[sdiy] can i make a filter cutoff pedal for my Prophet 600?

[Tom Wiltshire]

Dan,

> I have heard from a few people that you can get a much smoother  
> (non-stepped) cutoff sweep out of the prophet 600 if you use a  
> pedal to control the value.

Looking at schematics, you definitely do get a smooth analogue sweep.  
The filter CV input goes to half a CEM3360 VCA and then directly to  
the voices' filter cutoff CV inputs (on each voice's CEM3372 filter/ 
VCA chip).

> However i am not sure what standards the cutoff frequency jack is  
> looking for or  what sort of pedal i would need. could i just use a  
> voltage divider pot setup?

Yes, a simple voltage divider would do it. The user manual says the  
Filter CV input accepts a 0-10V CV input.  You could use a 9V battery  
across your pot and bingo!

> it would be cool to be able to input CV signals from something like  
> the wogglebug as well.
> but i dont want to mess up my prophet.

As long as the wogglebug doesn't bang out a lot more than 10V, it  
should be fine.

Regards,
Tom