[sdiy] Other resonator designs

[Tom Wiltshire]

On 13 Aug 2009, at 14:09, Scott Nordlund wrote:

>
> Most instruments (including electric guitars, unless you're using  
> piezo bridge pickup) already have their own characteristic  
> formants, so you can only add to what coloration is already there.
>
> Of course synths will have a specific spectrum as well, according  
> to your choice of waveform, though this isn't a formant because it  
> changes with pitch.  The "pure" way to do it (formant synthesis)  
> uses an impulse train as input, in which case the harmonic content  
> is determined entirely by the filtering.


This is exactly the sort of stuff that I'm getting excited about. The  
oscillator section of a synth is equivalent to (say) the strings of a  
guitar or 'cello. This basic sound is then heavily coloured by the  
formants caused by body and cavity resonances. This gives the overall  
'tone' of the instrument.

Having one filter that follows the pitch of the note is much more  
equivalent to altering the type of string that you're using, rather  
than any kind of body modelling. This is one reason subtractive  
synths don't sound at all naturalistic. And that's before you go  
"Beeeooowwwwmmm!" with your envelope and blow any chance of realism!

Personally, I'm not particularly fussy about pure formant synthesis.  
It seems reasonable to me to have a complex system generating the  
sound that gets 'processed' by the body. After all, a piano mechanism  
isn't exactly straightforward, even before we get into the details of  
formant filtering caused by the soundboard and whatever other  
resonances there are. Secondly, (and again very personally) I'm  
mostly interested in abstract sound synthesis, so I'm not attempting  
to design a synth that sounds exactly like a 'cello. However, I would  
like to design a synth that has the *depth* and *richness* of a  
cello's tone, and I suspect that body modelling is quite a big part  
of that. Adding an artificial body model consisting of a number of  
resonances (and notches too, don't forget them) seems to offer  
another layer of depth to synthetic sound.

A big positive to all resonators from me.

T.