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Phase Linear EQ with no pre ringing?
Old 29th November 2018
  #61
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I did some more testing.

At first I tested the zero phase in pro-Q3 vs linear phase (high). This is quite easy to A/B blind with 100%.

But zero phase in pro-Q3 vs linear phase (low) isn't as obvious. I get only a 40%/60% rate.
Old 3rd December 2018 | Show parent
  #62
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Quote:
Originally Posted by AreYouHuman ➡️
So far I never used linear phase on individual tracks as low latency also better fits to my workflow.

But I just tried the new fabfilter pro-q3 for fun. I tried the same setting with zero phase and linear on hihats. So only a mid and high range test! I can't stand pre-ringing on the bass.

The linear phase sounds indeed a bit tighter and with better room. I can a/b it blind without a problem on headphones. But maybe the pro-q3 has just a mediocre zero phase implementation? Who knows.

My setting were bell/12db at 4300hz, 7.6db gain, Q 1.

But I also almost blindly trust FabienTDR opinion when it comes to technical explanations.

Not sure what this means for me now.
you should still try on one band removing some mud, sometimes it can be more transparent with linear phase, you might get pre ringing as low as the noise floor..it might still be earable thought.
Personally i rarely use Lp cause of the latency and cpu, even if sometimes it can sound better .. but to me the most transparent eqs, can only be one that let you adjust the amount of pre ringing to the point it s not a problem for the band used , so using a eq that let you adjust the amount of phase shift between lp and phase.

just do what sound best to you and don t care about technical, the less you know about technical aspect the more you trust your ears and the less you re victim to placebo , evrything your ear is first filtered by your brain and then your judgement come of what you heard, the less you know the less it s filtered i guess.

Last edited by Fred_Abstract; 3rd December 2018 at 11:47 PM..
Old 5th December 2018 | Show parent
  #63
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in pop music, i cannot see much use for fir filters: sometimes, deliberately introduced phase shifts are getting used to widen the picture and there are way too many things going on (hundrets of tracks, efx etc.- just watch your phase meters while mixing).

for classical music, for mastering and for aligning speaker systems, there is some benefit (besides the typical issues)...
Old 5th December 2018
  #64
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Linear phase EQ and stereo phase are completely unrelated concepts.
Old 5th December 2018 | Show parent
  #65
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i'm not talking about phase correlation (which is an issue in at least two of the fields i mentioned), i'm talking about how useful it is to use linear phase filters in different areas/genre...
Old 5th December 2018 | Show parent
  #66
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Quote:
Originally Posted by deedeeyeah ➡️
in pop music, i cannot see much use for fir filters: sometimes, deliberately introduced phase shifts are getting used to widen the picture and there are way too many things going on (hundrets of tracks, efx etc.- just watch your phase meters while mixing).
Allow me a pedantic comment:

FIR is just a filter structure. The most precise filter structure known to humanity.
It can cover everything you want, given sufficient CPU power.

Directly equivalent are so called "real-time FFT" filtering structures. They are equal to FIR, but from a frequency domain perspective (FIR follows the time domain perspective).

The main practical difference is about CPU performance and latency. FIR have lowest latency, but bad calculation complexity. Small IRs are rather fast, but everything beyond ~1000 taps will likely create trouble.

Real time FFT on the other hand imposes a fixed latency and limited precision directly depending of the size of the FFT block (it defines the maximum size of the IR).

Qualitatively, both are equal. Both can theoretically run almost any IR you like. This IR can be linear phase, min phase, or anything between. FIR (and realtime FFT) always have a finite IR length, though.

An IIR on the other hand is a recursive structure (it feeds-back previous values to eternity), so it naturally only supports IRs that are infinite in nature. They accumulate errors, and thus need very precise internal number representation (64bit). Fast like a lightning, but the range of possible IRs is somewhat limited.

Good overview:
Filter Classification

Last edited by FabienTDR; 6th December 2018 at 01:37 AM..
Old 5th December 2018 | Show parent
  #67
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🎧 5 years
Quote:
Originally Posted by Greg Reierson ➡️
Linear phase EQ and stereo phase are completely unrelated concepts.
How is it so? If I do minimum phase with mid or side low cuts for example, it does changes to what sounds in left and what sounds in right, the stereo picture is lost, all panned elements are in wrong places. Linear phase does nothing to stereo. Check this on masters with panned left/right elements. Try equailibrium.
Old 5th December 2018 | Show parent
  #68
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Quote:
Originally Posted by FabienTDR ➡️
Allow me a pedantic comment:

FIR is just a filter structure. The most precise filter structure know to humanity.
It can cover everything you want, given sufficient CPU power.

Directly equivalent are so called "real-time FFT" filtering structures. They are equal to FIR, but from a frequency domain perspective (FIR follows the time domain perspective).

The main practical difference is about CPU performance and latency. FIR have lowest latency, but bad calculation complexity. Small IRs are rather fast, but everything beyond ~1000 taps will likely create trouble.

Real time FFT on the other hand imposes a fixed latency and limited precision directly depending of the size of the FFT block (it defines the maximum size of the IR).

Qualitatively, both are equal. Both can theoretically run almost any IR you like. This IR can be linear phase, min phase, or anything between. FIR (and realtime FFT) always have a finite IR length, though.

An IIR on the other hand is a recursive structure (it feeds-back previous values to eternity), so it naturally only supports IRs that are infinite in nature. They accumulate errors, and thus need very precise internal number representation (64bit). Fast like a lightning, but the range of possible IRs is somewhat limited.

Good overview:
Filter Classification
thx fabien, spot on (as always) - i should not have used technical terms (and confusing definitions) but should have put it in much more simple terms (see below). also, i noticed too late that this thread is in the mastering forum... - i should not post minutes before a gig!



[it should have been something like that:
imo it's not worth going the extra mile (and chose specific filters) if things get mixed/'messed up' anyway (in a pleasant way though) - but one could also argue that in exactly this situation one should better use the 'best'/most appropriate filters...]
Old 5th December 2018 | Show parent
  #69
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Quote:
Originally Posted by Stereo Flux ➡️
How is it so? If I do minimum phase with mid or side low cuts for example, it does changes to what sounds in left and what sounds in right, the stereo picture is lost, all panned elements are in wrong places. Linear phase does nothing to stereo. Check this on masters with panned left/right elements. Try equailibrium.
This is bit special case with unlinked M/S EQ.

Choice of min-phase or lin-phase EQ doesn't directly affect stereo picture per se (in the sense of narrowing it besides applied correction itself or steering it towards one side, change position etc.)
Stereo information in M/S system is carried solely by difference (S) channel.
So when you apply some minimum phase filter to S, then of course you'd introduce respective phase shift there, but that shift is then affecting both decoded L and R channels by the same amount.

M/S decoding matrix is like this:
L = M + S * atten. factor
R = M - S * atten. factor

Of course when you combine M/S channels like that in the decoder and one of them is phase shifted, it will affect your outcome and there might be certain perceived difference in sound. Some cancellation or boost will occur according to the shift.. say you might feel loosing overal definition with some filtering, possibly you'd need slightly alter the filter settings to achieve similar apparent results, when comparing lin-phase and min-phase. But the shift won't be different among L and R output channels, so stereo information is not directly affected by that.

Finally, the choice of used filter type (min or lin) might be totally subjective and material dependent.. but it's the same like with other cases (not isolated to unlinked M/S) and IMO it's not possible to say for example, that lin phase is not suited for the task as it affects stereo image.

Michal
Old 5th December 2018
  #70
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And another comment.. to what deedeeyeah mentioned before.
I don't think, that lin-phase filters would be more useful for say classical than pop or say audio for video post production. From my experience, it's also useful always, when you benefit from preserved phase coherence between tracks or channels regardless of genre.
This might involve treatment of multi miked sources, parallel FX chains.. etc. With regards to latter for example it's very common to use additional filtering to band-limit or shape some parallel chain (with heavy compression, distortion) to be blended with original. Quite often it's really significant difference to use lin-phase EQ there, especially with transient heavy material, where it's rather apparent. Also built-in filters at vast majority of saturators are minimum phase, so it might be worth of shot to bypass it and use another EQ there.

Of course, it's always about balancing of benefits and tradeoffs, so easy comparison is big plus. So I personally really appreciated modern EQ plugins (Pro-Q, Equilibrium, LP10) with easily switchable operating modes with few clicks and lightweight operation, if you don't need long FFTs for increased low frequency resolution. Those have also common preserved magnitude response (that was quite annoying at some older plugins, which has different responses in min or lin mode).
It's a quite significant reason, why I won't be happy to use just dedicated lin phase plugin without chance to switch it to normal mode.

Michal
Old 12th January 2019
  #71
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🎧 5 years
from this post:

MAAT thEQorange

Friedemann T
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Joined: May 2009
Location: Cologne Germany
Posts: 14

MAAT thEQorange
Dear Mastering and Audio Engineers,

I am Friedemann Tischmeyer, mastering engineer and the founder of MAAT.digital. We at MAAT had a misleading communication and I would like to shed some light on this and excuse for that.

Reissuing the gorgeous Algorithmix tools is one of the many reasons why I founded MAAT. I have used the Algorithmix LP PEQ Orange alongside other Algorithmix tools on a daily basis for more than 15 years. On more than 1000 of my releases, it became an essential tool in my mastering chain. Long before I started MAAT, I searched around on the EQ plug-in market to find a replacement due to the many requests of my students asking for gear recommendations. I couldn’t find an alternative, which is why we went on this long journey to re-issue the Orange EQ in a new look and with new functions to make it even better.

The reason why thEQorange is so special for me is its ability to sound “correct” and natural when I remove resonances and clean up the lower midrange when compared to other EQs.
Suddenly the mix seems to appear lighter and comes out from the loudspeakers with more ease so that it gets ready for subsequent treatments which I do either with the PEQ Red or my analog mastering chain.

However, I always looked on that project from my passionate audiophile user point of view rather than a pure technical or analytic view. I have actually no clue why it is the case that thEQorange sounds different from other surgical LP EQs used for such tasks. I was wondering about it but not asking for the reason as I am no DSP guru anyway. And here comes the accident: Due to a very high workload in my new studio with an 80h working week in a mix with crazy stuff happening in my private life, I didn’t get the opportunity to work with Oliver to prepare the campaign for thEQorange release. Despite it being my responsibility as the CEO of MAAT to approve all information used before release, I simply didn´t find the spare time for this which in turn caused the publication of misleading technical information regarding the pre-ringing behavior of thEQorange. “No pre-ringing” is basically bull****, please excuse us for the release of this wrong information.

My dear colleague Bob Katz asked me to look deeper into this and finally I found some time within the last two weeks to investigate the technical aspects of the EQ design with the help of Dr. Hatje (the DSP programmer) and Dr. Musialik (the DSP algorithm architect). It gave me a full picture of the facts: thEQorange is a forward/backward-based linear-phase EQ and it does have pre-ringing by definition, like every linear-phase equalizer. “Why it sounds to me better than any other linear-phase EQ I tested so far?” I asked the experts. The reason for that might be the chosen method of implementing linear-phase filters, the refined signal windowing, the extreme accuracy of calculations, consideration of psychoacoustics … probably a great combination of all. The development and optimization of details for the Orange algorithm took many months of intensive mathematical simulations, programming, and audio tests.

Both of us, Oliver and I, hate misleading marketing messages which can be found throughout the world of audio too often and - as I love MAAT, and what we do and will continue doing in the future - I promise that such an error will never happen again.

One final thought may be allowed: I purchased the Algorithmix PEQ Orange for crazy sum of €1,200 back in the day and every penny was worth it. The current price of $990 is also at a premium but it´s definitely still worth every penny. As a licensee of the original code, we are bound to royalty agreements and the specialists involved into this project are top scale professionals. A surgical EQ is a tool, mastering engineers spend usually more setup time on than with any other tool in their chain. I am very happy with the outcome, as the new UI makes it faster and easier to set up. Now, thEQorange also saves my time while improving the sound quality. And even if it saves only a few minutes for every song, thEQorange pays for itself pretty fast.

Anyways, thEQorange is a specialized tool for pros who want to make a difference, and despite other companies having devaluated the perception of the value of software, we think that everybody has the freedom of choice to drive a Fiat or a Ferrari or -- to use another metaphor -- every wine drinker has the free choice between Trader Joe’s or a Haut Médoc.

Once again, sorry for creating confusion! And cheers with a good wine :-)

Friedemann Tischmeyer
Old 12th January 2019
  #72
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Slightly relevant to this discussion, a couple of recent vids from Dan Worrell:

YouTube

YouTube
Old 12th January 2019
  #73
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Dan
Old 28th January 2019
  #74
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🎧 5 years
Old 12th February 2019
  #75
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I just skipped through this discussion (unfortunately only in german):
YouTube

where MAAT owner Friedemann Tischmeyers answers some questions about the Orange EQ. The "no pre ringing" promise could not be kept, sadly, but not unsurprising.
So still no revolution in digital EQ in sight...
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