SAC eq width and real Q factor.

[martiaudio]

Could it be possible to come up with a graph of SAC eq width value corresponding to real Q factor.
it is reversed: the higher the Q factor the sharper the peak. and visa versa..

but it isn't a linear, clean log or exp.. it is different.

To my mind in order to better understand the sac and SAW eq width parameter i need to picture the Q factor of a real eq if it makes sence.
thank you.

[sebastiandybing]

I found a bw to q converter for the iphone
0.1 octave is q=14.4
1 octave is q=1.41
3 octaves is q=0.4

Sebastian

[sebastiandybing]

To me the bw. in octaves is a much more
musical way of showing the bw.
You could sit at a piano and play with
the bandwith, like 0.1 is more or less one
key on the keyboard and 1 octave is c to c
if your taget key is f# and so on.

[Cary B. Cornett]

To my mind in order to better understand the sac and SAW eq width parameter i need to picture the Q factor of a real eq if it makes sence.
thank you.
The numbers for EQ band "sharpness" in SAW/SAC show bandwidth in octaves, which is much easier to mentally picture than "Q". It isn't difficult at all, because it relates directly in musical terms.

What might be confusing is relating "octaves" to "Hertz" (cycles per second for us old guys). But even here, the math ain't rocket science. Going up one octave is the same as doubling frequency. Going down an octave is the same as halving frequency. That means a factor or divisor of 2.
For half an octave, the factor is the square root of 2, or about 1.414.
For a third of an octave, the cube root of two,
for a quarter of an octave, the 4th root of two, and so on.
If you really need to hash the numbers, grab a scientific calculator.

The same numbers apply whether it is a "real" hardware EQ or a software EQ. I have always seen the bandwidths of bands of a graphic eq, for example, specified in octaves. We've all seen those 1/3 octave graphic EQ's with 31 bands.

Some shades for SAW/SAC do incorrectly label the width parameter of the EQ as "Q", when it should really say "Oct." or maybe "BW". Perhaps that is the source of your confusion.

[dasbin]

It would be really, really nice to have an option to switch to use regular Q settings instead. I get the logic behind using octaves, but I'm so used to working with Q that my brain registers what's going on faster.

[martiaudio]

i am so used to q factor to so I can really try to emulate manually harware vintage gears..
But I am really sorry I should i've read a little before posting this question: I didn't know 2 things..
the bw is in octave..
and the equation I am after is really easy therefore..
thanks everyone.

[Bob L]

Should be no translation needed... bandwidth is very simple... if your center frequency is 1000... the affected range of the eq boost or cut will be from 500 to 2000... just take half of the center freq and double the center freq.

Bob L

[martiaudio]

something perhaps interesting:
http://www.sengpielaudio.com/ZusammenhangBandbreiteGuetefaktor.pdf
http://www.sengpielaudio.com/calculator-bandwidth.htm

[Bob L]

Q factors seem to have no relationship to music and basic audio... bandwidth is so much easier to relate to as far as I am concerned... that's why I chose it... I actually hated consoles that use Q factors whenever I had to use one on the job.

There is no right and wrong... good or bad... just preference.

Bob L

[gdougherty]

Should be no translation needed... bandwidth is very simple... if your center frequency is 1000... the affected range of the eq boost or cut will be from 500 to 2000... just take half of the center freq and double the center freq.

Bob L
This is on a 1 octave bandwidth I'm assuming? Always wondered whether it was a 1 octave end-to-end or 1 octave either side of the center frequency.

[Bob L]

On either side, if I remember correctly.

Bob L

[gdougherty]

http://www.astralsound.com/parametric_eq.htm

If they're right it's end-to-end and even more complicated as the cut/boost is increased. Interesting.

[TomyN]

Hi,

I experienced that this kind of stuff is not so easy to handle when I was programming the virtual EQ section of SATlive. One Problem is that a lot of definitions relate to -3dB, so they fail when you apply just 2 dB of cut or boost.

The label BW is not correctly used all over the audio-industry, because BW is simply fo - fu, which means it's a frequency value. The value you find labeled BW on (almost) any audio gear is 1/Q.

Oposite to that, the ocave definition works quite well.

Tomy

[airickess]

On either side, if I remember correctly.

Bob LSo then it's really two octaves that are affected when the EQ is set to 1.0 octaves.

[TomyN]

As far as I remember the value in SAC correlates very well with SATlive, which points to 1 -> one octave total.

Tomy

[JLepore]

It all depends if you are talking about a traditional analog EQ emulation ("Standard") or a "Constant Q" eq (mostly digital, but RANE used to make some analog versions).

Under a "standard" version, the Q was actually wider at lower attenuations, and narrowed as you increased attentuation. In "constant Q" - it did as the name would apply --- no matter how much cut/boost, the Q would always stay constant.

Which formula Bob used, either he can tell, or you can measure with a RTA and pink noise source.

[martiaudio]

I am still starting on sac and saw really and although I never analysed anything on M7 or LS9 couldn't see the point..
I find that I need to grasp what the SAC eq width really does.
My experience with analog and digital preamp and eq tells me that with a good and creative understanding of your digital eq tool, it is possible to emulate and save all sort of preset.. you don't need the waves eq clone for that.
But it is very important to understand hardware gears..with trying to forget any logic first and admit what they do. that is where the magic start.

Personally I am really fond of my Quadeight preamp, quadeight 712 that I made and Klark Tecknik DN27 which is a great great graphic eq the best ever made with 27 bands.. and the DN22 2x11bands..
Because I developped and made some hardware gear I have a better feeling with understanding Q. Admittelly it isn't musical at all.. it is math, guess hit and miss and lucky finding..
For exemple the q8 712 has a unregular Q of 2 which is part of its magic and previous versions well used by motown production. an interesting 7 bands graphic that could be replicated on SAC.. or SAC plugins studio graphic eq.

So It is very good to read all your views.
I will point that I am discovering the studio Frequency analyser which is great and good to test and confirm what I am doing with the SAC paramatric EQ back and forth..

I already have way too many plugins that used to be on MAC protools..
However I am starting to realise that it causes trouble it complicates things and a good understanding of SAC and SAW channel strip or so called Wide mixer can just be enough and therefore trouble free.
I like that.. I like the potential without the fancy graphic design in those expensive plugins..
I like that it is all about sound like it use to be.

[gdougherty]

I am still starting on sac and saw really and although I never analysed anything on M7 or LS9 couldn't see the point..
I find that I need to grasp what the SAC eq width really does.
My experience with analog and digital preamp and eq tells me that with a good and creative understanding of your digital eq tool, it is possible to emulate and save all sort of preset.. you don't need the waves eq clone for that.
But it is very important to understand hardware gears..with trying to forget any logic first and admit what they do. that is where the magic start.

Personally I am really fond of my Quadeight preamp, quadeight 712 that I made and Klark Tecknik DN27 which is a great great graphic eq the best ever made with 27 bands.. and the DN22 2x11bands..
Because I developped and made some hardware gear I have a better feeling with understanding Q. Admittelly it isn't musical at all.. it is math, guess hit and miss and lucky finding..
For exemple the q8 712 has a unregular Q of 2 which is part of its magic and previous versions well used by motown production. an interesting 7 bands graphic that could be replicated on SAC.. or SAC plugins studio graphic eq.

So It is very good to read all your views.
I will point that I am discovering the studio Frequency analyser which is great and good to test and confirm what I am doing with the SAC paramatric EQ back and forth..

I already have way too many plugins that used to be on MAC protools..
However I am starting to realise that it causes trouble it complicates things and a good understanding of SAC and SAW channel strip or so called Wide mixer can just be enough and therefore trouble free.
I like that.. I like the potential without the fancy graphic design in those expensive plugins..
I like that it is all about sound like it use to be.
The usefulness of the channel strip processing is why I don't use quite as many plugins. I tend to use them for special features in places where there isn't processing built-in. Plugins have to be recalled, managed, unburied where everything else is at your fingertips. I like the ability, but I find it just as annoying on the Digidesign venue boards. The waves mixrack is the only thing that really seems to have it right when it comes to plugin management for live use in regards to outboard rack style monitoring.

[RBIngraham]

Doesn't anyone just use their ears anymore?

[sebastiandybing]

Well said, but I do undestand that it is nice to
know the thoughts behind a design, one will
use for years.
Sebastian