EQ8 does not cut low freq's

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jasper
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EQ8 does not cut low freq's

Post by jasper » Mon Jan 05, 2015 8:52 pm

I'm looking at it right now, and I'm hearing it, and...
According to the spectral readout on the EQ8, even when low frequencies
are cut at 24dB per octave, the spectral readout still shows
all kinds of activity below the cut point.
There shouldn't anything happening down there, because the EQ is supposedly cutting it.

So either the EQ is not cutting those frequencies, or the spectral readout is wrong.

So we slap on a third party spectral plugin, and it says that the EQ8
is not doing what its knobs say it's doing.
Is there a suggestion as to how many EQ8's should be placed in a row
to achieve a simple Low cut?
AutoFilter seems to work for this, but the task is an EQ task.
Can you please fix the EQ?:)

agent314
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Re: EQ8 does not cut low freq's

Post by agent314 » Mon Jan 05, 2015 9:32 pm

Are you in stereo or midside mode?

pinkpaint
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Re: EQ8 does not cut low freq's

Post by pinkpaint » Mon Jan 05, 2015 9:40 pm

You probably are using a super compressed vst of some kind or sound, for such reasons people like fab filter create EQs with cuts up to I think 92db so if 24db cut isn't working for you I don't think its ableton, I think its your sound, cause I can hi pass with the eq8 and I hear none of the low frequencies on most things at 24db cut.

However, as you said, using the auto filter and an EQ8 usually helps achieve any result you need, and if you know the EQ really well, you can put a the auto filter at any frequency just like the pass on your EQ, because all it is, is a one band EQ, so technically the auto filter is an EQ so it is under the category of EQ tasks. So to use it for such a task would be appropriate, imo.

tedlogan
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Re: EQ8 does not cut low freq's

Post by tedlogan » Mon Jan 05, 2015 9:58 pm

n/m

florian_bl
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Re: EQ8 does not cut low freq's

Post by florian_bl » Mon Jan 05, 2015 10:10 pm

The cutoff frequency of an EQ or any other filter is not defined as the frequency where no signal is left below (or above). It means the frequency where the signal is damped by 6 dB.

How much the frequencies below are really damped or removed has nothing to do with the cutoff frequency. It is a matter of the slope. Unfortunately this frequency is called cutoff frequency in the English language, although it doesn't really cut off anything there a 100 percent.

stringtapper
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Re: EQ8 does not cut low freq's

Post by stringtapper » Mon Jan 05, 2015 10:15 pm

florian_bl wrote:The cutoff frequency of an EQ or any other filter is not defined as the frequency where no signal is left below (or above). It means the frequency where the signal is damped by 6 dB.
I think it's generally accepted as closer to 3dB, which corresponds to the minimum amount of change in amplitude that is perceptible by most ears.

But yeah, what he said.
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jasper
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Re: EQ8 does not cut low freq's

Post by jasper » Mon Jan 05, 2015 10:17 pm

Wow I didn't even know the eq has a mid/side mode.
That's awesome!:)
There is still this thing though where it's set
to cut everything below some freq while
its spectrum readout shows the cut frequencies
as still present.

I'm loving the fact that mid/side eq'ing is built into
this eq.

jasper
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Re: EQ8 does not cut low freq's

Post by jasper » Mon Jan 05, 2015 10:24 pm

stringtapper wrote:
florian_bl wrote:The cutoff frequency of an EQ or any other filter is not defined as the frequency where no signal is left below (or above). It means the frequency where the signal is damped by 6 dB.
I think it's generally accepted as closer to 3dB, which corresponds to the minimum amount of change in amplitude that is perceptible by most ears.

But yeah, what he said.
I'm using the "x24" low cut on band 1.
Band 1 is up at 100Hz.
There's stuff bouncing around above -12db all the way down to
the lowest freqs on the spectrum.
At 24db per octave (x24) there shouldn't be any 30, 40, 50 hz.
And at -12db ? That's loud. Just saying.

florian_bl
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Location: Austria

Re: EQ8 does not cut low freq's

Post by florian_bl » Mon Jan 05, 2015 10:30 pm

You are right, stringtapper. 3 dB is the right amount. 6 dB per octave is the slope of a first grade filter. Good to bring these things back to mind again.

Tagor
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Re: EQ8 does not cut low freq's

Post by Tagor » Mon Jan 05, 2015 10:36 pm

also interested cutting under 30 hertz freqs in a range to -120 dbfs with eq8
getting nice results with the 4x hipass curve, but it sounds not neutral.

stringtapper
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Re: EQ8 does not cut low freq's

Post by stringtapper » Mon Jan 05, 2015 10:54 pm

jasper wrote:
stringtapper wrote:
florian_bl wrote:The cutoff frequency of an EQ or any other filter is not defined as the frequency where no signal is left below (or above). It means the frequency where the signal is damped by 6 dB.
I think it's generally accepted as closer to 3dB, which corresponds to the minimum amount of change in amplitude that is perceptible by most ears.

But yeah, what he said.
I'm using the "x24" low cut on band 1.
Band 1 is up at 100Hz.
There's stuff bouncing around above -12db all the way down to
the lowest freqs on the spectrum.
At 24db per octave (x24) there shouldn't be any 30, 40, 50 hz.
And at -12db ? That's loud. Just saying.
Have you put an actual Spectrum plugin after the EQ8?

I've got an instance of Operator playing a sine wave at C1 (roughly 65Hz) and I have an EQ8 after it with a cutoff frequency of 120Hz and a Q of around 0.70. The band is set to high-pass with the 48dB slope ("x4") option. Now the EQ8's spectrum view is showing the C1 tone as peaking at around -3dB, but the Spectrum device I have after it is showing the C1 peaking at around -54dB.

So maybe it's an issue with the EQ8's spectrum view?

And if so, a case of eyes getting in the way of ears maybe? :wink:

EDIT: I said low-pass and meant high-pass.
Last edited by stringtapper on Tue Jan 06, 2015 6:46 pm, edited 1 time in total.
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stringtapper
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Re: EQ8 does not cut low freq's

Post by stringtapper » Mon Jan 05, 2015 11:36 pm

And the wind blew…

:lol:
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tylenol
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Re: EQ8 does not cut low freq's

Post by tylenol » Tue Jan 06, 2015 4:49 am

jasper wrote: I'm using the "x24" low cut on band 1.
Band 1 is up at 100Hz.
There's stuff bouncing around above -12db all the way down to
the lowest freqs on the spectrum.
At 24db per octave (x24) there shouldn't be any 30, 40, 50 hz.
And at -12db ? That's loud. Just saying.
Can you post a screenshot with a spectrum both before and after the EQ?

Steve Glen
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Re: EQ8 does not cut low freq's

Post by Steve Glen » Tue Jan 06, 2015 5:30 am

Equing is not the magical process that it looks like in a display. Audio signals can be very complex and there are many different types of filters to put in eqs.

Practically, I recommend doubling up the eqs, if you really need, with serial processing. I find that either an exact duplicate or, in the case of HP, set to a lower frequency works nicely.

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stringtapper
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Re: EQ8 does not cut low freq's

Post by stringtapper » Tue Jan 06, 2015 8:44 pm

Why would you use two EQ8s when you can just enable the second filter set to high-pass? Same results.
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