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Karlsen Fast Ladder
Type : 4 pole ladder emulation
References : Posted by arifovekarlsen[AT]hotmail[DOT]com
Notes :
ATTN Admin: You should remove the old version named "Karlsen" on your website, and rather include this one instead.
Code :
// An updated version of "Karlsen 24dB Filter"
// This time, the fastest incarnation possible.
// The very best greetings, Arif Ove Karlsen.
// arifovekarlsen->hotmail.com
b_rscl = b_buf4; if (b_rscl > 1) {b_rscl = 1;}
b_in = (-b_rscl * b_rez) + b_in;
b_buf1 = ((-b_buf1 + b_in1) * b_cut) + b_buf1;
b_buf2 = ((-b_buf2 + b_buf1) * b_cut) + b_buf2;
b_buf3 = ((-b_buf3 + b_buf2) * b_cut) + b_buf3;
b_buf4 = ((-b_buf4 + b_buf3) * b_cut) + b_buf4;
b_lpout = b_buf4; |
Comments
Added on : 08/01/07 by nobody[ AT ]nowhere[ DOT ]com
Comment :
Where are the coefficients? How do I set the cutoff frequency?
Added on : 09/01/07 by scoofy[ AT ]inf[ DOT ]elte[ DOT ]hu
Comment :
The parameters are:
b_cut - cutoff freq
b_rez - resonance
b_in1 - input
Cutoff is normalized frequency in rads (2*pi*cutoff/samplerate). Stability limit for b_cut is around 0.7-0.8.
There's a typo, the input is sometimes b_in, sometimes b_in1. Anyways why do you use a b_ prefix for all your variables? Wouldn't it be more easy to read like this:
resoclip = buf4; if (resoclip > 1) resoclip = 1;
in = in - (resoclip * res);
buf1 = ((in - buf1) * cut) + buf1;
buf2 = ((buf1 - buf2) * cut) + buf2;
buf3 = ((buf2 - buf3) * cut) + buf3;
buf4 = ((buf3 - buf4) * cut) + buf4;
lpout = buf4;
Also note that asymmetrical clipping gives you DC offset (at least that's what I get), so symmetrical clipping is better (and gives a much smoother sound).
-- peter schoffhauzer
Added on : 26/06/07 by arif[ AT ]str8dsp[ DOT ]com
Comment :
Tee b_prefix is simply a procedure I began using when I started programming C. Influenced by the BEOS operating system. However it seemed to also make my code more readable, atleast to me. So I started using various prefixes for various things, making the variables easily reckognizable. Peter, everyone, I am now reachable on www.str8dsp.com - Do also check out the plugin offers there!
Added on : 17/07/07 by aok[ AT ]str8dsp[ DOT ]com
Comment :
Here's even another filter, I will probably never get around to making any product with this one so here it is, pseudo-vintage diode ladder.
Diode Ladder, (unbuffered)
// limit resonance, rzl, tweak smearing with fltw, 0.3230 seems to be a good vintage sound.
in = in - rzl;
in = in + ((-in +kbuf1) * cutoff);
kbuf1 = in + ((-in + kbuf1) * fltw);
in = in + ((-in +kbuf2) * cutoff);
kbuf2 = in + ((-in + kbuf2) * fltw);
etc..
Added on : 09/09/07 by dev[ AT ]fxpointaudio[ DOT ]com
Comment :
"Cutoff is normalized frequency in rads (2*pi*cutoff/samplerate):
This seems to be valid for very low ( < 200 Hz ) frequencies - higher sample rates seem to be "Closer"
thanks
Added on : 17/07/10 by checkpageforemail[ AT ]checkpageforemail[ DOT ]com
Comment :
I also did a 9th order gaussian filter (minimal phase), using only 5 orders, for my limiter, which is released under the GPL LICENCE. http://www.paradoxuncreated.com
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