[Fpga-synth] Physical Model Experiments

[Eric Brombaugh]

Agree. Either scale you excitation to prevent overflow, expand the range 
of your datapath, or add clipping/saturation. From your description it 
sounds like you've actually got overflow/wrapping which will really 
sound harsh.

Hard clipping is simple to do (I think I sent an example a while back) 
and will be a big improvement compared to overflowing. Soft clipping is 
fairly complex to implement - it requires either lots of math, or else 
lookup tables. If you have the time and resources to do it though it 
would be interesting to compare the various approaches.

One of things I've noticed about the instrument biz is that what may 
seem like a problem is often turned around and used to advantage. 
Distortion that would be unacceptable in a traditional signal processing 
system may be just the thing a musician is looking for. Providing 
options is a great way to expand the useful range of an instrument.

Eric

JH. wrote:
> 
> IMO, what you need to do, is find a way for this to happen pleasantly, to go 
> into distortion smoothly, to create a palette of sounds that are different 
> depending on your new excitation (velocity etc.), *and* the previous state. 
> 
> ----- Original Message ----- 
> From: "Scott Gravenhorst" <music.maker at gte.net>
> 
> The main problem is that if I excite the waveguide with a full scale pulse,
> it vibrates nicely and sounds good/useful.  But if I excite the string with
> a full scale pulse again while the string is still vibrating, I get varying
> degrees of distortion due to clipping/sign reversal.  I do understand why
> this is happening, but I need to figure out how to stop it from happening.