The designation B+ refers to the plate supply voltage in vacuum tube circuits. In most tube circuits (and in HammondOrgans) it is typically a few hundred volts. This is a lethal voltage (see HammondsCanKillYou.)
Many of the earlier Hammond ConsoleOrgans (e.g. BV's) did not produce their own B+ supply voltage. Instead they obtained their B+ from their tone-cabinet. Hammond ToneCabinets, as well as Leslie122's and other ?DifferentialInput Leslies provide B+, the ?SingleEndedInput Leslies do not supply B+.
If you have one of the Hammonds which lacks B+, and you'd like to use it without a ToneCabinet which provides B+, it's a fairly simple matter to build a suitable power supply. Or you can buy one pre-made --- Hampton makes one (model BPLUS1).
RobertHayton has some simple circuits (from BobSchleicher) for generating B+ at:
http://www.myplanet.net/x77dude/bplus.jpg.
The content of this page is Copyright (C) 2000, 2001, 2002 Geoffrey T. Dairiki and
the other authors of the content, whoever they may be.
This is free information and you are welcome redistribute it
under certain conditions; see
http://www.dairiki.org/HammondWiki/opl.html for details.
Absolutely no warrantee is made as to the correctness of
the information on this page.