[chuck-users] what exactly is tuned feedback?

Casper Schipper casper.schipper at gmail.com
Thu Oct 12 12:09:06 EDT 2017

And indeed: the correct answer to your question you already provided
yourself. :-)
The pitch is achieved by making the delay one wavelength long:
second / frequency  => del.delay;
Sometimes however, introducing a (resonant) filter changes the tuning a
bit, so then you need to tune more on ear.


On Thu, Oct 12, 2017 at 9:06 AM, Casper Schipper <casper.schipper at gmail.com>

> Dear Michael,
> From the description it looks like a feedback delay (= comb filter) with
> another (lowpass) filter in the loop. This type of feedback network can be
> used like a basic (perhaps even simplistic) physical model of vibrating
> objects like strings, collumns of air in tubes etc. The general term is
> waveguide synthesis.  A feedback loop with a lowpass in the feedback is
> often used to produce plucked string like sounds.  Karplus-Strong synthesis
> is the original name for one particular efficient implementation of it
> (using a simple 2 sample averaging as the lowpass filter, and filling the
> delay line with noise at the start). You can also have really nice affects
> adding some distortion or wave shaping in the loop (x - x^3 etc..). Chuck
> is a really great language for building these things, since you can easily
> write your own filters and shapers using Chugen, or Fauck (Faust for
> chuck). But Faust takes a little more reading to understand in my opinion.
> If your interested to dive deeper, there is an excellent online book by
> Julius O Smith III, which starts with very simple models and goes into very
> detailed models of a lot instruments (reeds, drums, flutes etc). His work
> also formed the basis of some of the STK Ugens in ChucK:
> https://ccrma.stanford.edu/~jos/pmupd/Strings.html
> best,
> Casper
> On Wed, Oct 11, 2017 at 10:22 PM, Michael Heuer <heuermh at gmail.com> wrote:
>> All,
>> The Dave Smith DSM03 Feedback module has what is described as tuned
>> feedback
>> https://www.davesmithinstruments.com/product/dsm03-feedback-module/
>> I have the same question as was posted here
>> "I'm trying to understand what 'tuned feedback' means -- does this mean
>> the signal enters a delay line that lasts one cycle of a certain pitch?
>> (So, say, a 50Hz sound is a 20ms delay line.) Does this end up reinforcing
>> that pitch when you hear the sound? (I guess it would reinforce multiples
>> of the pitch too, but less so.)"
>> https://www.kvraudio.com/forum/viewtopic.php?p=1673572&sid=a
>> e6a060ebaffea267114c1b6b5edde68#p1673572
>> Thanks!
>>    michael
>> _______________________________________________
>> chuck-users mailing list
>> chuck-users at lists.cs.princeton.edu
>> https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
> --
> Casper Schipper
> casper.schipper at gmail.com
> +31 6 52 322 590

Casper Schipper
casper.schipper at gmail.com
+31 6 52 322 590
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