the castle X series of esc have BEC voltage adjustment of 5.5, 6, 7.5 and 8v.
and I've read in other forums that the 7.5v option is actually close to 7.25v.
my question is will a 7.4v servo work with the 7.5v option on the esc?

thanks

Short answer, yes. It will work. Long answer, the way servos have historically been rated is by the nominal voltage of the battery they can be used with. So 4.8/6v means it can be used with a 4 or 5 cell NiMH battery (1.2v/cell). For a 7.4v servo that means you can operate the servo off a 2s lipo (3.7v/cell, 7.4v nominal, but 8.4v fully charged). Hope this helps.

thank you sir