[sdiy] Pole Mixing

Richie Burnett rburnett at richieburnett.co.uk
Fri Apr 9 10:46:31 CEST 2021

Fantastic piece of work!

I like how you can choose the most useful "preset" combinations from the 
drop down menu and it sets the mixing coefficients for you, and shows the 
Laplace transfer function.

It's great how you can move the sliders to alter the mixing coefficients and 
watch how it alters the resulting frequency response.  A very graphic 
indication of how the tolerance on the pole mixing coefficients is important 
to get good stopband attenuation in some of the filter modes.

Thanks for sharing David.


-----Original Message----- 
From: David Moylan via Synth-diy
Sent: Thursday, April 8, 2021 11:24 PM
To: synth-diy at synth-diy org
Subject: [sdiy] Pole Mixing

Hi All.  I banged together a little web app to play around with filter
pole mixing, of the Oberheim Xpander type.  You can mix poles in varying
amounts and see the output magnitude shape as well as the transfer
function.  Y axis is Db and X axis is log scale based on normalized
frequency (so basically 1 equals the cutoff frequency).  Haven't done
phase plot yet.

If you have an interest in this sort of thing check it out:



David Moylan
Expedition Electronics
sonic adventures!

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