6sn7 tubes for Atma Sphere amp

Congrats Glory! I have the Zu Definitions and use M60's. You are going to love the S-30!

In the past I've tried older (1950's) NOS Sylvania and RCA, preferring RCA's in the top and bottom half of the cascode voltage amp positions (V2,V1 respectively). These are the two most sensitive positions to affect sound.

Don't even bother spending good money on the constant current source tube (V3); I've never noticed a difference in this tube.

The 3rd most sensitive position is the output section driver tube (V4). This must be a GTB or GTA tube due to higher voltage. I have noticed an improvement with old (1950's) Sylvania GTB's here, but it would be the last place I'd upgrade. Talk with Andy and Vintage Tube Services...he's very helpful.

Good luck and enjoy!!

Jordan

I have a pair of MA1s, and after much rolling and agonizing, I have settled (for now) on RCA smoked glass for CCS (first tube), Sylvania WGTAs for second part of cascode (Not sure if it's top or bottom), Shuguang Treasure for first part of cascode, and Tung Sol GTBs (or are they GTAs?) for drivers. The Shuguang Treasures are every bit as good as the old tubes, but you still need to mix them all judiciously to get the best results. Too many Shuguangs were too bright, too many WGTAs were a bi tplodding, etc.

I would ask Ralph this directly to get his views as well.

I would say change out all 6. Compared to the new production (affordable) Russian and Chinese tubes, the old tubes and Shuguang tubes sound more 3D and less glarey. The stock tubes should sound very nice, but specialized tubes should adda lot of depth to the soundstage, and a more natural timbral balance. I didn't find any one tube position that didn't affect the sound, be it gain stage, CCS, or driver. You could argue that some affect it more than others, but it's hard to tell. If I had to say, I'd say the CCS tube has the least impact, but it does have noticeable impact. Or I'm delusional.

This is a super old Thread if possible I would like to revive it?