EQ: Linear Phase vs Minimum Phase

Dan Worrall explains when and how to use linear-phase EQ'ing and normal minimum-phase EQ'ing. After discussing the general concept of phase, Dan shows some real-life mixing examples where the difference between linear- and minimum phase processing is apparent.
Want to learn more about linear-phase processing with FabFilter Pro-Q? Check out the online help topic: www.fabfilter.c...
FabFilter Pro-Q and other plug-ins are available via www.fabfilter.c... , and free 30-day trials van be downloaded from www.fabfilter.c... .

[@tomaszmazurek64]

10 years later still the best video on the subject.

[@FunkZzzz]

This is why FabFilter are my favourite plugin manufacturers. A lot of manufacturers just push on you a new plugin becase "you need this to make the mix sound awesome!" - Waves being a good example (not that Waves plugins are bad). FabFilter realises that it's not only about the tools you use, but how you use them, and they even actively try to educate you FOR FREE! Never stop making awesome plugins and awesome instructional videos!

[@NinjaDeathTeddy]

I wish this guy could sit next to me as I make music and educate me with his soothing voice.

[@aerodynechambers]

i feel like i wouldnt get anything done that way!😂

[@javilaroid]

@SOUL SEEKER HAHAHHA a good one

[@thelastaesthete]

That's gay as fuck

[@charliechimp6917]

We can teach an ai based on all his shared knowledge then use the ai to teach us

[@SheikRonMC]

Lmao

[@adriendelasalle8981]

Watching this for free is unbelievable ... Dan Worrall and FabFilter you guys are the best!

[@azimsonawalla]

Wow, solid software AND great instructional videos? Fabfilter, you guys continue to impress me... well done!

[@uszeyboi]

Now that is a technically well made tutorial. Not lile this stuff from other audio companies that just say "hey, just hi pass that, low pass that, here boost this and viola, now you know everything about eq". Thumbs up, guys.

[@hazybrain7]

Really excellent and best explanation I've come across about EQ phase. I'm shocked at how much the low and high pass filters warp the phase around the cutoff frequency. I'll treasure this information ! Many thanks to fabfilter for this free video. I'd love to see Dan Worrall do an in depth mixing tutorial, I'd pay good money for that, what a pro....

[@xaosnox]

Agreed! I'd do anything to learn at the feet of the master! FabFilter made an excellent choice by choosing Dan to present their plugins. No one else could properly demonstrate all of their amazing features. So simple, yet so powerful in the hands of someone like Dan.

[@DjangoFlaherty]

My goodness! Parallel processing just got a whole lot more confusing.

[@vasudevmaheshwari1210]

who's here from IN THE MIX???

[@audiobackdrops18]

Maybe I’m not as smart as I thought I was cause I learned nothing. Or maybe I’m deaf. 🤷🏾‍♂️

[@DROPIt7]

this is probably the greatest tutorial video of a software company i've ever seen! it's really useful information instead of telling us how awesome your product is like many other plugin manufacturers do! thanks!

[@michaelknead]

the science of EQing... thank you so much! After watching all of this the question is now: why can't the Pro Q show us what's really happening? It would be super cool to have these Analyzer slopes drawn into the Pro Q interface - this could avoid these "wtf is going on" situations :)

[@bitflux2]

no wonder its so damn hard to get professional results in music engineering : (

[@osahenipaulamenordia3321]

I swear

[@stickwithit]

Thanks future me

[@amonchhetri1053]

@@stickwithit have u dont yet?

[@dlrss1v274]

your name explains it in a concise manner

[@nicholastovarek6534]

17 Waves employees disliked this.

[@FunkZzzz]

lol

[@adithyasatheesh127]

Fabfilter is such a lucky company to be able to have Brains like Dan Worrall's speak with and for them.

[@AudioReplica2023]

im sorry but this video now confused me so hard about dealing with phase response and eq. wtf. ok this is what is confusing me, every time he`s talking about minimum phase the Pro Q is set to the feature of "zero latency" but there is another feature thats called " minimum phase " so what in reality is he talking about ? is he referring to zero latency when ever he's talking about minimum phase or the video is not in the same page of the dialog ?

[@Rakoah]

Thanks for englightening me on linear vs minimum phase.. I honestly never knew about this before. Thank you so much and thank you for providing us with the absolute best EQ on the market. FabFilter is an absolute must for my mixes!

[@alzahraniabdulrahman]

Most of people commenting about Dan , i will tell you the truth, i did’t understand anything. He should provide step by step solution and not jumping from topic to another.

[@DennisWilliamsDJ]

I have seen a lot of tutorials, and I rarely comment on videos's on KZbin, but this one is one of the best tutorials I've seen. Good speaking voice that's pleasing to the ears, not too much going on on the screen so it's quite relaxing, and a perfect balance between the theoretic part and the practical side of it. And most important; it's so complete that I don't have any questions anymore. Since I tend to watch videos on a topic until I know for sure I've covered all the significant aspects, this is a time saver ;) Dan Worrall you're my hero of the week, and I thank you.

[@Stuart.Branson.]

If I put any kind of Low Freq - EQ, filter or compressor on my master out it creates a kind of doubling effect on all low frequencies, so a Kik drum for example sounds like a double hit instead of 1 clear hit. Is this the reason ? I thought it was a bug. I have cubase pro 8.5

[@xaosnox]

Dan's balance of right and left brain use is remarkable. Any time I need some humbling about my own blend of talent and intellect compared to that of the average Joe, I'll watch one of his tutorials and remind myself how important it is to exercise the two in concert as frequently as possible. Dan is to tutorials what FabFilter are to plugins.

[@sonidojamon]

Can't wrap my head around to how to mix/blend real + sampled kick tracks when EQing 2 tracks independently before summing to a kick bus (and then add more processing) I made sure both tracks were visually time and phase aligned. Then I was forced to downmix the two tracks to save some CPU, and started going crazy. In the resulting waveform, both kicks had moved slightly in time, creating a strange and longer waveform. I had made sure that the recorded kick was time/phase aligned with the overheads (did the same with the rest of the drum tracks. In fact, I've become obsessed with this lately), and now everything was all over the place because of individual eq processing. I am 100% sure it is not a latency compensation issue. When mixing down/freezing tracks, my daw compensates for plugin latency automatically. So I decided to mixdown each track individually to see what was going on. Zero phase eq processing created a 3x longer kick on each track (because of different frequency phase missalignment, I guess), and linear phase created lots of pre-ringing and missing transients. The less destructive setting was linear phase in "minimum" setting, but still had issues. All of this considering I was using a sample kick sound that was nothing like the recorded one, except for adjusting the pitch to match the fundamental note. I got rid of HPFs and LSFs I was using to polish low end, and things started to improve a little. Then applied those filters back in the kick bus afterwards, and things kind of started working again. But now I'm not confident anymore about the kick staying phase aligned with the rest of the drum tracks (specially OHs) unless I bounce the bus output to audio and compare the timing to the overheads. And that's a bummer. If I've understood correctly how this works, despite of visually aligning the recorded audio tracks and its transients, heavy eq processing can missalign back the timing of frequencies separately, and the only way to make sure everything's ok, you have to use your ear, or bounce the individual/bus tracks to audio after processing to re-check the alignment before summing in a drum bus. My final thoughts: the best you record things and the later you process drum tracks after summing, the better. There's only so much correction and tweaking you can do before things start to get all oven the place and out of control. I really struggle to get things right when I receive badly recorded tracks for working on a mix. I feel like I spend 90% fixing the impossible before I can even enjoy the process.

[@edmccormack8032]

Incredibly detailed tutorial! Thank you so much for making this!! Regarding the pre-ring demo @ around 3min, I'm still a bit confused about two aspects of that phenomenon: 1. From what I could gather, my understanding of pre-ring is that it is simply an "incorrect, early start" of the processed audio, relative to the original, unprocessed audio. Further, this "early start" displacement is caused not by the EQ itself, but by the DAW improperly compensating for the plugin's delay. In other words, my understanding is that if I were to just drag the printed audio of the "Linear Phase" waveform (i.e. the image at 3min) to start where its departure from the zero crossing should begin (i.e. departure to begin at the cursor where the above "Minimum Phase" waveform begins), wouldn't Linear Phase then be "flawless"? Though, based on the visual differences in the resulting waveforms @ 3min, I'm assuming the answer is no, and that there is something about this Linear Phase's delay and its compensation that is actually warping the original signal (and not just globally displacing it). It is this "warping of the original signal" that I can't wrap my head around. Can anyone please help me understand what is going on? 2. My second confusion is in regards to these differences in the two resulting waveforms shown @ 3min: Visually, it seems like the high frequencies that form the attack of the kick drum in the "Minimum Phase" waveform are nowhere to be found in the "Linear Phase" waveform. - Does Linear Phase processing somehow result in "lost" original frequencies? I'm really confused. Any clarification would be greatly appreciated!

[@georgesimpson1406]

Very enlightening. It would seem that only pass filters are the things to worry about in mixing. However, one can clearly hear phase adjustments on a master track that isn't in paralllel with anything too. I figure this is a delay that will make certain frequencies feel pushed back, in a similar way to a stereo haas effect but about the relation between separate frequencies rather than speaker channels. My process usually involves simply playing with Ozone's settings however and no particular rule comes into play, i tweak the continuous slider until it sounds less...lumpy and phasey (?) ...or i just leave in min phase "analogue" mode. Very subjective yet definately there. In a way, fully linear sounds flat and no phase correction sounds 3d but often in a wrong 'uneven' way. I kind of doubt this is audible except on very complex signals...such as a master bus. But maybe there are situations that do not involve parallel processing that are about the small timing differences caused by eq where one simply is more preferable.

[@drampadreg1386]

This tutorial has exactly the information I have been looking for, and applies to more than just rock like many of the tutorials and I don't record much rock so it's very useful! Subscribed! Thank you for the no BS ego free tutorial Fab Filter. I have heard a few mastering engineers praise Fab Filter as a very useful software company which brought me here in the first place, apparently they want us to get a good sound proving their products value, makes sense to me. I'll be spending many hours watching and re-watching these videos until I absorb as much as my brain can hold. I'll also be getting some of these Fab Filter eq's and comps etc. and put them to the test, and expecting good results.

[@PaulMichaelCardon]

This video taught me so much more about EQ's and their phase-shifting than any other video. Also helped to clue me in to VST Plugin Analyzer which has taught me a lot about all the plugins I use.

[@DavidPixleythemuzzlZ]

+Paul Cardon what is the name of that free analyzer?

[@DavidPixleythemuzzlZ]

+David Pixley Christian Budde's analyze -- got it!

[@Thomas..Anderson]

This is almost a prime example how such videos shouldn't be done. Why talk over the audio example with which you are trying to show something. Be quiet for just a few seconds please. As such, audio examples are useless with speech over it. Another failure. Kick drum you used. You should use just one kick and not a sequence.

[@sanjacobs6261]

5:20 I can't believe one of my favorite DAWs, Reaper, still calls it "invert phase", when what you're actually doing is inverting the polarity. Even FL Studio got this right!

[@nihilisticalbino]

Inverting the polarity of the phase, maybe? Idunfucking know but maybe they're both right

[@sanjacobs6261]

@@nihilisticalbino It just doesn't make any sense to say to "invert phase", because phase is time, it's like saying "the opposite of 15th of October, 1874" like what even is that

[@Bonn5656]

Ableton Utility?

[@DanWorrall]

Good answer. To add to it. those curves I showed in the analyzer are created when the two correlated signals mix together: displaying them for just one of those signals would be inaccurate and misleading.

[@fidrewe99]

Is there no plugin to monitor the phase as a function of frequency and to correct for phase shifts without changing the amplitudes? I've noticed a very significant difference in the sound of (even isolated) vocals for linear vs. natural phase EQ in the low end (and a difference depending on whether the you use a low cut or a low shelf with identical slopes at the low end). It's partly going to be a matter of the transients due to pre-ringing, but there's also clearly a difference in the tone. Since no phase cancelation is possible in the case of just one track, it seems like the relative phase of the partial waves affects the timbre of the sound. I also checked this using just two sine waves in matlab and varying the phase delay and I indeed can hear a difference in the subtone (the difference frequency of both waves), the composition and intensity of the high buzz that probably consists of sum frequencies and even the perceived value of the interval. Why is nobody talking about this effect?

[@omniburn]

I know this video is kinda old now and has been done with FF Q2, but I've been trying to get the same results with Q3, and it doesn't seem like I have the ''pre-ringing'' problem even though I tried to exaggerate the settings. Has it been fixed on the new version of Fabfilter Q?

[@baddiemcbadbad9231]

Still, when should I use linear and when should I use zero Latency? From what I'm seeing here, linear should be the go to, but why don't people use it as often? Because of the ring?

[@audioglass]

Wow. I'm gonna get my head around this. Phase has been bothering me without me knowing what it is for a long time.

[@spider853]

right, it's simple to think about phase in simple oscilators, but when you have a full mix, what is a phase? How do you get the phase of components in a full mix? doesn't FFT has fixed phases? confusing

[@WillyJunior]

Wow Dan actually speaks normally here. When did he start doing the super uptight, tense speaking thing?

[@Ein-Stuck]

Many of these problems are predictable. Why can't corrective measures be implemented? Is there not enough ones and zeros to combat this?

[@TheLiverX]

I had suspicions, that EQs do something to the phase (FL Studio's built-in EQ 2) either adding a delay to process a signal window or butchering the phase of the signal. Really, built-in EQ did both delay and phase change, so I had to add equal amount of EQ for each guitar IR track, I had to equalize the number of EQs to save phase relation. Yet, just to make sound better I added artificial delay to IRs (3-10 samples at 44.1) to get the low back in line, but still, that was a revelation at least.

[@Dan-pq1tp]

TL;DR: Use Linear Phase mode for Parallel Processing (aka: when there are two similar/identical signals).

[@Dan-pq1tp]

Relevant sections: 5:46 - 6:37 = Definition of "correlated signals" 18:01 - 18:22 = Summary of when to use Linear-Phase mode; basically almost never. 11:39 - 13:33 = Demonstration of Linear Phase VS Minimum Latency differences for correlated signals

[@stephen1561]

I appreciate you ♥

[@RichardMedhurst]

cheers fam

[@ashwinireact]

i love you

[@MiKEY_SANZ]

you're a fucking hero

[@michaelcarrillo4377]

Ok, am I right when I say minimum phase modes are generally going to give you some extra cut above the cutoff when combining correlated signals and linear phase is not?

[@pgmjsd]

Hm, yeah... as if you've mixed in the original non-eqd signal... you'd have some phase effects. Great vid.

[@adrianzag]

Dan Worrall. De-mystifies a complex subject so perfectly. Absolute legend.

[@shadrachsolomon]

This answered the most difficult question whether to use Linear phase eq on the master bus or not. Thanks for the video.

[@mallek1989]

When he said fabfilter at the beginning, I thought he said "fuck filters" and almost spilled my drink on the laptop hahahahahaha

[@FunkZzzz]

lol

[@xaosnox]

I kinda wish I'd never seen this! Now my head is spinning! Excellent info, as always, but I'm either braindead from lack of sleep, or this has just opened up a can of worms that it will take me months to put in order.

[@davidhayman9330]

thanks Dan, so well explained and very helpful!

[@skawa80]

wow, I just gather my jaw from the floor now. You make my day.

[@tohtorizorro]

This stuff is explained and visualized exceptionally well, such a shame I didn't find the channel earlier. Still, I have to ask does some one really hear the differences in the snare sound? Even when he flips the phase 180 degrees?

[@DanWorrall]

Fair enough, yes the phase response could be displayed. It would be a fairly boring straight line in all the linear phase modes of course!

[@Tapepusher]

So, should I eq my kick drum with a steep filter or is that messing up its phase? Perhaps a less steep 12db hp filter is better?

[@yony_music]

This is better than any netflix show😎

[@vitaliistep]

By much :)

[@finnnnnnnn1258]

I always wondered why trying a parallel “air band” made everything sound so thin in the end, it wasn’t because I was adding too much high end, it was because of the phase cancellation caused by the minimum phase EQ! Invaluable info here, wow.

[@Mdjagg]

I bought the pro q 2 a few days ago, before I really understood all of the possibilities and features. I'm so glad you all have taken the time to make these amazing videos, as should any producer of any plugin, or really any product. These videos are also the reason I will be buying the pro bundled soon. Well thought out video and video series, I had a favorite eq for years and now I have a new one.

[@obecojb]

Great! Know I understand what happens when I sometimes not trusted my ears. Thank you

[@michaelrobson1627]

Thanks so much for making this video!!! I learnt so much and explains so much of what used to confuse me about eq in my mixes. You are the man!

[@WAMProducties]

this is mindblowing, so glad I finally looked up what linear phase eq means

[@FunkZzzz]

+1

[@BeyondtheEndMetal]

Dan is one of the smartest dudes ever, I've never seen anyone make tutorials like him... I wish I could instantly have the knowledge he has and be able to make insanely fast mix decision based purely on knowledge.... maybe one day.

[@allourep]

Somebody needs to make that Christian Budde VST Analyzer plugin available for Mac

[@victorgoemans8644]

I wish I'd found these videos earlier. They are absolute gold. The other day I noted something remarkable while working with parallel processing on a bass - a duplicate of the signal was routed to an aux channel with a compressor and saturator (Saturn's heavy saturation mode). The dry and wet signal were mixed together with a compressor and yet another instance of Saturn (warm tape). With the warm tape saturation plugin on the bus, I noticed that - even though it was already in 8x oversampling mode - there was a huge difference in sound when turning on the Linear phase mode. The bass became a lot more punchy, as if I'd turned down the attack knob on the synth completely. I can't really wrap my head around why this would be. Is that because there is some pre-ringing going on, causing the attach portion of the sound to (partially) shift?

[@jameslangford3613]

Really nice to be presented with some actual solid metrics on how each mode impacts phase under different circumstances. Thanks for the effort, what a great video!

[@John83118]

I'm addicted to this content. I read a book with similar content, and I'm addicted to it. "The Art of Meaningful Relationships in the 21st Century" by Leo Flint

[@leovodica9975]

2024: I consider my mind to be officially blown. I found this YT on reddit from 2020

[@Ekagraum]

This is the most useful video about EQ i've ever seen, really, thank you a lot!!! Recently i've started to play with morphing sounds into one another (like a vocal to a kickdrum and bass) and i faced a lot of issues presented here while EQ-ing but had no idea why they happened... you just saved like 10 ideas i started and was so frustrated about them i wanted to throw them out, but now i think i know the solutions.

[@jcalla28]

Fantastic explanation! Highly educational stuff!

[@UGHeights]

I've put it on replay for at least 4days now

[@TerrenceWFunk-ex6qd]

Incredibly well done video. I actually started watching this as an embedded video on another page, but had to follow the link to see who the author was. Finding informative, straightforward, measurable results on the application of science toward a subjective endgame is literally the definition of Audio Engineering. Videos like this are immeasurably valuable in that pursuit. Thank you, bigtime.

[@joaoldmedeiros]

why are you checking the comments for people from the creativelive stream? go watch the video and learn lol

[@CraigFlowersMusic]

Your subwoofer is fooling you. There's way too much 50Hz. I have a small deficit in the low fifties too, so I can't imagine how overwhelming it actually sounds.

[@leonid998]

This video doesn't explain why pre-ringing sounds like reverse echo and how exactly it is produced by the linear phase eq algo. There's the article on cravedsp site explaining. And if IUIC it involves no DAW-related latency compensation. Samplerateconverter site has a more detailed one.

[@4th4444]

so essentially you don't know what your trying to achieve and your just trying everything just for fun? not very helpful but thanks for the various pointless A/B's.

[@timothygilman4848]

Thanks for taking the time to put this together. This is great content. I've been working on a mix for a friends and I had everything sounding pretty good, but made a few tweaks of the EQ and walked away from the mix. When I came back the mix had lost low end and nothing I did would fix it. I thought maybe a phase issue. Based on your video I'm going to go back and reassess all of my EQ moves. Again great content... Do you do a news letter too? I just subscribed to your channel.

[@dankwarmouse6248]

Are there any papers of the mathematics behind this effect I could read?

[@TheSlowGrowth]

not really papers, because it's not recent research but "basic" mathematics. You can look up the laplace transform, which can be used to express the amplitude and phase response (which together are the frequency repsonse) of a filter with complex numbers. You can find the frequency responses of typical filters as formulas on the web. You can then "add" together the responses from two filters much like you would add together the signals in your daw. The resulting frequency response is also what you would observe in the audio. So if your mix consists of an EQ A and an EQ B both beeing fed by the same audio, and you mix both together with the same amplitude (e.. 0dB) then the frequency response of the resulting signal would be the sum of the laplace transformed frequency responses of the individual filters.

[@chrisbauer1925]

You may also gain some insight by thinking about the relationship between voltage and current in resistor/capacitor networks, as this is how minimum phase filters are created in the analog realm. EDIT: www.analog.com/en/analog-dialogue/articles/phase-relations-in-active-filters.html

[@kazkaten]

Why my VST Plugin Analyzer shows different curves on the same ProQ plug-in at the same frequencies ? Becouse i measure only one channel? How to measure 2 signals? And is it possible to use this VST Plugin Analyzer in real time inside sequencer (DAW) somehow? How it actualy works? Anyone?

[@mrshiney2]

So.... Use your ears, can be helpful??? who would have thought. But now I know what is making it sound funky and I can sus it out. but still use your ears

[@aleksandardzhelev1810]

This is definitely the best tutorial i have ever watched ! Thank you Thank you Thank you Fab Filter and Mr Dan Worral !!!

[@CLaw-tb5gg]

So.. is the version of this for stupid people like me basically: use linear phase unless it's a source with strong transients (unless you're dealng with two very similar tracks e.g. two mics on the same source)?

[@RudefoodArchive]

Can anyone please help me!? When Dan shows the analyser explaining how much phase is created for each frequency is that showing the effect on the two snare mics played together or just one of the snares? Am a bit confused. Is he saying that for one fo the snare sounds the particular frequency on the graph is moved out of phase, therefore it would cause problems when played with another mic of the same instrument? Any help much appreciated, thanks!

[@robertoquimi1349]

You are the most fucking cool guy in the world. Thanks for helping with the tutorial and for the use of amazing and useful plugins

[@ribvicky]

Thank you so very much for these amazing tutorials! I have learned so much from your videos. Much Respect for your knowledge! You are just amazing!

[@Bigyhx]

Why doesn't the Pro-Q itself tell which frequencies are being affected by the phase shifting so we can decide which processing mode to use?

[@AudioBabble_]

Great tutorial, and a nice tune too -- presuming it's Dan's own? Anyone know where to find it?

[@AledesChica]

wowww.... 2021, usefull video!!! thanks

[@branchyapple]

still dont udnerstand why that left graph is always ending on 0DB... 8:22

[@lolilollolilol7773]

Looks like the phase shift is equal to - derivative of the filter with respect to frequency for minimum phase filters.

[@s1mpl3me]

my head hurts

[@Schaddn]

I just don't understand why the phase shift appears in the signal when you eq something

[@MassaiWorrior]

i will pay for a french traduction !!!!!!

[@Timmsstuff]

Yes, but in minimum phase mode it could be handy, especially if you could hover over that line somehow and have a popup that shows the amount of phase shift in degrees

[@amandembla7109]

In the mix?

[@riskzerobeatz]

Reaper + Fabfilter = Epic win!

[@Bring_MeSunshine]

Blimey Dan, I certainly shut up and listened to that, so much technical depth. Certainly put me in my place on the Linear Phase EQ learning curve - basecamp. Easy to listen to and well explained. Worth a revisit, me thinks

[@petter9078]

Looks like the phase is the derivative of the EQ curve.

[@Chuggalugg]

You guys make some amazing tutorials with your plug ins. Thank you - from the bottom of my heart!

[@LAF_23]

Anyone know where i can find the song playing at 2:00 ? That bassline is just so sweet

[@xaosnox]

I kinda wish I'd never seen this! Now my head is spinning! Excellent info, as always, but I'm either braindead from lack of sleep, or this has just opened up a can of worms that it will take me months to put in order.

[@kelsounds3131]

Same😅

[@iamsunrai]

totally awesome vibetown

[@quevagregory15]

👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍 👍

[@ColocasiaCorm]

I was going to say.. preringing is never this audible.

[@MaxLohMusic]

9:00 holy shit, it's the NEGATIVE of the DERIVATIVE. Math classes coming back to haunt us in music production.

[@victorgoemans8644]

@16:19 - what kind of shape? A Gerson shape?

[@IguanaFilmArts]

Very good and informational video. But why are certain DAC's forcing us users to either choose a minimum phase or linear phase filter? Why no filter at all and play the song as intended or am I not getting something?

[@LeePuu]

i don't get it, which eq should i use to cut out bass frequencies with?

[@RadicDotkey]

I'm confused. What is minimum phase mode?