Is anyone familiar with the Akai Unibass pedal? They no longer make it and it's ideal for a three piece band. It'd be way cool to have one of those cloned.
Found this: http://www.diystompboxes.com/smfforum/index.php?topic=32978.0
I can do it in digital, but I can't think of any way in analog -- especially the 5th's.