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[Csnd] Quadraphonic reverb

Date2026-06-02 14:39
From"Jeanette C." <000015cdd0ffa6cd-dmarc-request@LISTSERV.HEANET.IE>
Subject[Csnd] Quadraphonic reverb
Hey hey,
I'm currently working on something with a quadraphonic setup and I wondered if 
some of you had practical approahces to reverb.

I'd like to use reverbsc. How do you deal with that? Just use two reverbsc 
with the same setting? Slightly different settings or...

I'd appreciate any practical tips from you quadraphonic desperados. :)

Best wishes and thanks,

Jeanette

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Date2026-06-03 14:54
FromOeyvind Brandtsegg
SubjectRe: [Csnd] Quadraphonic reverb
Attachmentsscreverb_crush.csd  
Hi

Yes, screverb is a good candidate to build a multichannel reverb, but it is easier of you use the code version (the original Sean Costello code that led to the implementation of the screverb opcode). In the Csound code version, you have access to the separate delay lines, and can route them individually. As it uses 8 delay lines for stereo, you can duplicate it as needed (say, 8 delay lines per 2 speakers) and then send a few of the delay lines from one 8-line module as input to the next and thus daisy chain the reverb modules together.

F.ex:
Reverb 1 for output 1,2 uses delay line 1 to 8, feeding back to themselves
Reverb 2 for output 3,4 uses delay line 9 to 16, feeding back to themselves
Then route delay line 1,3,5 feed to the input of  Reverb 2, and route delay lines 10,12,14,16 feed to the input of Reverb 1.

It makes even more sense if you have even more output channels. I do have an 11-channel version of this somewhere on a backup.
For now, I just found the stereo version of the reverb in Csound code (attached). You can take it apart and invent your own configuration extension and routing, thinking of how parts of the reflections from one side of the room feeds into the late reverberation of the other part of the room.

Øyvind

tir. 2. juni 2026 kl. 15:39 skrev Jeanette C. <000015cdd0ffa6cd-dmarc-request@listserv.heanet.ie>:
Hey hey,
I'm currently working on something with a quadraphonic setup and I wondered if
some of you had practical approahces to reverb.

I'd like to use reverbsc. How do you deal with that? Just use two reverbsc
with the same setting? Slightly different settings or...

I'd appreciate any practical tips from you quadraphonic desperados. :)

Best wishes and thanks,

Jeanette

--
  * PeerTube: https://makertube.net/@jeanette_c
  * GitHub: https://github.com/jeanette-c
  * Youtube: https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g

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Date2026-06-03 15:08
From"Jeanette C." <000015cdd0ffa6cd-dmarc-request@LISTSERV.HEANET.IE>
SubjectRe: [Csnd] Quadraphonic reverb
Hi Øyvind,
many thanks for this suggestion and the way to work it. I will definitely give 
this a try. It sounds promising. There is one question though: when I set up 
additional delay lines for the other two channels, should the delays have the 
same length or should I vary the initial times slightly to avoid 
comb-filtering effects? This part of reverb setup has always really foxed me. 
:)

Best wishes,

Jeanette

--
  * PeerTube: https://makertube.net/@jeanette_c
  * GitHub: https://github.com/jeanette-c
  * Youtube: https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g

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Date2026-06-03 15:23
FromOeyvind Brandtsegg
SubjectRe: [Csnd] Quadraphonic reverb
You can use other prime number delay lengths for the extra delay lines.
It can seem like you have to be very careful about the delay lengths, but also remember that the delay times are modulated by ifs, and as long as the lfos are out of sync with each other, you are less likely to hit harmonic relationships between the delay lines. You will occasionally pass through a harmonic relationship between single pairs of delays, but it will not build as they are being modulated.
A simple solution is to do what is done in the freeverb algorithm, where each stereo channel has a 1 sample delay time offset in relation to the other. This gives some decorrelation between channels. Or find other delay times in the approximate same range. Just trust your ears, if it sounds good it should be ok. If you want to stress test the inharmonicity, run a short white noise burst into the reverb. That should trigger any ugliness lurking in there ;-)

Øyvind

ons. 3. juni 2026 kl. 16:08 skrev Jeanette C. <000015cdd0ffa6cd-dmarc-request@listserv.heanet.ie>:
Hi Øyvind,
many thanks for this suggestion and the way to work it. I will definitely give
this a try. It sounds promising. There is one question though: when I set up
additional delay lines for the other two channels, should the delays have the
same length or should I vary the initial times slightly to avoid
comb-filtering effects? This part of reverb setup has always really foxed me.
:)

Best wishes,

Jeanette

--
  * PeerTube: https://makertube.net/@jeanette_c
  * GitHub: https://github.com/jeanette-c
  * Youtube: https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g

Csound mailing list
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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