Audio Research amp's retubing experiences

For NOS, I have had good luck with Vintage Tube Services and Brent Jesse.

Anyone tried the BLACK SABLE SEDs 6550C instead of the regular ones ?

Tube Depot carries them at a 100% permium.

I finally choosed to replace, for the first act, the little tubes inside, the12+12 sovtek 6922 with mullard military grade nos and telefunken nos for the input tubes.
The sound improvement is no less then dramatic... the amps are quite not same.
I am speechless.... I suggest to try the same to all arc owners!!!

I just purchased 12 of the reissued Tungsol 6550's for my CJ power amp and they sound very good top to bottom with a good sound stage. They replaced SED winged C 6550's, which replaced ElectroHarmonix 6550's. All of these brands produce quality sound, but I preferred the Tungsol's. If you need to save the $$$, try the EH, it's a good tube and they are reasonably priced. I've read that the cryoed version of the SED 6550C wasn't any better than the regular version. Don't know if it's true, but I wouldn't want to spend all of that money to find out that it was only hype! Good Luck!

Although the AR dealer here in Holland adviced to stick with the original Sovtek 6922 for my LS-2 pre I decided to play around with it, helped by a friend who graciously lend me two Philips tubes, a Gold Aero and a Sylvania. All sound different, so it's a matter of taste. I prefer a JJ I bought. It just shows you can 'tune' the AR to suit your taste and system.