[PD] Help with reverb design and vanilla's abstractions ([rev1~]/[rev2~]/[rev3~])

Alexandre Torres Porres porres at gmail.com
Tue Mar 12 07:30:09 CET 2019

thanks everyone for all the "reverberation"

Em qui, 7 de fev de 2019 às 09:23, Dario Sanfilippo <
sanfilippo.dario at gmail.com> escreveu:

> as far as I understand, the idea is to have an FDN, with whatever matrix
> you've chosen, whose impulse response is as close as possible to white
> noise. The filters that you put inside the network can then be used to
> model different environments.
cool, thanks

There is an algorithm on the website of J. O. Smith to calculate the best
> approximation for a desired size while keeping the coprime relationship
> between the lengths:
> https://ccrma.stanford.edu/~jos/pasp/Prime_Power_Delay_Line_Lengths.html.


>  My reverb in PD is a 16th order FDN with Hadamard matrix and 1pole
> lowpass filters to model the absorption of high frequencies

yeah, I saw that on the facebook group, and also that you mentioned there
it was based on a model by "Rocchesso".

> I found these good reads:
> Rocchesso, D. 1997. “Maximally diffusive yet efficient feedback delay
> networks for artificial reverberation.” In Signal Processing Letters,
> IEEE 4 (9), 252­255.
> Rocchesso, D., and J. O. Smith. 1997. “Circulant and Elliptic Feedback
> Delay Networks for Artificial Reverberation.” I EEE Transactions on
> Speech and Audio Processing 5 (1):51–63.
yup, that's the source then :)  I was able to find them both online!

Now, a question. You say it uses a Hadamard matrix, but I've realized it's
basically the same matrix as used in [rev3~], it's only flipped vertically
(I hope you know what I mean) and I ask if it is the same matrix or if this
difference grants it to be another matrix that goes by a different name?

> Ciao,
> Dario

Tchau, obrigado
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