Tube rolling gain and buffer stages?

[BadBob]

Help... I mean oops, one of the power tubes in my ARC REF10 preamp was glowing a little odd so I ordered up some replacements from Upscale Audio. I looked only at the manual for my REF10 pre and it said the power supply used 2ea 6550c tubes. But I ordered new production Svetlana 6550c (not the 'winged c' variant). When I removed the cover the original tubes are Sovtek 6550we.

Should I return them for the Sovtek "we" variant? Has anyone rolled these tubes using the Svetlana? Tima?

[MylesBAstor]

Yes based on results with older cj gear. As you know, cj has done away with cathode followers nowadays altogether.

Yes, I preferred the Svetlana 6550C, yes Winged -=C=-. I also choose it over the Sovtek 6550WE which ARC now uses in place of the no longer available 6550C. Wish I had a stock of the 6550C.

I know there are people who are in love with GE 6550A in ARC gear, I'm just not one of them. (It's a great tube in CJ amps such as the Premiers 11 and 12.) I sent a GE 6550A to ARC when I reviewed their REF 2 Phono back in 2010 and it was not a happiness: "Terrible sonics--as far outside the acceptable sonic window as conceivable" and more in a similar vein. I've read forum reports that the GE6550A works better in, say the REF 5/5SE than in the phono stages, but I did not find that.

[Barry]

To clarify, so you liked the Svetlana 6550Cs better? Were these Winged Cs? I certainly agree PS tube swaps make a big change and my discovery was made in ARC Ref gear as well. Thanks.

[Paul S]

Good question, no idea though, certainly psu rectifier valves make a difference but buffers, maybe?

[JCOConnell]

No doubt changing power supply tubes can make an audible difference, its just these follower circuits that bother me.

Then there's power supplies. Definitely heard worse after swapping out Svetlana 6550Cs for GE6550A in ARC Reference gear.

[JCOConnell]

We all know about the audible effects of rolling different brands and vintages of tubes in a gain stage. But are there audible effects when changing tubes in a cathode follower (buffer only ) stage? If so, is it as great as a gain stage?