atmasphere 6as7g output tubes.

I would like to know if anyone has compared the Sovteck to the RCA 6AS7G's and what their finding were?

Sure- in our circuits the American tube makes more power and is less reliable. This is particularly true of the GA variant which should be avoided entirely due to being particularly unreliable.

This is no small amount partially due to the fact that we employ a fixed bias scheme rather than self-bias. The American RCA is not spec'ced for fixed bias operation while the Russian (and Chinese) tubes seem to have no problem with this. But we have also found that the American tubes hog current more easily (which is why we suggest that they only be used in our gear if that gear is a MkIII series or later). In addition, the GA variant has a smaller grid heatsink, and since we employ Class A2 operation (where grid current can flow during part of the AC waveform at full power) the grid of such tubes can warp easily and cause an arc.

So we recommend if you want the best reliability, to use the Russian power tubes.

Old thread but if I may resurrect this.

Conditioning some RCA 6AS7G
1st Ralph (as always) he is right there is a lot of trouble to go with the American power output tubes on his amps, the Russian power tubes just work I have never seen a Svetlana arcing, already seen in the last 2 days 4 rcas arcing.
Can't comment on SQ yet but preliminar testing sounds to my ears in my system very close Russian vs American, kind of a Rocky IV

Currently cooking 28 rcas.

Question

If the tube was arcing with B+, does the conditioning process could remove after 4 days the arcing? Or once the tube arcs will always do? One GE specifically arced heavily to the point it smoked.
After 96 hours on standby do you apply B+ or do you shutdown, apply standby and then b+?

Honestly I just want to finish this batch testing, I am dying to put the Svetlana right in but don't want to let this opportunity pass specially if I have the American power tubes.

Once B+ is applied to a new tube, the preconditioning process is ended. So You don't ever apply B+ until the tubes have finished the preconditioning period.
However once that is done you can apply B+ right away. 

I've yet to see a GE that was trustworthy- I'm guessing that was not a 'G' but a 'GA' in the bantam envelope. GA's of any brand simply can't be used- they grid heatsink is tiny relative to the G variety and so the grid easily warps due to overheating.

Conditioning completed, the tubes which were arcing before still arcs, with the exception of the GE, which is a G not a GA but I don't trust it so I retired it. Listening to it, I can't tell if the RCAs are better,
More powerful yes they are, I can run the middle switch on the MA-1s on the down position and this is with only 12 tubes
More transparent, could be but I can't confirm need to listen more
BUT highs seems to be recessed and veiled a little, less detail which is a big drawback IMO

I guess Svetlana vs RCA you have to compromise on something, and I also guess your "bias" is tailored to the Russian tube not the RCA

I really don't like to give up on things but in my case since I have high sensitivity impedance speakers it is not worth the trouble going with the RCAs, this is a preliminary conclusion, I do have to test more.

I guess Svetlana vs RCA you have to compromise on something, and I also guess your "bias" is tailored to the Russian tube not the RCA

They both bias to the same point.