Hers's our full explanation on the tubes used in TUBE-TECH units:
The various TUBE-TECH units are not very much dependent of any specific brand of tubes.
The rule is: Any good tube that performs up to spec will work in all the units.
( The only exception is the VCA tube for the LCA2B, that needs to be selected very carefully to be functioning properly.)
Throughout the years we have been using various brands:
Siemens, EI Nis, Golden Dragon, Sovtek, Elektro Harmonix.
These days we use tubes from Shuguang in China.
Tube specifications from various factories are changing over time.
Tube Tech designer John G Petersen goes through great lengths to select tubes which meet their criteria for noise and performance.
John has tested many, many brands of tubes and currently feels the Chinese tubes they put in their new units to be superior to the other brands.
And as for the Chinese tube manufacturing, their factory is now producing tubes for many notable brands such as
Groove Tubes, Golden Dragon, PM Tubes, Ruby Tubes, Tube Amp Doctor (TAD) just to name a few.
The Chinese are estimated to produce half of the total tubes made in the world today with the other half divided between The Slovik Republic and Russia.
No longer is the words "Made in China" a bad thing when it comes to vacuum tubes.