[sdiy] Fixed Filter Bank demo

[brianw]

If there is a collection of Impulse Response files for various acoustic instrument bodies, then a frequency analysis of the body IR would give clues for the strongest resonances. Of course, obtaining the impulse response for an instrument body (independent of the strings or reed or other usual input) is probably quite challenging, and I am not currently aware of any such database.

Another source might be schematics for those old preset organs that have selector switches for various - usually orchestral - instruments. If they document the schematic thoroughly, then the frequencies and resonances should be apparent. I assume that these would all be fairly coarse, at least due to tolerances on passive components, but surely they’re accurate enough for those old synths.

I wrote an AudioUnit plugin that offers the set of filters and controls of a Polymoog Resonator (but it’s ‘ancient' - only 32-bit), so I am also interested in sets of up to three resonant frequencies that would suggest real instruments because these could be added to the plugin as factory presets.

Brian Willoughby


On May 23, 2022, at 4:34 PM, Ian Fritz wrote:
> Tim —
> 
> I’ve been working on this a bit. I’ve ported my 36 stage hardware filter bank into Reaktor and am using it with my Reaktor ensemble “Winsynth”.
> 
> Surprisingly, there doesn’t seem to be a table anywhere to give a lot of information. I have a textbook that gives coarse data for a few instruments, and a small table taken from a German text.  I seem to remember another old source but cannot chase it down.
> 
> Anyone else?
> 
> Ian
> 
> On May 23, 2022, at 3:05 PM, Tim Parkhurst wrote:
>> Nicely done!
>> 
>> Question: is there some sort of chart or reference guide to mimicking the resonant peaks and valleys of various acoustic instruments? Just going by ear could take forever (or lead down many blind alleys), so some sort of guide for filter banks or EQs would be extremely helpful. A similar guide for the Polymoog Resonator would also be a valuable resource. (Note: I think the Cherry Audio Polymode lets you route other audio in your computer through the Resonator, so that could be fun for those who don’t have the actual hardware)
>> 
>> Tim (resonant peak geek) Servo 
>> 
>> On Mon, May 23, 2022 at 9:36 AM Ingo Debus via Synth-diy <synth-diy at synth-diy.org> wrote:
>>> Hi,
>>> 
>>> here’s another short demo, this time of the Fixed Filter Bank I built 12 years ago.
>>> https://youtu.be/feo7DB85SBA
>>> 
>>> Anyone remember my Fischertechnik coil winding machine?🥸
>>> 
>>> Ingo