[sdiy] continuously variable swing

[gregory zifcak]

hi,
i've recently been obsessing about the idea of having a pot on my 707 to 
vary the swing from negative values through zero to positive. it seems like 
it might not be too difficult to replace the tempo oscillator in the 707 as 
it's separate from the cpu, however i'm not quite sure how to implement the 
swing. basically what i want is to be able to shift every other 16th note 
from early to late. i've heard that the korg kr-55 and roland cr-8000 have a 
variable positive swing control, does anyone know how this is achieved, or 
where i could find the schematics?
thanks for any suggestions,
greg