Separate head and speaker cabinet systems, often referred to as piggybacks, became a solution in the early 1960s, but it also negated the portability of the combo.
In 1962, Ampeg updated the B-15N with a solid-state rectifier called the B-15NB and introduced their famous “blue check” vinyl covering to their entire amp line.
Ampeg went back to a tube rectifier and changed to a printed circuit board in 1964 (B-15NC).
This panel sat in the middle of the head and it could be custom ordered with the user’s name engraved on it.
There are a few things to note about Ampeg production from this time.
Hey Zach, I’ve got an Ampeg B-15, serial number 0137XX, and I suspect it is from the mid 1960s.