Stop the presses, I showed this pickup to Mr. Bartolini and he said that it's actually a
guitar polyphonic as the six bars on the cover indicate the optimum string spacing, not a bass
pickup as I assumed by the writing on the bottom. He also said the "bass" written on the
bottom was not his handwriting.
OK, they stopped making HI-A pickups in 1978. Bill Bartolini reorganized and continued
making his fabulous pickups with the Bartolini name on the pickup. Here's an example of an
early HI-A polyphonic pickup. Each coil is accessible through a pair of wires shown below in
the Bottom View picture. In the configuration shown, the coils have been summed and the
signal output is on the blue wire (#1), the signal Ground is the black wire (#2) and the shield
is the other black wire (#3). Unfortunately, I can't tell you which wire pair is for which coil.
This is a medium power and bright pickup intended as a humbucker replacement with the string
spacing shown in the picture above. It has a DCR of 4.5Kohm.