million dollar scientific EQ ? [Thread from 2007 bumped]
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- KVRAF
- 4908 posts since 10 Aug, 2004 from Colorado Springs
You are looking for a brickwall filter. Several methods mentioned above will allow you to approach this, but you will get quite a bit of goofiness right at the cutoff frequency with any of the methods mentioned because of ripple stackup (at least with the methods that have mentioned putting multiple filters in series).
Now, to the point mentioned right up near the top. There is a psychoacoustic effect of very steep filters that is normally unwanted. The psychoacoustician Georg von Bekesy called it something like the 'edge effect', where one's auditory attention is drawn to the edge of the filter, almost as if a tone is present at the edge. This is normally highly undesirable. It actually will have the opposite effect of what you are trying to accomplish, in that you are trying to eliminate something undesirable right at the edge of the filter, but in reality, because of the unnatural cutoff slope, you draw attention to it.
You can try this by putting some pink noise through a couple of lowpass filters in series with the same cutoff frequency for each filter. Then check to see if you don't hear a tonality that matches where the edge frequency is by generating a simple sine tone at that same frequency.
I am not talking about a very narrow band pass filter, but either a high or low pass filter with brickwall like cutoff. I was taught about this by Dr. Tomasz Letowski, a psychoacoustician who has taught at Warsaw as well as Penn St. and currently works for the US Army at the Aberdeen Proving Ground.
(Going off to see if I can find the von Bekesy effect on the internet.....)
Page 21 of this reference talks about this to an extent:
http://people.bu.edu/gallun/teaching/pitch.pdf
It looks like researchers have built upon von Bekesy's work on this topic.
But to convince yourself, just try putting some music or pink noise through the most steep filter you can create and you'll hear this negative effect.
-Scott
Now, to the point mentioned right up near the top. There is a psychoacoustic effect of very steep filters that is normally unwanted. The psychoacoustician Georg von Bekesy called it something like the 'edge effect', where one's auditory attention is drawn to the edge of the filter, almost as if a tone is present at the edge. This is normally highly undesirable. It actually will have the opposite effect of what you are trying to accomplish, in that you are trying to eliminate something undesirable right at the edge of the filter, but in reality, because of the unnatural cutoff slope, you draw attention to it.
You can try this by putting some pink noise through a couple of lowpass filters in series with the same cutoff frequency for each filter. Then check to see if you don't hear a tonality that matches where the edge frequency is by generating a simple sine tone at that same frequency.
I am not talking about a very narrow band pass filter, but either a high or low pass filter with brickwall like cutoff. I was taught about this by Dr. Tomasz Letowski, a psychoacoustician who has taught at Warsaw as well as Penn St. and currently works for the US Army at the Aberdeen Proving Ground.
(Going off to see if I can find the von Bekesy effect on the internet.....)
Page 21 of this reference talks about this to an extent:
http://people.bu.edu/gallun/teaching/pitch.pdf
It looks like researchers have built upon von Bekesy's work on this topic.
But to convince yourself, just try putting some music or pink noise through the most steep filter you can create and you'll hear this negative effect.
-Scott
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- KVRAF
- 2488 posts since 2 Dec, 2004 from Sydney, Australia
For cutting off Low or High end, those are my workhorses. They are the most clean Hipass/Lowpass filter I ever came across so far. Plus they don't need much CPU.Shy wrote:dalor, those are interesting, thanks. never seen/heard anything like it.
I hardly never use 192db though, rockstar_not described the 'edge effect' it creates which is mostly unwanted.
There was also thread searching for a ultrasteep high pass filter needed, and it looked like blocc did the best job compared to some others.
Cowbells!
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- KVRAF
- 1855 posts since 21 Sep, 2004 from Musician, Recording Engineer, Producer
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- KVRist
- 78 posts since 4 Apr, 2005 from Germoney
I remember something from waaaayyyback on Mac OS 9
......there used to be a realtime algorhythm in Prosoniqs SonicWorx Studio that was called "rubberband eq".....until today I was not able to find an EQ that would cut as radically as this thing.... I don't think it will ever be "re-released".....guess Prosoniq is kinda dead by now....
......there used to be a realtime algorhythm in Prosoniqs SonicWorx Studio that was called "rubberband eq".....until today I was not able to find an EQ that would cut as radically as this thing.... I don't think it will ever be "re-released".....guess Prosoniq is kinda dead by now....
myspace.com/droneonline
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god made shit too.
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god made shit too.
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Christian Budde Christian Budde https://www.kvraudio.com/forum/memberlist.php?mode=viewprofile&u=25572
- KVRAF
- 1538 posts since 14 May, 2004 from Europe
Just thrown some IIR-Butterworth filters together. The GUI is quirky, but you should have access to every parameter. The maximal steepness right now is 384dB/Oct, but it would be no problem to extend that to whatever is nessecary...
Download it here
PS: The parameters are optimized for static application. Rapid slider movements might result in some clicking.
Download it here
PS: The parameters are optimized for static application. Rapid slider movements might result in some clicking.
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- KVRAF
- 19156 posts since 13 Feb, 2003 from Vancouver, Canada
I will probably never have a use for this, but I have to grab this! You rock, Christian! 
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- KVRist
- 41 posts since 5 Dec, 2005
and what about GRM bandpass filter ?
http://www.grmtools.org/quicktour/vstqt ... dpass.html
as far as i remember it sounds quite special but cuts like a razorblade
http://www.grmtools.org/quicktour/vstqt ... dpass.html
as far as i remember it sounds quite special but cuts like a razorblade
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- KVRAF
- 19156 posts since 13 Feb, 2003 from Vancouver, Canada
Dude. Christian just made audio history today. 384db/oct. I think the topic can be considered closed.
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- KVRist
- 241 posts since 26 Jul, 2006
yes!, freaikn history!!!, Thanks alot Christian!
this filter sounds so good!!!
you the man
this filter sounds so good!!!
you the man
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- KVRAF
- 2910 posts since 26 Jul, 2005 from dun unda
Sony's Parametric EQ could already do something like that. It's a matter of 'drawing' the dots that warp the flatline.