[sdiy] Filter slopes

[Adam Inglis]

Yes, the term “coupled resonators” had me intrigued as well - sounds like a potentially powerful mechanism… Achim?

> On 12 Jun 2018, at 8:04 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> 
> Ok, I don’t know anything about “coupled resonators”. What would I look up to find out more (aside from that obvious term ), and how would I implement such a thing for analogue audio? Making “resonators” is easy enough. How do I “couple” them?
> 
> I’m looking for a practical implementation with details of how that was arrived at, rather than a highly abstract splurge of math that I won't understand and which could probably be explained in words of two syllables or less if anyone took the time to bother.
> 
> Thanks,
> Tom
> 
> ==================
>       Electric Druid
> Synth & Stompbox DIY
> ==================
> 
>> On 11 Jun 2018, at 20:50, ASSI <Stromeko at nexgo.de> wrote:
>> 
>> On Monday, June 11, 2018 7:43:22 AM CEST Elain Klopke wrote:
>>> I was reading an article about the spectral content of various instruments
>>> (woodwinds and strings) and while they didn't have any circuits, there were
>>> some tables showing cutoff frequencies and high and low slopes. Several of
>>> the pictures looked like bandpass filter responses with different slopes on
>>> each side. How would I go about doing that? Is the slope determined by the
>>> gain of the op amp in an active filter? If it's that easy, would it be a
>>> highpass filter followed by a lowpass filter each with their own gain
>>> settings?
>> 
>> Both woodwinds and string instruments (among others) can be modeled with 
>> coupled resonators.  The characteristic timbre of each is related to the modes 
>> of these resonators and the transfer of energy between them.  The slopes of 
>> the bandpass skirts depend on both the quality factor of the resonator and the 
>> coupling strength to other resonators or resonator modes.  Generally speaking, 
>> losing energy (e.g. into another mode) is a reduction in Q and hence shows up 
>> as a flattening of the slope.  If you just want to approximate the magnitude 
>> response, a filter bank with a high enough number of filter bands is as good 
>> as any other method and relatively easy to implement, it just uses many de-
>> coupled resonators instead of few(er) coupled ones.
>> 
>> 
>> Regards,
>> Achim.
>> -- 
>> +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+
>> 
>> Wavetables for the Terratec KOMPLEXER:
>> http://Synth.Stromeko.net/Downloads.html#KomplexerWaves
>> 
>> 
>> 
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