Das stimmt so nicht. Schaut mal, die Großmeister von Fodera bieten das sogar explizit als "extended b" headstock an!
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Belege:
Mitarbeiter von Fodera dazu:
A lot of it has to do with the relationship between the transverse and  longitudinal vibration of the string.  The relatively gentle angle over  the head stock doesn't necessarily entirely stop the longitudinal  vibration of the string...so the actual length of the string as it  vibrates in the longitudinal mode is increased, and hence the frequency  of that mode is lower.  If that frequency happens to wind up being a  multiple of (or a consonant part of the overtone series of) the  transverse mode's fundamental, it will have a more synergistic and  supportive effect on the overall sound of the string.  You can read more  about this...which is fact, not theory...at the link below.  Bear in  mind that in a piano, the strings are sharply cut off where on a bass  the strings make a fairly gentle angle over the nut and a B has much,  much less tension than a piano string and hence less down bearing.
Seine Quelle:
http://www.speech.kth.se/music/5_lectures/conklin/longitudinal.html