If an SVT doesn't sound great, then it's either not turned up loud enough, needs a different cab, needs maintenance/biasing, or needs tubes swapped. They are plenty versatile in my opinion.
JimmyM said:
tubes are made in china, russia, and the czech republic.
Close...
J/J Electronics is located in Slovakia, not Czech Republic.
Shuguang tubes and the re-branded Shuguang tubes (Mesa, Groove Tubes, etc) are made in China. There's another factory in China (forget the name), but I don't think they export much.
New Sensor tubes (Sovtek, Tung-Sol, Gold Lion) are made in Saratov, Russia. Winged Cs =C= are made in St. Petersburg, Russia.
I think that covers the big manufacturers. There are some small boutique tube shops scattered throughout the world.
In the good ole days, tubes were made in USA, Britain, Canada, Holland, Germany, and Japan.