Equalizer s 101
Equalization 101 is in order.. class is in session...
First a look at the different types of Eq’s
Graphic: usually in…
10 band
15 band
28 band
31 bands
Para graphic: Mostly available in computer programs only
Any number of bands.. usually 10 or less
Variable center frequency with variable slope
Semi parametric: Mostly found on inexpensive mixers channel eq.
Any number of bands ..usually 1, 2 or 3
Variable center frequency
Fixed slope
Gain control
Fully parametric : Can be found on more expensive consoles, and rack mount units
Any number of bands usually 2-10
Variable center frequency
Variable “Q�
Variable cut/boost
Selectable “shelf� or “bell� curves
This covers the majority of the conventional equalizers available today. Now lets look at some of those foreign terms:
Equalize: is the process of changing the frequency envelope of a sound. In passing through any channel, temporal/frequency spreading of a signal occurs. Etymologically, it means to correct, or make equal, the frequency response of a signal.
Frequency band: A group of frequencies with a specific center frequency, that usually exhibits a specific db (decibel per octave) falloff in both directions from the center frequency.
Slope: Imagine a ski hill.. now imagine the bunny hill.. a VERY gradual slope … this would be like a slope with a “Q� of
First an observation...
"Using a 15 band EQ is like carpet bombing where a sniper rifle would suffice..." Not my quote but as usual borrowed without permission and since I can't remember who said it .. without credit as well... but a very accurate statement. I do know it was on the PSW 'LAB' forum though...
The ISO centers on a 15 band EQ very from a few hundred hz to thousands of hz per frequency covered by a single fader... that means if (for instance) you were having an issue with the first harmonic of the kick drum, you would have to cut both the 63 and 100 hz faders effectively cutting frequencies from 40 to 160 hz! ALL those frequencies and all we wanted to do was cut 80 hz...We would probably have had to do more cutting than if we were just treating 80 hz also because of the nature of the location within the filters location and the nature of the slope on each adjacent band and the fact that 80 hz falls between bands... NOT good for the sound... not good for the feedback elimination...The higher the frequency the more frequency spectrum is covered.Take for instance the 10K band on the DBX 215 eq. That band covers 9000 hz! from 6.3k all the way to 20khz! That's a LOT of frequencies covered by a single fader!
A 31 band EQ is better... but still has the problem of ISO centers that often don't fall on the feedback locations and cut way more than is necessary to address the feedback. This is often the solution, but there is a better way... Lets examine fully parametric equalization.
In fully parametric eq's even though you typically have fewer bands you can do more and be more precise in doing so. A parametric EQ allows you to zero in on the frequency you want to address (with digital eq's to within a few hertz) and allows you to apply a very very narrow cut or boost all the way up to a nearly 20-20,000 hz cut or boost.. with a single band...So with a PEQ you can zero in on the problematic frequency...start with a narrow cut and adjust the "Q" (amount of the frequency spectrum you want to affect) till the problem is addressed with the minimum amount of evasiveness to the frequency spectrum.
I typically monitor the FBX screen to identify feedback areas and adjust them with a PEQ on the fly...the FBX screen gives you the frequency in hz the feedback occurred at and shows the amount of cut and "Q" of the cut so it's simple to mimic with a PEQ channel.
A variable high and lo pass filter can be a great asset in an EQ as well... and can take actually add many bands of effective EQ in a single knob.
Ok for the sake of argument here I will add a potential cost effective solution.. even though it is an off topic piece...If DBX had such a piece I would suggest it.. but alas...
http://www.zzounds.com/item--BEHDEQ2496
check out the feature list... and yes.. it's disposable should you have any issues out of warranty but hey I have not had a failure in any of their stuff I posses yet...
First a look at the different types of Eq’s
Graphic: usually in…
10 band
15 band
28 band
31 bands
Para graphic: Mostly available in computer programs only
Any number of bands.. usually 10 or less
Variable center frequency with variable slope
Semi parametric: Mostly found on inexpensive mixers channel eq.
Any number of bands ..usually 1, 2 or 3
Variable center frequency
Fixed slope
Gain control
Fully parametric : Can be found on more expensive consoles, and rack mount units
Any number of bands usually 2-10
Variable center frequency
Variable “Q�
Variable cut/boost
Selectable “shelf� or “bell� curves
This covers the majority of the conventional equalizers available today. Now lets look at some of those foreign terms:
Equalize: is the process of changing the frequency envelope of a sound. In passing through any channel, temporal/frequency spreading of a signal occurs. Etymologically, it means to correct, or make equal, the frequency response of a signal.
Frequency band: A group of frequencies with a specific center frequency, that usually exhibits a specific db (decibel per octave) falloff in both directions from the center frequency.
Slope: Imagine a ski hill.. now imagine the bunny hill.. a VERY gradual slope … this would be like a slope with a “Q� of
First an observation...
"Using a 15 band EQ is like carpet bombing where a sniper rifle would suffice..." Not my quote but as usual borrowed without permission and since I can't remember who said it .. without credit as well... but a very accurate statement. I do know it was on the PSW 'LAB' forum though...
The ISO centers on a 15 band EQ very from a few hundred hz to thousands of hz per frequency covered by a single fader... that means if (for instance) you were having an issue with the first harmonic of the kick drum, you would have to cut both the 63 and 100 hz faders effectively cutting frequencies from 40 to 160 hz! ALL those frequencies and all we wanted to do was cut 80 hz...We would probably have had to do more cutting than if we were just treating 80 hz also because of the nature of the location within the filters location and the nature of the slope on each adjacent band and the fact that 80 hz falls between bands... NOT good for the sound... not good for the feedback elimination...The higher the frequency the more frequency spectrum is covered.Take for instance the 10K band on the DBX 215 eq. That band covers 9000 hz! from 6.3k all the way to 20khz! That's a LOT of frequencies covered by a single fader!
A 31 band EQ is better... but still has the problem of ISO centers that often don't fall on the feedback locations and cut way more than is necessary to address the feedback. This is often the solution, but there is a better way... Lets examine fully parametric equalization.
In fully parametric eq's even though you typically have fewer bands you can do more and be more precise in doing so. A parametric EQ allows you to zero in on the frequency you want to address (with digital eq's to within a few hertz) and allows you to apply a very very narrow cut or boost all the way up to a nearly 20-20,000 hz cut or boost.. with a single band...So with a PEQ you can zero in on the problematic frequency...start with a narrow cut and adjust the "Q" (amount of the frequency spectrum you want to affect) till the problem is addressed with the minimum amount of evasiveness to the frequency spectrum.
I typically monitor the FBX screen to identify feedback areas and adjust them with a PEQ on the fly...the FBX screen gives you the frequency in hz the feedback occurred at and shows the amount of cut and "Q" of the cut so it's simple to mimic with a PEQ channel.
A variable high and lo pass filter can be a great asset in an EQ as well... and can take actually add many bands of effective EQ in a single knob.
Ok for the sake of argument here I will add a potential cost effective solution.. even though it is an off topic piece...If DBX had such a piece I would suggest it.. but alas...
http://www.zzounds.com/item--BEHDEQ2496
check out the feature list... and yes.. it's disposable should you have any issues out of warranty but hey I have not had a failure in any of their stuff I posses yet...
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