Invisible wrote:
>>> Of course, it's not quite the same. With electronics, you have to 
>>> remember that your "10 Ohm" resisters are actually 10 Ohm +/- 10%. ;-)
>>
>> Right, unless you have 1% resistors.
> 
> Even then, you have to be careful that your design won't malfunction 
> wildly if one of the two "identical" resistors isn't quite "identical", 
> for example.
> 
> With digital IIR, you just have to be careful about numerical stability.
> 

Real world is never as nice and neat as ideal..

> 
> Yeah, it's tricky. There are several possibly ways to map the s-domain 
> to the z-domain - including advanced techniques where one specific 
> frequency maps exactly while the rest are all approximate. (E.g., so you 
> end up with a correct cutoff frequency even if the rolloff angle is 
> different.)
> 

Hmmm. That I did not know...

> 
> Yeah, I think I have a picture somewhere on my harddrive of him doing 
> his "it's time to ****ing FEED ME!" expression. Except that, of course, 
> you can never tell if he means "feed me" or something else - just "I'M 
> NOT FRIGGIN HAPPY!"

He's in the point in a vague direction and grunt. If you don't figure 
out what he wants immediately, he goes thermonuclear on you. Quite fun. 
Just the tip of the terrible twos iceberg, I'm afraid.

> I just hope he doesn't grow up to be an idiot. Because, man, that would 
> be seriously upsetting as a parent, I imagine... o_O

Me, too. I can only hope our guidance through his early years will lead 
to him making sound decisions later in life.

Of course he has the option to ignore all of our guidance advice and 
upbringing, too. :/

>> I thought about downloading the demo to play around with.
> 
> What, Reaktor?
> 

Yes, They have a time-limited demo (with no saving ability) just to play 
with. I imagine I won't be able to do terribly much in 30 minutes ... 
but I can play for a bit.

> 
> The numerical stability depends on the exact kind of arithmetic you use. 
> (Integer, fixed-point, floating-point, single-precision, 
> double-precision, denormals...) A Chebyshev LP filter with high-order 
> basically involves turning the feedback path gain up higher and higher, 
> and the input gain lower and lower (to keep the passband at unit gain), 
> until the whole thing becomes completely unworkable.

Right. Eventually rounding error will add up causing instability.

> Still, I gather that with analogue electronics, anything much beyond 6 
> poles is basically hopeless...
> 

Hmmm, that would be a rather ugly circuit design, I imagine....

> 
> ...CLR is on more than one platform? :-P
> 

Look at mono.

> I've always loved synthesizers because... I like the crazy music they 
> make! :-D My dad has some old Moog recordings on LP. Obviously the 
> synthesizer itself is pretty lame, but some of the compositions people 
> put together... they don't make recordings like that any more.

Ooh, Moog.. neat :) Wish I could find some really good synth tracks.


>> Very much the IIR plucked string in the applet.
> 
> And then you get into the whole "waveguide synthesis" thing, like 
> Reaktor's Steampipe instrument. Very neat...

I remember you posting something created with Steampipe.

-- 
~Mike

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