http://cgi.ebay.com/ALEMBIC-EPIC-BASS-5-String-Guitar_W0QQitemZ7403837154QQcategoryZ4713QQssPageNameZWD1VQQrdZ1QQcmdZViewItem
With an upgrade. Filter/Q?
I don't know anything about the bass. I'm just passing on the listing as a courtesy.
The listing says the controls are volume, pan, bass and treble. But I see what you mean, one of them looks like a switch. Or maybe it is a pot with a missing knob? I don't know, you would have to ask the seller.
Curt
It looks like it has Essence electronics and Q-switch. This would be an upgrade from the standard electronics.
Keith