Phono preamp tube rolling.

Chelmers would be relabeled tubes from a large maker - could be USA or China. Probably USA if small signal. I had an old Hagerman Trumpet (wood tower type) that was supplied with Chelmer 6072 (12AY7) which looked like they were either old-stock Sylvania, RCA, or GE black plates.

The 6SN7 Tubes I have retained for use are Kenrad VT231 Black Glass and a Sylvania GT Tube.
These are different in their presentation as an interface where they the input Tubes on 845 Monoblock Power Amp’s.

I would very much like to try other Vintage, and will most likely return to this when the Mono’s are converted to a Balanced Design.

I have yet to hear any bit of kit made by Zesto that did not sound better than good and often great.

No significant sound differences rolling tubes in a clone of the EAR 834 phono preamp.

Tubes used: Bogen/Mullard, a Mullard ECC81 (in V3? The buffer stage, I believe), JJ, Brimar, Electrohome.

The 3 tubes in this preamp do not have to be matched.

KenRad VT231GT is also my favorite 6SN7.
ECC33 is not the same electrically as 6SN7.