FabFilter User Forum

Pro-q pitch shifting eq

Hello and thank you for this great product!

Warning: extremely long technical post with only one smiley.

I have never seen a software eq that would be able to follow pitch and "transpose" the bands accordingly. Here's a very simplified example:
you have a bassline playing the A1 note and you make a 12db cut at 82 Hz with a narrow Q and really like the way this sounds. But when the bassline switches to A2 the sound you tweaked so hard is gone. To get it to sound like before you need to make a 12db cut at 165 Hz, but now you already have 2 bands with deep cuts so when the bass switches back to A1 the sound changes again.
Or another scenario: lets say you have a a recording of a live bass and there are some very bad ringing artifacts only when playing certain notes. You could use a sharp and narrow cut to cut them out but now this effects the sound of the non-ringing notes too much. Or you could use wider cuts but that again changes the sound of the notes you don't want changed etc...

Now, if that didn't make any sense please watch this video: www.youtube.com/watch?feature=player_embedded&v=iJNutBk5N78
This is the only eq that I know of that does this (in a way) and I was very excited when I discovered it. And also very surprised that with the gazillion of software eq's that we have on the market today, no one has ever thought to add this feature. Except it is unnecessary complicated and almost never works the way it should - i.e. it uses audio to track the pitch and it is more than most of the time wrong and especially very slow when the notes change. It's especially useless for any kind of fast note plucky type synth basslines.

For myself, this feature would be very useful. Just one scenario: Choose a moogy/plucky type of bass and play a note. Now make a deep boost of 12 db or more an octave or two above the fundamental, optionally make a few additional deep cuts or boosts with a narrow Q - almost creating a comb type filter. You can experiment with the Q and the amount of boost/cut to hear some different results.
Now put a saturation or a distortion plugin after the eq. Especially multiband distortion works great with this. Now the problem here is that the sound changes drastically when you play different notes.

This is where I have an idea that I would like to pimp to the fabfilter team. Instead of using audio to track pitch (like the eq linked above) I would use midi for that.
Audio pitch tracking (realtime at least) never works the way it should (download the demo of that eq to see for yourself) and when you have chords playing or multiple octaves it just turns out to be completely useless, especially for faster note transitions or shorter note durations.

Using midi for this has 2 advantages:
1. no need to spend time programming some algos that may work in an ideal scenario - I imagine it can be done by an experienced programmer in a matter of hours if not minutes.
2. does not add any significant strain on the CPU. Audio pitch tracking certainly does.
3. Works 100% of the time with 100% accuracy! :)

Now you may think this might be useful only for synth, but this can be useful even when working with audio, you simply make a midi track with the sequence the audio is playing. Hell, you could even use something like melodyne for this if you don't feel like doing it manually.

Now, here is how I imagined this to be implemented into Pro-Q:

you insert pro-q on the track you want to eq (standard procedure), now you add a midi track that has the same midi sequence (events) on it as the track with pro-q on it. Now you just route that midi track to pro-q and you're done.
Now, you have to select a root note in pro-q. Let's say you have looped a bar of your bass line which is playing C#2 and you begin eqing it. Let's say you make two bands; one at 69.2 Hz with a 3db boost and another at 500 Hz with a 6db cut. Now if this is the sound that you want for the bass for what ever note progression it is playing you just select C#2 as the root note in pro-q and copy over the midi sequence to another midi track which is routed into pro-q. Let's say the next bar plays E2 -> Since C#2 is 69.2 Hz and you have that midi track routed to pro-q, the plugin shifts the first frequency bands by 9.6 Hz upwards and the second band by 78.8 Hz.
Meaning that our pro-q frequency bands when the bass is playing the E2 note should be at 82.2 Hz and the second one at 594.6 Hz.

I'm a math moron so maybe somebody can check if my math works out. I used this equation for this: www.phy.mtu.edu/~suits/NoteFreqCalcs.html
But anyway, you get the picture.

They say a picture is worth a thousand words, so here's everything routed and working as described and the way I'd imagine Pro-Q could implement this: i.imgur.com/FQ4KR.png

Notice that there are still some open possibilities here. I added a predelay of sorts before the shift to the next note starts to take place and portamento - how fast the shift happens. Portamento is useful if you have some very high boosts in there or a decaying sound so the shift is gradual and doesn't sound instantaneous - unnatural.

This really can't be too difficult to implement and can be highly useful in certain situations and since Fabfilter is the kind of company that doesn't make "standard" plugins I'd figured this might be something you'd give a thought and hopefully we'll see it soon.

God I hope that made some sense...
Anyways, thanks for the great plugins!


Very good suggestion ... working with automation in this kind of situations is awful.

Chris L.

haha, when i red the title i just had the idea in my mind that you want a eq where you can say select a frequency and tune it by the amount of gain (may this idea would find some friends as well) ;D ..but actually i red your whole post and can remember, that i had needed this feature in the past several times myself.. so yeah, why not implementing this in pro-q? there could also be an expert-button as in the other pro-ff plugs which opens the tune controls. would be really nice to see this :)

cheers pascal

Pascal Kulman

I normally laugh at the feature requests on this forum, such as bigger displays, better spectrum display etc, but this is a good one.

I'm all for it, big +1

cheers that man


I too have been after an eq that can do this for some time. It would be nice to see the Volcano 2 modulation options in Pro Q, but for now I've recently discovered the 'Mfilter' eq at meldaproduction.com. This can track pitch through audio input or midi input. It also has many other modulation options, and is very cheap to buy. Also if you use Reaper you can use parameter modulation to link Pro Q to Mfilter so Pro Q now tracks pich or any other modulation of Mfilter. Awesome stuff indeed!


the Sound Radix SurferEQ basically does this by having every band and filter track the pitch of the note and moves them accordingly including several other algos. Would be great to see this kind of feature in all modern EQs honestly.


Yes, but it's not possible to send midi notes to it if you so desire.



Thanks for the detailed suggestion. I certainly see how it could be useful, although I think it might be challenging to implement it in a way that makes it easy to understand. But that's why we're here of course. :-)

We'll consider it for a future Pro-Q update.

How do you think chords in the MIDI data should be handled? Use the highest note, or average?


Frederik (FabFilter)

what about a menu with the options of highest, average, or lowest?

I'm picturing this via a sliding external section ala pro-c's expert mode, or pro-l's advanced tab.

I know that's probably 3x the work but it would suit about every occasion.


any news on that ?
Is SurferEQ really the only who got this feature?

pling plong

Excellent suggestion!

Maybe this can be achieved by adding a modulation section to Pro-Q 3. With XLFO, Envelope Follower ect. and the MIDI input option you are talking about.

Sine wave

We didn't want to complicate Pro-Q 2 by adding a complete modulation section.


Frederik (FabFilter)

How is this any different from adding keytracking to the center frequency?

Mr. Pro-L 1

key tracking sounds good to me, I think having the frequencies controlled by a midi track should do the trick.


Could 'note number' just be another parameter that activates MIDI learn? i.e. Click MIDI lean, click the band frequency, start playing the keyboard & it begins to track ?


@11235 That reads like the MIDI trigger option in the XLFO modulation panel for their FX plugins.

Mr. Pro-L 1

Great idea


i would def switch from equilibrium if this happened.

money bags

This guy did this in the fruity parametric eq2 in fl studios.


@Frederik (FabFilter) would love to see this on a pro Q3


Hey folks,

This is easily achievable using the MEqualizer from Melda Productions. It has a modulation subsystem with which you can track the freq of the EQ (as many bands as you like) up and down your keyboard.


Hi team! Hey is there any plans to include similar feature as www.soundradix.com/products/surfer-eq is offering currently? This type of functionality would be highly useful.


We'll look into it for a future version!


Frederik (FabFilter)
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