On my TV-7D/U there is one setting for 6dj8 and another setting for 6922/7308/CV2492 (the bias is 21 for these three tubes and 20 for the 6dj8).
Minimum values are also different between 6dj8 and 6922/7308.
12au7/5814/CV4003 - the same.
12at7/CV4024 - the same.
12ax7/CV4004 - the same.
Not familiar with the 750.
DeKay