tube upgrade for first sound


Has anyone been able to improve on the stock tubes in the First Sound preamps? I was thinking about trying the Russian 6H23. Any thoughts? thanks
84audio
an old thread that i would like to add to:

Stock: no sluch, but a bit cold to my ear, not as transparent as others.

Siemens 7308 Gold Pins (Emmanuel's favorite - i got from stewart at santuary of sound)): awesome imaging and soundstage - very quiet and refined. Maybe a bit analytical if im listening to female vocals. My brain loved these the most, my heart the least

Phillips Miniwatt pearl cryo's 6DJ8 (from www.tubeworld.com) 1959 german made: the opposite of the Siemens: warm and smooth as can be. Smaller soundstage, just a bot rplled off and less transparent than the Siemens, but the smoothness and roundness of the notes, it's emotional impact (esp at night with a merlot listening to vocals) is really unbelievable; handily eats the other tubes for dinner on the right matl.... These are what i keep coming back to, though clearly not as "hi-fi sounding" and not as good at rock or complex jazz. My heart loved these the most, my brain the least.

Finally Amperex PQ 6922 white lattereing D getter from early 1960's (got here on AG from Sam): a cross bwetwen the Simens 7308 and the 6DJ8's. These are my all-around winners, though my heart still falls hard for the 6DJ8's warmth, and depending on maoood and material, I'd prefer the reference quiet and refined sound of the Siemens.

If anything, im learning that tube rolling is like everything else in life - there are no absolutes, just trade-offs.
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tvad - mine are same as yours. PQ white lettering, nt pinched waist. I'd like to also get some pinch waists, but have yet to see any for sale.....
To calrify again - my PQ 6922's are the "D getter" version - early 1960's production.
ok - so two more simple tweak considerations for First Sound owners. Maybe this has been covered already, but it bears repeating, i think...

1) Aurios isolation/decoupling bearings - clean up and solidify the sound very nicely. Emmanuel recommended them, and as usual, he is right on the money....

2) straight into the wall. I found my Hydra robbed a bit of the inner sparkle and life.