> From: w.boeke@upcmail.nl
> To: linux-audio-dev@lists.linuxaudio.org
> Subject: Re: [LAD] Software sound
>
> Hi Nick,
> Sounds interesting, but also rather vague.

Vague? Yeah, I could go along with that. The thing is, how do you describe a sound quality in words? I have heard people compare filter variants as 'fruitier' or 'squelchier' than others.

Whatever words do it for you, take them. The alternative is not that difficult: rig up a synth that can select between Chamberlain and other filter algorithms and listen to them. They all have really different qualities and personally I don't think it is as simple as adding sub-harmonics.

> If the differences between Moog and Chamberlin are subtle, then Moog isn't worth its extra CPU cycles.

Again, you have to decide that for yourself, I would definitely rate Fons' and Huovillainen's algorithms as more than worth the extra CPU but I accept that it is subjective. There are plenty of cases where using a Chamberlain in a synth that is buried in the mix will hide its deficiencies. Use it as a solo/lead instrument and it will be lacking.

> 'Warmth' depends on the lower harmonics. If you are aiming for warmth then start with a base signal with more lower harmonics, e.g. a square wave i.s.o. a pulse. Also equalizing and a suitable
> amplifier are important. And the ultimate way to get warmth is to add a small amount of 1/2 or 2/3 harmonics. In software this is easy, for real instruments it's impossible!

I don't think this really works, it is akin to just lowering the input signals by some given divisor. It does not address the non-linear aspects of the filter and it does not address how the irregularities of the filter change over the cut-off range whilst it is being driven by a modulation signal (env/pressure/etc) - these are both aspects of the above algorithms that are not addressed by Chamberlain filters.

Can't help you with your questions on input signals, frequencies, etc. I don't have them and I refer back to describing a sound as to whether these parameters are relevant. I used to be a musician playing in bands, then later started writing software. A few years down the line I used to records stuff, look/edit the sampled waves and got to the point where I would think 'man, you have to come and look at this sound!'

At that point I gave up on being a musician. When I stopped getting my ears around the sound then making music lost much of its charm.....

Nick