Tom Carpenter at Analogue Solutions
(http://www.users.globalnet.co.uk/~concuss/) can mod your 606 heavily,
giving it alot more sonic depth than "just" the bassdrum mod.  Basically
he attaches a gray box to the back of your 606 which has 13 extra knobs
on it for playing with the sounds.  If you're an electronics whiz, you
can just order the kit from him and mod it yourself - this has the added
bonus of you trying desperately to fit the mods inside the 606 itself :)

Here are the details:


Box permanently attached via 2x16 way ribbons
box grey, black pots.

Box is 16x10x5 (cm WxDxH)
sloping front panel.

BD has tune and tone (tone is level of 'click' sound) - decay not possible
as the BD has no envelope

SD has tune, snappy, decay. when tune is set to max, oscillator becomes
inaudible, so you only hear the noise.

TOMS have sweep (envelope onto pitch) and tune each

CY has decay and tone (a filter cut-off - hipass)

HH has tone (a filter cut-off - hipass)

and CY & HH also share a 2nd tone (another filter cut-off - hipass)

Original sounds can be recreated.

Wide range of sounds available.

Options are separate audio outs, separate trigger outs (for each sound) and
trigger ins.
Maybe one day I'll add audio ins thru filter.

I also sell a rack mounting bracket.

All pics are on the web site.