It should not be surprising if some of the VT-231 variants sound the same as its 6SN7 proper in a vibration-free environment. The difference is that the VT-231 is a military spec version, designed to minimize microphonics in high vibration settings, but electrically identical. These tubes were originally meant to be used in WWII piston aircraft and naval vessels. Yes, some VT-231 variants sound better (the RCA VT-231 grey bottles far outperforms the RCA 6SN7GT's and the Tungsol VT-231 is, IMO, about the best there is) but, depending on your equipment and setup, there might not be as great a difference.
Tu-bee or not tu-bee... A philosophical question.
I'm looking at a tube. It's rocking back and forth right above the number keys on my keyboard as I type. It says "Raytheon" and it looks like it should be a VT-231. In fact, it is identical in every way, including sound, to a Raytheon VT-231 that I have, but when it rocks all the way around I can see that it just doesn't say VT-231 anywhere. It says Raytheon 6SN7GT, nothing more.
What should this tube be called?
Are both tubes worth the same amount of money?
Would you rather have one more than the other?
What should this tube be called?
Are both tubes worth the same amount of money?
Would you rather have one more than the other?