Grasping 3 band eq

maxman65

maxman65

Member
Hi . Trying to get my head around how to cut frequencies in the right places . My first real issue here is that I still don't understand on the zoom r16 whether a selected frequency to cut is solely cutting that frequency or everything else below it . Eg if I cut a piano at 150hz does that mean it's cutting everything down from 150hz to 40hz by the selected dB of say -3 . Or is it just cutting 150hz . Ie is it that you can only cut 3 specific frequencies on a 3 band eq. Sorry guys I really don't get it . Can someone tell me in extremely simple and idiot proof terms . Much appreciated
 
If it's a high-pass filter, it's cutting everything below that frequency by (x) dB per octave -- a 6dB filter will be down 6dB around 75Hz, 12dB down by 35Hz, around 18dB by the time you get to subsonics.

If it's a shelf, it's affecting everything below that frequency roughly equally.

If it's a parametric control (a.k.a. bell or peak, notch filter, etc.), you can determine how wide out from the center frequency is affected.

I'm not familiar with the EQ on the r16 -- But I'd imagine you can choose what type of filter it is. Or there might simply be a HPF, LPF and a variable mid (heck, maybe a fixed mid - again, I'm not familiar).

[EDIT] Page 38 of the manual -- It appears as if you have a high and low shelf with a selectable frequency and a parametric mid (selectable frequency and bandwidth).
 
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maxman65 said:
Hi . Trying to get my head around how to cut frequencies in the right places . My first real issue here is that I still don't understand on the zoom r16 whether a selected frequency to cut is solely cutting that frequency or everything else below it . Eg if I cut a piano at 150hz does that mean it's cutting everything down from 150hz to 40hz by the selected dB of say -3 . Or is it just cutting 150hz . Ie is it that you can only cut 3 specific frequencies on a 3 band eq. Sorry guys I really don't get it . Can someone tell me in extremely simple and idiot proof terms . Much appreciated
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Ok but in simple terms is a selected frequency cutting a range of frequencies or a specific frequency . I really need this explained very simply .by way of example what does a cut of 3db at 150hz actually do on that machine
 
It's a bit difficult to tell from the manual but an educated guess is the Zoom R16 has 3 different eq profiles. There is a low shelf, a sweepable mid, and a high shelf. To answer your question specifically, if you cut your "low-shelf" at 150hz it's more than likely a gradual predetermined curve that reduces low frequencies between two fixed points. As you mentioned, perhaps between 150hz and 40hz. It is not however cutting only 150hz.

Conversely, a "low-cut" filter (as opposed to a low-shelf filter) reduces everything beneath the cut-off point. That is to say, everything below 150hz is cut-off, although the severity of the cutoff (slope) usually can be adjusted. A "low cut" filter can be a somewhat gradual slope, all the way to absolutely nothing below the chosen frequency. A 24-octave "low cut" filter at 150hz, pretty much guarantees nothing below 150hz is heard. Again, however, I'm pretty sure that the Zoom is a low shelf.

The sweepable mid's on your Zoom will sweep down to 150hz and in so, you could set the midpoint at 150hz and subtract audio at just the 150hz area but in varying widths, usually perceived as right-side-up or upside-down silhouettes of a church bell.
 
Ok does that mean I would best imagine the (selected )150hz as the apex of a bell shape which tapers off frequencies below and above until it reaches the next (mid ) default parameter at I think 1k and similarly to 40hz below in a kind of symmetry. I guess the midpoint between 1k and 40hz would be symetrical rather than a kind of offset bell shape . Trying to visualise this
 
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maxman65 said:
Ok does that mean I would best imagine the (selected )150hz as the apex of a bell shape which tapers off frequencies below and above until it reaches the next (mid ) default parameter at I think 1k and similarly to 40hz below in a kind of symmetry. I guess the midpoint between 1k and 40hz would be symetrical rather than a kind of offset bell shape . Trying to visualise this
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Low-cut filter. Low-cut shelf. Sweepable cut at 150hz.
 
Load up EQ then Spectrum analyzer after it, add a white noise generator. Now you can see exactly what your EQ moves are doing.

For me a 3band EQ is practically useless unless I'm working with tracks that are recorded in good rooms, I'm needing to cut very aggressive at 150hz - 250hz with a very narrow Q (notch) quite a lot of the time, with a compensatory 1-5k balance
 
The R16 Hi and Low EQ frequencies appear to be fixed, much like Bass Mid Treble on most amps. I don't understand the Mid EQ frequency 1..0kHz, I didn't see how to adjust the Mid frequency point in order to apply the Q-Factor adjustment.

eq.jpg
 
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Definately has 3 bands which can be cut or boost up to - and + 12db .each band can also be selected to a different frequency . Been playing around with it . Getting a slight handle on the whole equalisation thing
 
Good.

That EQ MID Q looks like it'll get you any frequency with as wide or narrow a bandwidth as you need for zeroing in on what you need to tame. I see the cut and boost explained in the manual but it doesn't detail how to select those frequencies. That must be obvious when in the EQ displays.
 
Ok just realised what you're talking about . Yes there is a q number which default at 0.5 from memory. Do you know whether this would relate to a narrow /wide tapered bell curve Type eq or a cut off . I'm guessing a higher value for q broadens the width ? I'm still struggling with the notion of how this would look and work in effect . As yet I've not played with the q variable
 
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The Q factor controls the steepness of the curve. A low Q factor gives you a wide band. A high Q factor gives you a very sharp band of control. This site shows you what it looks like: Q Factor in EQ. The high and low are shelf EQs. So you end up with something like this:

EQ.jpg

You can move the points, and using Q factor, you make the peak change width. For example if you had some 60 cycle hum, you could put the mid EQ on 60 Hz, and use a high Q factor to minimize the effect on other frequencies.
 
Excellent many thanks . I guess that begs the question is the default 0.5 q value considered low - ie broader /flatter bearing in mind there is no graphic representation of the curve on the r16
 
maxman65 said:
Excellent many thanks . I guess that begs the question is the default 0.5 q value considered low - ie broader /flatter bearing in mind there is no graphic representation of the curve on the r16
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I'd guess that value would correspond to a very narrow, pointed curve. Higher values would widen it to more of a full bell shape.

Have you ever used an AM radio in an old car? Moving the tuning knob quickly from side to side or in a longer sweep produces an audio effect similar to what might be represented graphically with these EQs with a very narrow Q setting being "swept" back and forth.
 
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I'm not sure that contradicts what talisman was alluding to. seemed that a higher value q steepens the curve ?. I wondered whether q is an industry standard value and as such whether q = 0.5 is considered low and therefore wide shallow ? There is no way on this mutitrack that the function of q can be seen graphically
 
That may be the case. Without a graphic visual and no hands on at my end it's difficult to determine. You should be able to determine this audibly by playing around with it. Very narrow, pointed, steep curves will lack the fuller sound of a broader curve. With a parametric EQ using High and Low Pass filters you can actually use this feature to get a sort of old school AM radio sound using narrow curves.
 
Ok just checked the machine Q variable goes from 0.1 to 1. I figure they chose a mid point as the default of 0.5 . An average width curve then (whatever that looks like ) any offers ? Yes I'll just play with it and see what happens
 
maxman65 said:
Ok just checked the machine Q variable goes from 0.1 to 1. I figure they chose a mid point as the default of 0.5 . An average width curve then (whatever that looks like ) any offers ? Yes I'll just play with it and see what happens
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There are two often misunderstood components of a sweepable (parametric) eq, at least as a basic and broad brushstroke. There is the "Q" and there is the bell. In your case, I think the bell is non-adjustable but for the record bell "shapes" are measured in octaves. The lower octave bells have a more gentle drop-off and or rise, on either side of the bell itself. A higher octave bell provides for a much sharper, steeper drop-off or rise. The "Q" then determines the width of the bell, whatever shape the bell might be.

So, in simple terms, the bell is shapable and the "Q" adjusts the width of the shapable bell. I can provide pics if that'll help.
 
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