Both Classic Bass and Original Bass are passive bass pickups that are cast in epoxy to eliminate microphonics. 

Classic Bass (CB) series bass pickups are designed for extended frequency range with higher resonant peaks.  Classic Bass therefore has more treble response to more completely capture the natural voice of the instrument. They capture more definition without sacrificing lows and low mids, so they provide excellent note articulation.

Original Bass series bass pickups are designed to enhance the deep tones with strong lows and low-mids with reduced treble response.  Original Bass pickups have a warmer, more vintage voice without being muddy, woofy or boomy.