Preamp in Chaparral Bass

[jknorton]

 I fairly recently acquired a '92 Chaparral 5-string bass. Iridescent sparkle finish, set neck. It has factory (as far as I can tell) Bartolini pickups. Wired as  Volume, Tone, Tone with three way switch. Does anyone recognize this preamp? Is it Hamer, or Bartolini, or perhaps something else? The tone controls seem to have  a rather subtle effect, does anyone know if they would be Bass/treble, or perhaps Mid/Treble.?  Thanks - John K.

[serial]

Here's the Hamer Bass w/BTS circuit:

 

[HAMERMAN]

My first thought would have been Bartolini but I think they are always potted into the plastic tubs with a prominent Bartolini label on top and their wires are discrete - not part of a ribbon cable like here. It's also pretty unusual for a board to be partially potted like that allowing you to change Op-amps like that. 

[jknorton]

Thanks for the responses so far. The ribbon cable, dense layout would seem to indicate some rather mature design. I have Bartolini preamps in some other basses - none look similar - although I haven't taken the obvious step of asking them directly - I'll do that tomorrow.