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EQ question re- size of frequency range to adjust

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EQ question re- size of frequency range to adjust

Postby GS1 » Tue Jun 12, 2018 4:42 pm

Been doing a lot of online research and am wondering about Q-related concepts i.e.some articles suggest a boost/cut/shelf in a range wider than the less -than -an-octave>2-3 octave range the Q #s refer to i.e.600-800 hz......do you cut/boost this wide or is this referring to a) using a shelf in this area or b) "sweeping" in this wide an area to find where to boost/cut within the usual Q parameters?I understand the high pass filter used to eliminate all frequencies below 80-100 hz but do you do this wide a boost/cut in other frequency ranges as well or is this reserved for shelf filtering where the wide range is boosted/cut by a set amount but not eliminated or significantly emphasized....??
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Re: EQ question re- size of frequency range to adjust

Postby Hugh Robjohns » Tue Jun 12, 2018 5:24 pm

GS1 wrote:Been doing a lot of online research...

Add these to your reading list: https://www.soundonsound.com/techniques/using-equalisation https://www.soundonsound.com/techniques/using-your-sequencers-equalisers

I fear that is some confusion about different types of equalisation/filtering, and the terminology involved.

Q is shorthand for 'quality factor' which is itself an engineering term that is used to describe the bandwidth of a filter. Those with a more musical outlook tend to describe the bandwidth in terms of octaves. A wide bandwidth has a low Q, and vice versa.

How wide the bandwidth needs to be will depend on what you're trying to achieve, but in general terms it's usually advisable to use wide bandwidths (low Qs) with small amounts of gain when boosting, and narrower bandwidths (higher Qs) with greater attenuation when cutting.

A shelf equaliser raises or cuts the level of all frequencies from the eq's frequency setting -- so a bass shelf raises or lowers the low end, while a high shelf does the same for the high end, as illustrated in this plot. A shelf equaliser does not have a 'bandwidth' control, as such, although some allow the steepness of the slope to be adjusted.
Image

The alternative is a 'bell' equaliser which raises or cuts a defined region of frequencies, with the frequency control setting the centre point, and the bandwidth (or Q) the width and steepness of slope.
Image

Some bass and high shelf equalisers can be switched between shelf and bell modes.

I understand the high pass filter used to eliminate all frequencies below 80-100 hz...

High-pass (and low-pass) filters are used to remove elements outside the wanted audio region. The 'corner' frequency (where the filtering starts) can often be adjusted, and sometimes the steepness of the slope, but there is no bandwidth control.
Image
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Re: EQ question re- size of frequency range to adjust

Postby GS1 » Tue Jun 12, 2018 9:58 pm

Really appreciate your taking the time to reply in detail and for posting the links/diagrams....I am working w/the EQ settings on a TASCAM DP-008 ex and a ZOOM RT 223;the latter has specific filters and a bunch of settings for compression/EQ while the TASCAM allows for adjusting the comp/EQ without actual filters;I'm thinking the filter effects are easily simulated given the amount of adjustments you can make....so having this kind of info re-range size to deal with is necessary unlike using preset filters w/adjustable Q and other settings.....to return to the question again,would I cut or boost a given range as wide as the #s given (I.e.between 60-100) or some smaller frequency range within the larger one indicated i.e. 70-90 which would be an octave or Q 1.4...If I cut or boosted 60
-100 this would be Q .7 which I see listed as the widest area on the info I have re-Q#s......I'm assuming re-"cut narrow/boost wide"that that the higher Q #s are for surgical cuts so I wouldn't be cutting 20-40hz I.e 1-2 oct but would I boost a wide area like that?I'm seeing larger areas indicated for boosting/cutting i.e.cutting between 160-600 for the kick drum ....this would Iindicate finding an area within this larger one that has a more pronounced presence and taking it down somewhat or eliminating a small area within it completely using the Q#s as a gudeline I'm assuming....a wide boost would still be within 2 octaves at most in a given frequency area within the larger one indicated that "sweeping" would locate;shelf boosts/cuts would be about reducing or increasing the frequencies above or below a given one by a given fixed amount and could affect a large range given the center frequency set if I'm not mistaken.....continued clarification about these concepts is greatly appreciated...
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Re: EQ question re- size of frequency range to adjust

Postby Hugh Robjohns » Wed Jun 13, 2018 8:57 am

GS1 wrote:...to return to the question again, would I cut or boost a given range as wide as the #s given (I.e.between 60-100) or some smaller frequency range within the larger one indicated i.e. 70-90 which would be an octave or Q 1.4...If I cut or boosted 60
-100 this would be Q .7 which I see listed as the widest area on the info I have re-Q#s...

I'm sorry... I'm really struggling to understand your question because it's a solid wall of text...... but fundamentally, there is no absolute right or wrong answer here. You determine the EQ bandwidth depending on the requirements of the material and what you're trying to achieve.

Do you need to alter the level of a very narrow band of frequencies, perhaps to reduce an annoying resonance, say, or do you need to alter a broad band of frequencies to make a sound more or less prominent in the mix against other instruments and sounds? That's something only your ears -- combined with some experience -- can decide.

...I'm assuming re-"cut narrow/boost wide"that that the higher Q #s are for surgical cuts

Our ears are certainly much more sensitive to boosts in general, and smaller bandwidth boosts particularly so. It's because they sound resonant and we can spot that quite easily. So if you have to boost, keep the gains small and the bandwidths wide.

However, it's usually much better to reduce elements we don't like, rather than boost those we do, and that's because our ears tend not to notice or mind narrow ranges of missing frequencies, even with quite large amounts of cut.

So yes, save the high-Q (narrow bandwidth) settings for 'surgical' cuts!

I'm seeing larger areas indicated for boosting/cutting i.e.cutting between 160-600 for the kick drum

The modern kick drum sound is actually quite artificial, and it has become the norm to use a relatively narrow boost to promote the fundamental resonance around 80Hz, and then to scoop out a wide bandwidth over the midrange from about an octave above (160Hz or so) up to around 1kHz. Another fairly narrow peak is usually then added to emphasise the beater click around 3kHz... in broad terms (every drum is different!). This practice shapes the kick drum tone into the sound we expect in a modern recording, and leaves space in the spectrum for the bass and other instruments.

...shelf boosts/cuts would be about reducing or increasing the frequencies above or below a given one by a given fixed amount and could affect a large range given the center frequency set if I'm not mistaken....

Shelf EQs don't have a 'centre frequency', they have a 'corner' frequency -- meaning (in simple terms) the frequency region where the shelf levels out. In some EQs this is adjustable, but in many the corner frequencies are fixed, often at 100Hz and 10kHz. That being the case, the high-shelf covers a nominal one octave, while the low-shelf covers a bit over two octaves... However, because of the gentle slope into the shelf, the audible effect actually spans several octaves.

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Re: EQ question re- size of frequency range to adjust

Postby GS1 » Thu Jun 14, 2018 12:11 am

Thanks again for the continued info esp re-the kick drum -when you use the term "scoop out" the 160-11k range you're referring to using a shelf set @ 160 or @1k to reduce this area rather than a filter type cutting out of the whole 840 hz area??

I'll make sure to space the text....

I found some more online info re-Q where areas as wide as 10 octaves are shown as possible options ...this would be an extreme situation where more often the Q used for wide boosting would be between 1-2 octaves...?
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Re: EQ question re- size of frequency range to adjust

Postby The Elf » Thu Jun 14, 2018 7:20 am

GS1 wrote:Thanks again for the continued info esp re-the kick drum -when you use the term "scoop out" the 160-11k range you're referring to using a shelf set @ 160 or @1k to reduce this area rather than a filter type cutting out of the whole 840 hz area??
'Scoop' is what it implies. Imagine taking a scoop out of the middle of a tub of ice cream.

In other words you would use a parameteric EQ to 'scoop' out a range of frequencies in the middle of the spectrum.
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Re: EQ question re- size of frequency range to adjust

Postby Hugh Robjohns » Thu Jun 14, 2018 8:52 am

GS1 wrote:...when you use the term "scoop out" the 160Hz - 1kHz range you're referring to using a shelf set @ 160 or @1k to reduce this area rather than a filter type cutting out of the whole 840 hz area??

Shelf equalisers raise or lower the extreme top and bottom of the spectrum, as previously explained. This 'scooping' requires a mid-band 'bell' type of equaliser (a parametric mid band) set with a moderately wide bandwidth (two to three octaves or so) to reduce a region centred somewhere around about 300-500Hz.

I'll make sure to space the text....

Thanks -- it really does help to separate the different points and make understanding easier.

I found some more online info re-Q where areas as wide as 10 octaves are shown as possible options

Yes, it might well be possible to have a bandwidth control offer than much, especially with some digital equalisers. However, given the entire audio band (20Hz to 20kHz) is only ten octaves wide, an EQ section set that wide would effectively become a simple gain control, adjusting the level of the whole audio signal rather than just some selected part of it!!

...more often the Q used for wide boosting would be between 1-2 octaves...?

Yes, three octaves might be useful from time to time, but usually one or two octaves is wide enough for creative tonal shaping duties...

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Re: EQ question re- size of frequency range to adjust

Postby Zukan » Thu Jun 14, 2018 10:50 am

I really think you are overthinking this. All you need is to understand how various equalisers work and when to use them. The rest is dependent on content being processed, your ears and your tastes.
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Re: EQ question re- size of frequency range to adjust

Postby Kwackman » Thu Jun 14, 2018 3:11 pm

The previous poster is too modest to point to his own excellent tutorials.
Have a look here...
https://theaudioproductionhub.pivotshar ... 0043/media
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Re: EQ question re- size of frequency range to adjust

Postby GS1 » Thu Jun 14, 2018 4:36 pm

Appreciate all the replies over here being new to forum + getting a chance to hear expert advice...

Actually just started working w/the mixing/mastering settings available on the TASCAM DP-008 yest + found that the built- in EQ ,while allowing for usage w/track inputs initially,then again when mixing down to stereo master track and a third time to EQ the stereo master,only allow for setting a given frequency #,for high/low ranges and adj the amt of dB boost/cut(the EQ settings on the ZOOM RT223 are more sophisticated and relate directly to what's being discussed here)....

I'm wondering about the way the DP-008ex interprets the frequency # you specify in terms of the focus on Q here i..e .does it use the number in a wide Q sense to adjust the frequencies around it or in a high Q context where the specific frequency itself is targeted ....if anyone has exp w/the unit or other similar ones like this....also given the type of EQ available to what extent high pass filtering/shelf EQ'ng would be able to be simulated ...

I'm thinking that I'll only be able to do so much w/what's available then transfer the stereo master to a file and do the more involved EQ'ng w/something like Audacity online.,..

The compressor settings on the DP-008ex are much more detailed and have adjustable parameters within the 3 bands....as well as a lot of presets to work with + I'm thinking between the extent to which I can EQ tracks + what the compressor settings will do I'll be able to get things sounding close to the way I want..

Again much thanks to everyone for reading this post and replying....my situation is that of a musician w/a lot of tracks ready to market who's been focused on the material up to now ....

Just been making little keyboard /drum machine demos of tracks to listen to; now moving into the world
of sound engineering/production so any feedback in terms of things covered here is really appreciated
- thx again!!
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Re: EQ question re- size of frequency range to adjust

Postby Sam Spoons » Fri Jun 15, 2018 8:35 am

The eq on the DP-008 appears to be a simple high or low shelf so doesn't have a q setting.
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Re: EQ question re- size of frequency range to adjust

Postby GS1 » Fri Jun 15, 2018 5:15 pm

Thx for the reply-Have you used the EQ on it much?

In terms of setting the # for the frequency range,do you think it means-

-the center of a wide Q area that gets cut/boost either uniformly or sloped toward this #

Or-


The top or bottom frequency for the range i.e.for the low range between 32 h + 1.6 kHz if I was to set it @ 100hz would that affect 32hz>100 hz (i.e.w/the dB gain @ -12dB it would act as a high pass filter) or would that affect 100hz up....?
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Re: EQ question re- size of frequency range to adjust

Postby Sam Spoons » Sat Jun 16, 2018 8:50 am

Neither but closer to the latter, it's a low/high shelf. The freq control changes the point where the eq starts to affect the signal the but the manual does not say precisely how it works. It doesn't act as a HPF/LPF as the maximum attenuation is 12dB and an HPF/LPF will continue to increase it's attenuate at it's designed rate until, effectively, no signal is passed.

I refer you back to Hugh's excellent earlier reply for detail.

I had a DP-02 for a while not the DP-008, It was a decent bit of kit but I couldn't comment on specifics as I didn't actually use it for anything other than notepad recordings.
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Re: EQ question re- size of frequency range to adjust

Postby Hugh Robjohns » Sat Jun 16, 2018 9:21 am

GS1 wrote:In terms of setting the # for the frequency range,do you think it means-
-the center of a wide Q area that gets cut/boost either uniformly or sloped toward this #
Or-
The top or bottom frequency for the range

The latter.

The EQ on the DP008 is a high/low shelf as I described earlier:

Image

The frequency numbers refer to the area where the shelf starts to level out -- roughly 200Hz and 6kHz in the diagram above.

if I was to set it @ 100hz would that affect 32hz>100 hz

Yes.

(i.e.w/the dB gain @ -12dB it would act as a high pass filter

NO! A high-pass filter is a very different kind of EQ, as I described earlier.

The DP008 has high and low shelf equalisers. They are used to raise or lower a specific region of frequencies by a set amount (measured in decibels) as per the diagram. So, for a low-shelf everything below the corner frequency is raised by 6dB or whatever.

A high-pass (or low-pass) filter can not boost the level at all, and simply turns down everything below the corner frequency -- but with the important difference that there is no levelling out (as there was with the shelf); the further you move away from the corner frequency, the more the signal is attenuated.

Image

Shelf equalisers are used to alter the overall tonality by giving a gentle lift (or cut) to the very highest or lowest parts of the spectrum.

A high-pass filter is used to remove unwanted very low frequencies, such a rumbles or wind noise etc... Very different tool for a very different job, and not available on the DP008.

The DP008 doesn't have a mid-band bell or parametric equaliser, either, and it doesn't have bandwidth or Q controls.

It just has a very simple two-band equaliser with high and low shelf options, both with adjustable gain (up to +/-12dB), and movable corner frequencies.

The low shelf defaults to a corner at 350Hz, but can be moved down to 32Hz (where you probably won't hear any effect) up to 1.6kHz (where it will affect the mid range as well as the bass).

The high-shelf defaults to a corner at 5kHz, but can be moved up to 18kHz (where you probably won't hear any effect) and down to 1.7kHz where it will affect the high mids as well as the extreme treble.

Hope that helps to clear up your confusion. Those articles I linked to earlier should help too.

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Re: EQ question re- size of frequency range to adjust

Postby GS1 » Sat Jun 16, 2018 2:36 pm

Much thanks to both of you for taking the time to explain this in detail- after a week of trying to figure this all out I now have a clear sense of things...and it came at the right time as I had called TASCAM yesterday and got a continued vague sense of things from the person I spoke with there,called a few Guitar Centers and spoke w people in Pro Audio/posted stuff on a few other online forums without getting the kind of clear explanation above...

Also I have begun actually working w/the EQ settings and seeing how things are actually affected,
writing down the frequency + boost/cut settings I found worked...I think my confusion about things was due to having studied a lot of online stuff about mixing/mastering w/out a clear sense of what the DP-008 can actually do i.e.

The compressor allows you to adjust ratio/threshold/amt of gain reduction dB for three bands but not the attack/release.... Still in conjunction w/the EQ (and the fact that EQ adjustments are possible during initial track recording/after rec tracks /when mastering the stereo master track mixdown )I feel I'll be able to do quite a bit in tetms of producing a professional sounding end result and then go online w/the file converted to wav.and use Audacity or something to high-pass filter it or make other fine-tune adjustments)....

Again I wanted to emphasize I am literally just getting started w/the process of using the TASCAM,up to now I had been using the 16 track sequencer on my keyboard workstation(Casio WK 6600)and the ZOOM RT223 to put tracks together which I then recorded using a liitle handheld digital voice recorder off the speakers out of the ZOOM and the keyboards speakers directly,just mixing the 2 in terms of vol level (but panning the tracks on the keyboard)and recording this mix on the external mic- not using line in or anything so -

I have 50 or so tracks on the digital handheld to use as demos to redo using the TASCAM-man what a difference in sound quality from the initial process used to make these little demos to listen to and see how what I was trying to do musically translated to actual results and the 2 tracks made using the TASCAM which I recorded using line out from the keadphone mix into the digital. ....


Hugh you seem to be familiar w/the DP-OO8ex itself and what it can do...have you spent time actually using it?
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Re: EQ question re- size of frequency range to adjust

Postby GS1 » Sat Jun 16, 2018 8:22 pm

Just noticed that while the mastering compressor doesn't allow for attack/release adjustment the input compressor presets DO !!Haven't worked w/it yet but I'm assuming that it also can be used on tracks once recorded as the EQ settings do....
Also saw the unit has "de-esser + exciter " which cut + boost respectively @ specific frequencies between 1-4k w/the amount adjustable ....

In an earlier post this week I incorrectly referred to the distance between octaves in terms of Hz as being 20,when discussing Q width...didn't realize this at the time and not sure which of the many online articles I was reading led me to think in terms of that #,being a musician w/awareness of concepts like the A's below/above A 440 being A 220/A 880 I'm surprised I didn't make the connection between this and the way I was trying to conceptualize Q...excuse me for posting incorrect info...
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Re: EQ question re- size of frequency range to adjust

Postby CS70 » Tue Jun 19, 2018 10:11 am

Hei GS1, learning is always fun!

As you're into the technicalities tough, be aware that you may incur the risk of overthinking this. Mixing is an art! As any art is founded in knowledge, but ultimately it's all about our choices - you learn the rules and then break 'em.

As Zukan says, there's no hard an fast rules on Q: in any channel eq, you start with what you need (a narrow cut to remove an annoying frequency? A broad change of tonality? Making space for other instruments?), find the respective band and if that band has a Q control you wiggle towards a rough narrowness or broadness starting from the "1" position. While you wiggle, you listen to the result. The specific decimals in the Q are largely irrelevant.

There's a couple things that follow: apart from really specific cuts to remove unwanted frequencies, or stuff like hi-passing, you usually want to EQ a track while the others are playing, so that you can find how it sounds in context, rather than alone. Certain EQed tracks will sound horrid by themselves but become perfect in the context of the mix.

For the rest of the effects - be aware that the basic of mixing is always and only the balance. Sure, when you're a bit experience there's no problem in getting say a specific timbre or feel on a vocal track and rebalance it afterwards (something that you generally may need to do after EQing, as per def you're boosting of reducing the level of certain frequencies).. but don't let yourself be trapped by the allure of putting down effects without thinking why. Unless of course you're testing! :D

Have fun!
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