I've tried them both in the past but forgot how they differ, sonically. I believe one can handle higher plate voltages than the other. And one sounds more like a hybrid EL34/6L6 than the other. But I don't remember which is which.
I use BHT's in my Bogner XTC 20th EL34 and think they sound great. No experience with the STR's, sorry. I like the BHT better than winged C's and even Gold Lion KT77's in that amp. Fuller, better more even mids and non harsh top end at all volume levels.
After looking back at some old threads, the BHT are the ones that can stand higher voltages. But they are are both very similar tubes. I have the STRs in one of my Peters amps right now actually. I really like the EH EL34 as well. Very similar to NOS RFT/Siemens.
Higher screen voltage capabilities would be the more logical benefit of the BHT. EL34's in general are spec'd for 800vdc Max plate voltage, so higher plate voltage handling would just be a gimmick.
Higher screen voltage capabilities would be the more logical benefit of the BHT. EL34's in general are spec'd for 800vdc Max plate voltage, so higher plate voltage handling would just be a gimmick.
It's been a long time since I tried them, but I seem to remember the STRs emphasizing the highs a lot. Depends on your amp whether that is a good thing. My preference leaned towards the BHTs.