VIDEO: God, Sex, and Low Cut Filters

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most interesting things I've seen about EQs.

I think the problem esp with high frequencies (or a short pulse) is the result of the following:

As I know:

normally

in an EQ you go by Fourier-Transformation from the (mathematical) room where the amplitude of the waveform is shown in dependance of the place you are to the (mathematical) room, in which the amplitude of the waveform is shown in dependance of the frequency.

The Fourier Analysis/Transformation is based on: You can build every periodic function (in our case Waveform) by addition of an infinite! number of infinite! precise sinus-functions (of different frequencies, from the mathematical sight of view: if necessary an infinite! big frequency).

For ex.: If you wanna build a perfect rectangle Waverform, you actually need a infinite small sinus-Wave to build the edges of the rectangle. But in practise: that's not possible.

I think:

- Fourier transformation in analog EQs: you cannot go to an infinite big frequency cause of limitations of the electronic parts (capacities/inductances of all parts like transistors, resistors, conducting pathes...), and the sinus waves you get are never inifinte precise, so you will always loose some informations doing this transformations.

Fourier transformation in digital EQs: also: the sinuswaves you get (if you go from the place-room to the frequency-room) are never infinite precise & the (clock?) frequency you work with (96kHz...) will limit the frequency (of the sinuswaves) that can be used to build our original signal.

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Last edited by Vortifex on Tue Apr 23, 2019 9:37 pm, edited 1 time in total.

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Vortifex wrote: Fri Dec 21, 2018 12:42 am Wait, how does highpassing decrease the headroom? *mind blown*
It decreases the required headroom.
Low freqs need a high amplitude, so they eat up the available headroom. Shave off some lows, and you can increase the overall volume without clipping.
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Last edited by Vortifex on Tue Apr 23, 2019 9:37 pm, edited 1 time in total.

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Vortifex wrote: Fri Dec 21, 2018 12:38 pmMaybe you didn't watch the video [...]
Spot on, I did not. But have now! I see what you mean...

He has set the filter to "brick-wall", while -18dB/Oct would be more appropriate / realistic. Anyway, the RMS stays the same but peak level increases! That indeed is typically wasting your headroom.

Only thing I can think of why this happens is that the filter shifts some phases in the midrange.
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Phase is the key. High-passing everything is in my experience not at all a good practice. Not sure how it ever became a "rule" of any kind. Some sources absolutely benefit from being frequency range restricted but this is not universally true for everything. You can easily run into real issues especially if you are lazy and always put the same high-pass on everything and have the corner frequency always the same.
"Wisdom is wisdom, regardless of the idiot who said it." -an idiot

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The practice comes from analog consoles which have a neat switch on each channel engaging a -18dB/oct@75Hz HPF.

In the analog world the phase shifts aren't that problematic. We have plenty of headroom there since our mixing target is 0dB VU and 25dB of headroom to play with.
Compare that to the digital world where the mixing target seems to be 0dB FS RMS.

So keep your brain switched on for each decision you make. That's what eq chameleon says as well. A rumble at -30dB does nothing to your base drum at -3dB
Last edited by BertKoor on Mon Dec 24, 2018 8:11 am, edited 1 time in total.
We are the KVR collective. Resistance is futile. You will be assimilated. Image
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I disagree. Phase can cause all kinds of problems in the analogue domain too. It's not just about headroom. You get problems from group delay in the analogue domain as well. It's just how filters work.
"Wisdom is wisdom, regardless of the idiot who said it." -an idiot

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Like with all things, still, there are no hard rules for anything.

I use a 6db/oct highpass on nearly every source at very varying frequencies, and along with 3D placement by means of reverb it's maybe the biggest contributor of clarity in my mixes, IMO.

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6dB per octave filters are _the best_ for corrective use in my opinion. The phase wobble and group delay are absolutely minimized with these. Another option is using shallow shelves.

The real problems start when people have 24dB/octave filters all over the place.

Our very own resident guru aciddose has one of the best filter plugins out there and I constantly use it's 6dB/octave filters, both LP and HP.

http://xhip.net/effects/

It's the Xhip RC Filter plugin in that pack.

Another notable gentle filter is the Airwindows Hermepass filter.. so if one must do a lot of filtering, that one is also highly recommended.
"Wisdom is wisdom, regardless of the idiot who said it." -an idiot

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bmanic wrote: Wed Dec 26, 2018 3:53 amOur very own resident guru aciddose has one of the best filter plugins out there and I constantly use it's 6dB/octave filters, both LP and HP.
Thanks bmanic! Didn’t realize this was adjustable below 20Hz.
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