 6550c is the best tube not only the cost but the quality. I have used the 6550c in my JADIS JA500 instead of the GE6550 the sound is good and the tube is much stable. If Svetlana company can make the good matching service eg. 12 to 24 tubes matching I believe they can have much more business.
Finally matching power tube is the key point to drive our power amp in full power. Even somebody specialist told me this is not necessary but I don't think so.

I have 2 Audio Research CL60 Amplifiers.
one uses GE 6550 and the other one SV6550c, GE tubes sound a little bit better in Bass but SV6550c is a very good tube for the price.
Audio Research uses the class AB1 on CL60 meaning that power tubes are not used at 100% of capability.
Regards
Laurent

I had GE 6550's in my CJ Premier 11a. I thought the Svet 6550 was an improvement. I use the Ei KT 90 now because of a little improvement in the bass. I think the Svet is a great tube for the money.

Have Fun

the GE 6550 are all NOS. Conrad Johnson uses them quite a bit in their amps had premiere 8's which uses them never tried other brands. Is a interesting question though how they would compare to Svetlana's which my VTL's use

I don't know if GE is still making 6550s, but when I got my Jadis amps in 1990 they were and I had their 6550s in my amps. In the Jadis equipment, the GEs could not hold a candle to the Philips 6550s I got to replace them, nor to the Svetlana 6550Cs I used as well--they were far coarser, brighter and harmonically thin (Michael Gindi in his Sounds Like review of the JA 80s advised that you remove the stock GE tubes ever so gently and throw them into the nearest ocean!). And Tung Sols, if they're the real deal (and there are fakes out there), are light years better, approaching the sonics of my favorite Gold Lion KT88s. Now if GE is still making them, maybe they've improved over time, but at least in my Jadis equipment they were at best ordinary; haven't heard them in other designs. YMMV.