Short answer: one octave is Q 1.999 (or 2.0 if you will) on FabFilter Pro-Q.
Otherwise, let's get into this in detail. So the quality factors that you see in the first column below are what you'd use on most digital equalizers, e.g. iZotope's Ozone Equalizer, Neutron Equalizer, DMG Equality, DMG Equilibrium, PreSonus Pro EQ, MAAT thEQblue (i.e. Const-Q New), etc.
But that isn't the same on FabFilter Pro-Q (the third column below), Waves Q10, Softube Weiss EQ1, Softube Weiss EQ MP, etc because they all implement a different approach even though you can get similar results as far as the width of the curves is concerned assuming the EQ plug-in in question doesn't cramp i.e. phase and amplitude wrapping when using high-frequency bells.
Furthermore, not all EQs have symmetrical curves (this is self-explanatory: I am not going to waste time expagorating this) and most digital equalizers don't go beyond 4 ¾ octaves (i.e. quality factor 0.200217) as much as FabFilter Pro-Q.
And notwithstanding the aforementioned, it makes real sense not to exceed more than 4 octaves either when mixing or mastering music. But then again what's wrong with providing that option for all the experimental enthusiasts out there who think they know better? Experience is the best teacher after all—they can always learn from it.
Quality factor | Number of octaves | FabFilter Pro-Q |
---|
0.017544 | 11 ⅔ | 0.025 <!-- that's insane --> |
0.018588 | 11 ½ | 0.026 |
0.019694 | 11 ⅓ | 0.028 |
0.020271 | 11 ¼ | 0.029 |
0.022108 | 11 | 0.031 <!-- eleven octaves --> |
0.024111 | 10 ¾ | 0.034 |
0.024818 | 10 ⅔ | 0.035 |
0.026296 | 10 ½ | 0.037 |
0.027862 | 10 ⅓ | 0.039 |
0.02868 | 10 ¼ | 0.041 |
0.031281 | 10 | 0.044 <!-- ten octaves --> |
0.034118 | 9 ¾ | 0.048 |
0.03512 | 9 ⅔ | 0.049 |
0.037214 | 9 ½ | 0.053 |
0.039434 | 9 ⅓ | 0.056 |
0.040593 | 9 ¼ | 0.057 |
0.044281 | 9 | 0.063 <!-- nine octaves --> |
0.048306 | 8 ¾ | 0.068 |
0.049729 | 8 ⅔ | 0.070 |
0.052702 | 8 ½ | 0.075 |
0.055854 | 8 ⅓ | 0.079 |
0.057502 | 8 ¼ | 0.081 |
0.062745 | 8 | 0.089 <!-- eight octaves --> |
0.068475 | 7 ¾ | 0.097 |
0.070501 | 7 ⅔ | 0.100 |
0.074738 | 7 ½ | 0.106 |
0.079236 | 7 ⅓ | 0.112 |
0.081588 | 7 ¼ | 0.115 |
0.089084 | 7 | 0.126 <!-- seven octaves --> |
0.097292 | 6 ¾ | 0.138 |
0.100199 | 6 ⅔ | 0.142 |
0.106286 | 6 ½ | 0.150 |
0.112761 | 6 ⅓ | 0.159 |
0.116152 | 6 ¼ | 0.164 |
0.126984 | 6 | 0.180 <!-- six octaves --> |
0.138894 | 5 ¾ | 0.196 |
0.143125 | 5 ⅔ | 0.202 |
0.15201 | 5 ½ | 0.215 |
0.161496 | 5 ⅓ | 0.228 |
0.16648 | 5 ¼ | 0.235 |
0.182479 | 5 | 0.258 <!-- five octaves --> |
0.200217 | 4 ¾ | 0.283 |
0.206558 | 4 ⅔ | 0.292 |
0.219944 | 4 ½ | 0.311 |
0.23435 | 4 ⅓ | 0.331 |
0.241968 | 4 ¼ | 0.342 |
0.266667 | 4 | 0.377 <!-- four octaves --> |
0.294517 | 3 ¾ | 0.417 |
0.304601 | 3 ⅔ | 0.431 |
0.326128 | 3 ½ | 0.461 |
0.349672 | 3 ⅓ | 0.495 |
0.362291 | 3 ¼ | 0.512 |
0.404061 | 3 | 0.571 <!-- three octaves --> |
0.452873 | 2 ¾ | 0.640 |
0.471034 | 2 ⅔ | 0.666 |
0.510734 | 2 ½ | 0.722 |
0.555718 | 2 ⅓ | 0.786 |
0.580547 | 2 ¼ | 0.821 |
0.666667 | 2 | 0.943 <!-- two octaves --> |
0.775943 | 1 ¾ | 1.097 |
0.819292 | 1 ⅔ | 1.157 |
0.919803 | 1 ½ | 1.301 |
1.044451 | 1 ⅓ | 1.477 |
1.11883 | 1 ¼ | 1.582 |
1.414214 | 1 | 2.000<!-- one octave --> |
1.902102 | ¾ | 2.670 |
2.144908 | ⅔ | 3.033 |
2.871 | ½ | 4.060 |
4.318473 | ⅓ | 6.107 <!-- third octave --> |
5.763566 | ¼ | 8.151 |
7.207702 | ⅕ | 10.19 |
8.651359 | ⅙ | 12.24 <!-- narrow --> |
11.537951 | ⅛ | 16.32 <!-- surgical --> |
14.424063 | ⅒ | 20.40 |
17.309934 | 1⁄12 | 24.48 |
23.081316 | 1⁄16 | 32.64 |
28.852457 | 1⁄20 | 40.00 <!-- that's insane --> |
As you can see from the table above, one octave on FabFilter Pro-Q = 2.000 whereas if you are using say, for example, iZotope Ozone/Neutron Equalizer you'd set it to Q 1.41 and you'd do the same to PreSonus Pro EQ, etc.
Otherwise, this is probably what gets most people confused because they think all digital EQ parameters can literarily be set to the same values but in reality, you won't get matching results if that's the primary objective.
Additional FF Pro-Q tips, hints, and tricks
Perhaps you may want to seriously consider the idea of routinely making use of the following quality factors either for
audio mixing or mastering. Doing so will not only allow you to work faster but it's essential if you want to come up with a very consistent sound (i.e. efficiency, calculability, predictability, and control):
Subjective Label | Number of octaves | FabFilter Pro-Q |
---|
Wide | 3 ⅔ | 0.431 |
Broad | 3 | 0.571 |
Blunt | 2 | 1.000 |
Gentle | 1 ⅓ | 1.477 |
Sharp | 1 | 2.000 |
Acute | ⅓ | 6.107 |
Narrow | ⅙ | 12.24 |
Surgical | ⅛ | 16.32 |
Q 0.571 is best for tonal shaping especially in the upper midrange i.e. starting from 1.6 kHz and going all the way up to 20 kHz.
However, you could also use Q 0.571 for bottom lifts e.g. at either 50 Hz, 80 Hz, or 130 Hz instead of using a first-order low-shelving filter (i.e. 6 dB/octave slope) because bell curves gradually roll off without raising additional rumble, unlike shelving filters that remain flat once they reach the amplitude they are set to.
But in most cases, Q 1.00 or Q 1.477 are also suitable in that area or even 2.00 (which is one octave) particularly to bring up a kick drum and make it knock harder without making the entire mix too boomy than it should.
You can use the table below as a general reference guide depending on how you are trying to implement bottom lifts with a bell of Q 0.571
Bottom wide bell Q 0.571 | First-order filter |
---|
@130 Hz | Approx. @ 320 Hz |
@ 80 Hz | Approx. @ 200 Hz |
@ 50 Hz | Approx. @ 130 Hz |
@ 30 Hz | Approx. @ 80 Hz |
N.B., a major flaw with a Q of 0.571 (i.e., 3 octaves) on the low end is that it is too wide for most mastering applications (unless you are dealing with a very thin-sounding mix which is very rare because most mastering issues are either too much bass, muddy low-mids 200-500, and bloody piercing high frequencies from 6.5k to 10k).
If you may want to use a nice wide Q 0.571 to add shimmer, sheen, air, presence, focus, or more midrange clarity. Check out the table below as a reference point:
Top wide bell Q 0.571 | First-order filter |
---|
@ 30k | Approx. @ 12.5k |
@ 24k | Approx. @ 9.5k |
@ 17.5k | Approx. @ 6.5k |
@ 10k | Approx. @ 3.5k |
@ 6.5k | Approx. @ 2.4k |
@ 5k | Approx. @ 2.0k |
@ 3.5k <!-- pressure point for loudness wars --> | Approx. @ 1.4k |
@ 1.6k <!-- midrange clarity, use Q 0.821 as an alternative --> | Approx. @ 620 |
Now suppose you want to make your graphic equalizer with Pro-Q, well, that's a very simple thing to do actually, except the problem with making your graphic equalizer is deciding what quality factor is most useful for both mixing and mastering applications.
With that said, I'd recommend Q 0.821 including using
fixed center frequencies once suggested by
@Scorpio and these are:
- Band I = 20, 30
- Band II = 40, 50
- Band III = 80, 130
- Band IV = 200, 300
- Band V = 500, 800
- Band VI =1.2k, 1.6k
- Band VII = 2k, 3.5k
- Band VIII = 5k, 6.5k
- Band IX = 8k, 10k
- Band X = 12.5k, 15k
- Band XI = 17.5k, 20k
- Band XII = 22k, 24k
The reason for using Q 1.00 is that it's not too wide nor is it too gentle. It's only 2 octaves and that's a lovely thing. An alternative solution is Q 0.943 (i.e. precisely 2 octaves) but not Q 0.571 neither Q 2.000 nor Q 6.107 because those quality factors just ain't got that bandwidth sauce for a smooth musical graphic equalizer. They are terrible in this context, m'kay!