[sdiy] Pole Mixing

David G Dixon dixon at mail.ubc.ca
Sat Apr 10 08:13:33 CEST 2021

I did more or less the same thing more than 10 years ago, but in Excel.  In
that case, the gain factor of the ABCDE are specified as integer values, and
the resonance is altered with a slider.  I found this very useful for
finding interesting modes, particularly with the various notches (including
the famous double-notch mode, which has the gain factors of 1-4-12-16-8).
The gain factors translate directly into resistor values for pole mixing.
This was the basis of the Intellijel Polaris.

I'd be happy to send the spreadsheet to anybody who wants it.

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of David
Moylan via Synth-diy
Sent: Thursday, April 08, 2021 3:25 PM
To: synth-diy at synth-diy org
Subject: [sdiy] Pole Mixing

[CAUTION: Non-UBC Email]

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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