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Pro-Q 2 Natural Phase - post-ringing

I have been using Pro-Q 2 almost exclusively for EQing ever since it came out, and for me it's the best workflow I've ever had in an EQ plugin, and *mostly* the best sound too...

But the one thing I've noticed is that Natural Phase mode has a very distinct post-ringing sound to it... to the point where it really creates bass weirdness in dance music (basslines, kick drums) because the post-ringing is so noticeable it can create a distracting rhythmic effect and lose a sense of tightness in the bottom end...

Zero Latency mode is, by comparison, very tight in the bass region and it's weird to A/B between the two...

Is this an intended aspect of the Natural Phase sound?


Hi Vance,

Would it be possible for you to e-mail us an audio snippet so we can listen to the difference ourselves? That would really help!

Floris (FabFilter)

Here's Pro-Q 2 on a kick drum:

Natural Phase: dl.dropboxusercontent.com/u/7988988/kickdrum_naturalphase.wav

Zero Latency: dl.dropboxusercontent.com/u/7988988/kickdrum_zerolatency.wav

Setting is:

56.749 Hz
1.225 Q

The Natural Phase setting has a sub-bass "ring" that hits noticeably *after* the transient, so you kind of have a feeling of a double-hit... Transient, then sub.

The Zero Latency version doesn't have this delay in the ringing (or the delay is short enough that it's less noticeable) and so the perception to me is that the Zero Latency setting is way more "tight".


Hi Vance,

Very interesting indeed. First of all, I analyzed the files: the Natural Phase algorithm does introduce a tiny difference, but this is taking place at a very low level below -100 dB, which should be inaudible to the human ear... This is also what I would expect. Natural Phase mostly fixed phase issues in the high frequency area, for lower frequencies it should be (almost) equal to Zero Latency.

To confirm this, I played both WAVs together but out of phase, and indeed, the difference is (practically) inaudible (at least in my simple listening environment here).

Of course, some people are definitely more sensitive to small changes in sound, but to actually hear the difference between these two files, would require supernatural hearing I think. You may of course interpret that as a compliment ;-) But it might still be interesting to to a double-blind listening test.

The basic idea of double-blind testing, is that you compare the files while not knowing which is which (actually: while no one in the room knows which file is which). Always a fun experiment and it very often proofs how much you (and I!) can be fooled.

You know what: let's do the experiment! Here's a small ZIP with 40 kick drum snippets, of which a part is actually your Natural Phase version and a part is the Zero Latency version... but they're simply named kick1 to kick40. I have made a little excel sheet of which is which. I suggest you listen to all these files one after the other and write down whether you think it's Natural Phase or Zero Latency.


Go fot it and let us know which is which; I'll ask Frederik (FabFilter) to do the same, to see how he scores ;-)


Floris (FabFilter)

Totally forgot about this! Will come back with some results soon!


I've noticed this too.. old post but I just want to add my opinion on this since i was playing about with something like this yesterday. Check out the phase response here though


, I think it has to do with that steep slope at the highest frequencies of the natural phase mode... theoretically we should't hear it but its definitely harsh compared with zero latency to my ears. Seems to add something nice to some sounds, but I avoid using it for high end.

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