Hello Csounders, I was reading about reverberation in differents sources and
using playing with examples in the  FLOSS-Manual
<http://write.flossmanuals.net/csound/e-reverberation/>   and I would like
to more about "The Schroeder Reverb Design".

What this means is:

- How the alpass opcodes work? I read about it  here
<http://www.csounds.com/manual/html/alpass.html>   and I couldn't understand
the difference between the xrvt and ilpt parameters.
What is the difference between the reverberation time and loop time?
Does this opcode change the phase of the signal?

- The comb filter opcode is treated as reverb opcode instead of a filter (or
maybe is the same), that somehow makes me confuse.

- What is the difference, in a practical way, between comb and alpass
opcodes? (When you are designing a reverb)


Basically, I would like to have an intuitive understanding of these things
to be able to make my own reverberation systems from scratch.

Any suggestions/help are more than welcome.
Thank you in advance.






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Hi,

It is an interesting topic, and it is not uncommon that there is some confusion of terms around different filters.

In general terms in DSP, a filter is a process that modify the signal in any way. It does not have to subtract from the signal, it can also add, or do other modification. In this way, a reverb is also a filter. A single allpass of comb filter makes a shitty reverb, but still, we can talk about decay time (reverberation time), as it has a decaying tail of "echoes".

There is a basic introduction here:

http://gdsp.hf.ntnu.no/lessons/6/  

Some more here

https://ccrma.stanford.edu/~jos/pasp/Allpass_Two_Combs.html 

and the  whole chapter there really

https://ccrma.stanford.edu/~jos/pasp/Acoustic_Modeling_Digital_Delay.html 

Also, the Springer Csound book has a nice section on time domain processing, where comb and allpass filters are explained well.

all best

Oeyvind 

ons. 25. des. 2019 kl. 12:23 skrev slobodanip <slobodanip@gmail.com>:

Hello Csounders, I was reading about reverberation in differents sources and
using playing with examples in the  FLOSS-Manual
<http://write.flossmanuals.net/csound/e-reverberation/>   and I would like
to more about "The Schroeder Reverb Design".

What this means is:

- How the alpass opcodes work? I read about it  here
<http://www.csounds.com/manual/html/alpass.html>   and I couldn't understand
the difference between the xrvt and ilpt parameters.
What is the difference between the reverberation time and loop time?
Does this opcode change the phase of the signal?

- The comb filter opcode is treated as reverb opcode instead of a filter (or
maybe is the same), that somehow makes me confuse.

- What is the difference, in a practical way, between comb and alpass
opcodes? (When you are designing a reverb)


Basically, I would like to have an intuitive understanding of these things
to be able to make my own reverberation systems from scratch.

Any suggestions/help are more than welcome.
Thank you in advance.






--
Sent from: http://csound.1045644.n5.nabble.com/Csound-General-f1093014.html

Csound mailing list
Csound@listserv.heanet.ie
https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
Send bugs reports to
        https://github.com/csound/csound/issues
Discussions of bugs and features can be posted here

Csound mailing list Csound@listserv.heanet.ie https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports to https://github.com/csound/csound/issues Discussions of bugs and features can be posted here