[sdiy] HP from LP ?

[Gordonjcp]

On Tue, Aug 01, 2017 at 12:10:48AM +0000, Sean Ellis wrote:
> I have seen a way to inject the signal into the ladder to get a highpass response, Tom Gamble was the first person I saw do this but I cant find the original message (was on SDIY sometime around 2000). I have gotten highpass from the 303 filter in the same way:
> 
> https://soundcloud.com/tensiontype/303-highpass1
> 

Well hang on, how does it work in the Sallen-Key topology like in the
Steiner Synthacon?  I know that's not a ladder - it looks like one
opened out flat to balance the diode chain, but it's fed differently -
but there must be some way to do it.

The neat thing about that is it has both lowpass and highpass *inputs*
so it can act like a kind of frequency crossfader:

http://gjcp.net/mp3s/hilow.ogg

-- 
Gordonjcp MM0YEQ