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Dynamically changing Delay Line

Jul 28 2010 | 9:09 pm


Does anyone know how to create a dynamically changing delay line using tap in tap out where it doesn’t distort the audio too much. I am trying to create continuous non-linearity in the string. Excuse me if I don’t have the terminology correct.



Jul 28 2010 | 9:27 pm

Are you modulating the delay line at audio rate? That’s the first step. The second would be to smooth the changes in the modulating signal with onepole~/slide~/rampsmooth~ etc… if necessary. This depends on how you’re modulating though, if you’re using an lfo (cycle~/phasor~ etc…) then a smoothing filter won’t be necessary.

I’m not well-versed in physical string modelling (sounds like what you’re doing), so I can’t offer much advice on exactly how to go about achieving the non-linearity that you want.

Jul 28 2010 | 9:40 pm

Nice one Tim. I’ll give that a try. What I have tried to do is modulate the delay length of a Karplus strong with a another Karplus Strong so that it kind of fades out and eventually stops changing the delay length but it’s still a bit glitchy. Cheers anyway!

Jul 28 2010 | 11:26 pm

I’m afraid modulating the delay line with the audio rate distorts it even more.I’m going to have to figure something else out. Thanks for your help anyway.

Jul 28 2010 | 11:50 pm

Could you post an example? You should be able to modulate tapout~ at audio rate with no glitches/distortions. Maybe you’re modulating so fast you’re creating FM sidebands, hard to say without seeing a patch.

-- Pasted Max Patch, click to expand. --

Jul 29 2010 | 9:04 am

tim is right as usual. in the meantime, the poletti m4l example is sitting in your patches folder and works great: Max5/patches/m4l-patches/Tools resources/M4L.vdelay~.maxpat

Jul 29 2010 | 1:17 pm

Nice one guys. The patch I have attached is part of a bigger patch. I’m trying to physically model a sitar as part of my masters thesis. All the main inner workings of my model are contained in the patch I have attached.

  1. string.maxpat
Jul 29 2010 | 1:20 pm

Actually might as well include the whole thing for clarity. At the moment I have it set to modulate the tapin tap out with not using the audio rate. Everything is in the string1 subpatch

Jul 29 2010 | 1:53 pm

I made some tiny changes that seem to have stopped the distortion, but I may be missing something; it’s a big patch! The bits I changed are outlined in red.

Jul 29 2010 | 3:41 pm

That’s perfect Tim!! Thank you so much, you’ve saved me many a panic attack. My thesis is due in a few weeks.

Sep 08 2010 | 9:45 pm

interested to hear the final thing did you do more to it?


Sep 15 2010 | 4:31 pm

I have indeed, submitted my thesis last week. Please find attached and enjoy.

Sep 15 2010 | 6:06 pm


Sep 15 2010 | 6:58 pm

great stuff.

you forgot to include the "sitar.mid" file?…

Sep 15 2010 | 7:01 pm

It’s not worth listening to really, very simple demo of its sound. Although, I did do a composition using it. Its not very obvious I used it though because of all the time stretching.

It’s called "Called Anon Tiro"

Sep 15 2010 | 7:02 pm

really good work, thanks for posting. Will you make the thesis available too?

it’s a shame that the tuning is compromised in the higher registers. A bit better with sigvs @ 4, but then the cpu goes through the roof.


Sep 15 2010 | 7:26 pm

I will indeed, I still have a week to make a few changes to the writing, I’ll post it when it is finished.

Ya the thing eats cpu big time, it’s a pity.

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