[sdiy] Mood Ladder Filter: Many Questions!

[Tony Clark]

> You can add extra poles... until you run out of power supply voltage. 
> Someone made a five pole version.  As you add poles, the cutoff becomes 
> more abrupt (or should... if they track well).  Might not be as musical 
> as you might like.

   That would be me.  Mine is variable from 1 to 5 poles.  Sweeping the 
poles doesn't work as well as I would like it to, unfortunately, but 
otherwise, it is an extremely versatile filter.  Does about everything 
from Roland System 700 to Oberheim, and everything inbetween.
   As for getting other modes, about the only way I know of to do this is 
to do the subtraction trick.  Subtrack the LP output from the input to 
achieve something akin to an HP response.  I also did this, but it was 1) 
extremely hard to tune in 2) just doesn't really sound anything like a 
true HP filter.
   You _can_ do a HP moog filter, but it takes a _LOT_ of iron!  One of 
these days I'll build one of those...

   Cheers,

   Tony

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