[sdiy] Non-linear synthesis

[labolida]

Hi Tom

I haven't enough experience with digital synthesis too.
I think the dsPIC30F4013 is a good choice altough 
the small memories and speed limitations.

I haven't experience with waveshapers or phase 
distortion and my experience is with fixed waveforms.

I have just put the source code in 
http://www.sdiy.org/labolida/ and I hope help you
with any ideas.

I have used the Microchip C30 compiler student 
edition with the MPLAB, both free.

Good luck for you in the digital world..!

Miguel
---------- Cabeçalho original -----------

De: synth-diy-bounces at dropmix.xs4all.nl
Para: "synth-diy DIY" synth-diy at dropmix.xs4all.nl
Cópia: 
Data: Thu, 26 Jul 2007 22:26:46 +0100
Assunto: [sdiy] Non-linear synthesis

> Hello all,
> 
> I've recently started learning about digital synthesis. I have to  
> admit that for years I've been an analogue-only kind of guy, and that  
> I rather looked down my nose at digital synths. Probably a result of  
> being a teenager in the 80's - digital synths really did sound awful  
> back then. However, technology has moved on, and Antti  Huovilainen  
> showed that you can even do a decent Moog filter digitally these days  
> - something I'd never have thought possible. (http:// 
> dafx04.na.infn.it/WebProc/Proc/P_061.pdf)
> 
> However, I'm starting simple, and playing with the dsPIC 30F4013 16- 
> bit processor. The main limitation is the very limited memory for  
> wavetables (16K), although time is always an issue too.
> 
> I've got three stages in my current digital oscillator design. It has  
> a basic DDS oscillator, to which phase distortion (PD) is applied,  
> under voltage control. The output from the PD oscillator is then  
> passed through a waveshaper function, also under voltage control.  
> This effectively lets me modify both the X and Y axes of my sound  
> wave using arbitrary functions. Feeding envelopes or LFOs to these  
> two CV inputs is good fun.
> 
> The PD stage seems pretty versatile. It'll produce some crazy filter- 
> esque sweeps and squorks. However, PD is equivalent to FM limited to  
> only integer ratios, so there are very closely related techniques  
> that are much _more_ versatile. That said, FM has a definite sound.  
> PD seems to do a lot of "Parp" and "Burp" noises suitable for brass  
> perhaps, but doesn't really push the outer edges of the synthesis  
> universe, which is where I want to be!
> 
> The waveshaper stage is singularly unexciting. I was expecting much  
> more. Granted, I've only got four functions in it, but a couple of  
> them are quite complex, with loops and bends like a Serge middle  
> section. In fact, the function that sounds best is a soft-knee  
> distortion, which produces a nice crunchy attack on notes when you  
> feed an envelope to the control voltage input.
> 
> Does anyone have any experience with waveshapers or phase distortion  
> synthesis to share? Any good waveshaper functions? Anything I should  
> avoid? Any other non-linear synthesis techniques I need to know about  
> or try? Things to investigate? Ideas?
> 
> I'll put some details of the project online at some point when it  
> solidifies a bit more. At the moment it's still at the "breadboard  
> spaghetti" stage.
> 
> Regards,
> Tom
> 
> 
> 
> 
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