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. best, Casper On Thu, Oct 12, 2017 at 9:06 AM, Casper Schipper wrote:

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 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

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

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