Re: [sc-users] LowShelf/HighShelf

[crucial felix <felix@xxxxxxxxxxxxxxxxxxx>]

see these :

// Regalia-Mitra type filters
// coded by jl anderson - 13 mar 2002

eg:

RMShelf {

	*ar {
		arg in,			// input signal
			freq = 440.0,	// the corner freq
			k = 1.0;		// RM k factor

		var allpass;
		
		allpass = Allpass1.ar(in, freq, k.sign);

		^( 0.5 * (in + allpass + (k.abs * (in - allpass))))
	}
}


I did try and do SOS coefficients a long time ago but I could never 
figure out how to get from the 6 coefs in my texts to the 5 that we 
use.


On May 2, 2004, at 1:09 PM, newton armstrong wrote:

> i've been making some synthdefs for equalisation. MidEQ is great, but 
> it seems the LowShelf and HighShelf UGens are not finished yet. i 
> figure both of these could be implemented using FOS but i'm not sure 
> how to translate from a front-end like this: Synth("LowShelf", 
> [\cfreq, cfreq, \db, db]) to FOS coefficients. has anybody done 
> something like this already?
>
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-felix