[PD] Pre Loading a Delay Line

[padawan12 at obiwannabe.co.uk]

>Hallo,
>Michael Garrett hat gesagt: // Michael Garrett wrote:
>
>> Here is a link to the simple synth I am starting with. It simulates the
>> sound of a PVC type xylophone. It adjusts the delay length based on the
>> requested note.
>> 
>> It is this synth that got me thinking about pre-exiting the delay line
>> in order to get low frequency sounds.
>> 
>> http://www.garrett-technologies.com/Music/pvc_synth.zip
>
>You synth sounds very nice! A little hint: You can use $0 in the name
>of delay lines instead of $1. That way you could get rid of the A, B,
>C, ... stuff that you use to differentiate between delays. As all your
>delays are in a seperate abstraction $0 will be unique. 
>

Yeah, great resonator sound. It makes some nice basses in the lowest 
registers. You could optimise by using a [bp~] insetad of a [vcf~] in the waveguide, because you aren't moving the center frequency, and I think [block~ 1] is possibly overkill, you should get away with a much bigger blocksize, that makes the voices more CPU hungry. 


>Then I don't really understand why preloading the delay line should
>give better low frequency sounds. Is it, because with lower notes and
>thus longer delay times you will have to wait longer for the first
>result? Isn't that the same with a real double bass, which also has a
>certain inertia?

Yes, but that wouldn't be appropriate for a xylophone. I think it depends on the excitation mode and what instrument you're modelling whether to pass the excitation impulse directly through (or through a body formant), or only take it from the "cold" side of the delay where it's one period late. I think this is how you decide.. If it's a displacement that you're modelling, like plucking a bass string at the middle (antinode) then yes you want to have the delay, that's the time until you really hear anything from the moment the pick is released, the time to propagate along the string. But for struck instruments, the hammer excites the whole thing locally, and the waves spread out and travel back and forth until they fall into phase with the waveguide (delay), (Karplus-Strong), and then you want to hear the delay contents as quickly as you can, so you want the buffer to be preloaded with an image of the impulse. 

Are you doing that here? How do you do it, I cant see it? Is that why you set the blocksize so low? 

a.


>You have some minor bugs in your patch: First the [poly] number "4" is
>too small to get all possible polyphony. You could raise it to 8. Then
>you should check the triggering in pcv_synth_001.pd: You have to make
>sure, that the [1000( gets sent to the [/ ] after the [mtof] was send
>there. This isn't sure in your patch. Attached is a version with a fix
>that involves creating an additional outlet for the trigger-object.
>
>Ciao
>-- 
> Frank Barknecht                 _ ______footils.org_ __goto10.org__
>
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