Y'know, the term "B plus" might be a little esoteric to a total Noob unless some background wuz provided on how the term came to be. Looks like he's hopelessly addicted to vintage TVs
, and the term is gonna be ubiquitous to the addiction.
Anyhow, it harks back to the early days of radio, when radios ran on batteries. The tube filaments ran off a low voltage battery called the 'A' battery. The plates were supplied by a higher voltage source of 90V or more, called the 'B' battery. As radios evolved to run on house current, the plate source continued to be called the 'B' supply, and since it was of positive polarity, simply "B+". And the convention carried on into television practice.