Sympathy For The Devil (Linear Phase for Crossovers and Oversampling) 

Dan is the only person than make me put on headphones even though I don't feel like it.

The thing about pre-ringing is that it's... counter-intuitive. We see it on a signal plot, but it's not an artifact. It's just what filtering *means* . If you think about that impulse, it has energy at all frequencies. So it makes sense that if you low-pass it, you get a smeared out impulse containing only the low frequencies. With a minimum phase filter, the smearing happens after the impulse; with a linear phase filter, the smearing happens symmetrically around the impulse. And then of course, if you high-pass it, you're going to get the exact opposite... so the impulse, swept down since you've removed the low frequencies. And that's what you get. And since this is all beautiful math, it indeed all re-combines perfectly - because it was never really an artifact, it's just a fundamental thing about what filtering does to signals. But what about the actual ringing down below zero, I hear you say? Well, Dan used the wrong kind of wave editor here :-). He should've used one that does proper sinc interpolation between samples, which is the *actual* analog signal you get when you play back those digital signals. And if he'd done that, you'd have seen that... the ringing around zero was already there to begin with, in the original Dirac impulse! It's just that the sample points line up with the zero crossings so you don't see it, and the filtering makes it evident by mis-aligning that. So why can we hear pre-ringing when you use settings which are extreme enough on something like a kick drum, if it's not really an artifact? Because our ears don't work in the frequency domain - they work in both the frequency domain and the time domain. The switch between those two "modes" happens at around 20Hz or so (but it's not a hard boundary). Stuff below that we hear as events in time; stuff above that we hear as tones and frequencies. So when our ears process a filtered signal where the filter is at a very low frequency, they hear the signal as events in time, not as a frequency. And indeed, the pre-ringing caused by *frequency* processing with a linear phase EQ ends up moving some signal *backwards in time* , so when our ears hear it *in time* since it's such a low frequency, that sounds off. Conclusion: EQs are broken at low frequencies, because our ears *don't work* in the frequency domain at low frequencies, so an EQ is doing the wrong thing. But if you must use one and majorly screw around with things that far down, then yeah, minimum phase ends up sounding better, because it doesn't violate causality and so is less offensive in the time domain.

Best audio engineering content on youtube! Fight me! I'm so sick and tired of this "top5 eq/compressors/limiters/saturators" crap, it's video equivalent of shitposting. This is real content! Great work Dan!

Phase is one of the ways your brain can locate the direction of sounds, so it is not surprising that we can perceive phase differences between ears but not on their own.

My dissertation at uni was based on an experiment where I shift phase of white noise around a frequency on one side of the headphones. This creates an artefakt of our auditory system where we hear a tone in a location. I got people to record where they heard the tone spacially. People couldn't believe that when they swapped headphones round the tone stayed in the same location. Binaural phenomena are interesting for constructing a model of how our auditory system works.

Love your channel - incredible video!

Dan, you're Mr. Einstein in audio! Bringing all the small complex details together no other can do. This is brilliant.

Every DW video is a priceless master class. He is the only "youtuber" that makes me need to pause the video and take notes.

Dan Worrall: the David Attenborough of daws. Thank you for showing me the majesty of phase in its natural habitat.

To my surprise I can hear a difference when you toggle bypass on and off at 4:57 listening on Airpod Pros. Sound a bit more nasal when it’s turned on. But I’m not 100% sure because it might simply be differences in how you speak. It could also be that the RU-vid codec exaggerates the effect compared to the WAV that you were hearing when you made the video.

Regarding the symmetry of the ringing in the oversampling filters of Saturn 2, it is correct that for the equivalent minimum and linear phase filters, there is a difference in whether the ringing occurs after the impulse, or symmetrically before and after respectively. However, this only really applies to FIR filters, which can be minimum or linear phase, or anything in between. As the name suggests, the ringing in IIR filters is potentially unbounded, so it's not really meaningful to compare the impulse response of an IIR and a FIR filter in this way, because it's not really practical to have an infinite pre-ring in the first place. If you design a windowed FIR filter however, you will see this exact difference between a minimum phase and a linear phase variant of it. The reason why the responses in the case of Saturn 2 are different relates to this, and is perhaps deceivingly simple: the minimum phase oversampling filter is altogether different from the linear phase filter; the former being some sort of an IIR filter, and the latter of course a FIR filter. Not only that though, but if you look at the magnitude response the minimum phase oversampling filter is quite a bit steeper than the the linear phase filter, and consequently has more ringing as well. Additionally, the "interesting pattern of differences" you see from the The Drop's linear phase oversampling is most likely caused by the window function of the FIR filter kernel. Because the impulse response has to be finite, the window function crops it to a certain width, making it imperfect and leaving behind ripples like this in the passband. For a well designed FIR filter such as this one though this is not an issue, as the ripple is well below any sort of audible threshold. Hope I got everything right there, please correct any of my mistakes in the replies :)

Dan, thank you for this insightful video and your empirical approach. I'm not an audio professional (I just listen to music a lot), but I'm fascinated by the technology and have been using EQ extensively for a while now. This video answered many questions I've been thinking about for months, and it has given me even more things to think about in the future. This goes for many past videos too. You really motivate me to delve into the tougher, less surface level parts of music production and processing. Keep it up!

Is unbelievable how clear and precise your explanations are. Thank you for your amazing job done to prepare this kind of video. Cheers from Italy!

"-100 dB is negligible." n OTTs with 20:1 thresholds: Allow us to introduce ourselves.

Hey Dan, Thanks so much for making this video! It's something I've been struggling to understand and research for over a year. It took me a while to figure out that Fabfilter's Q setting was different to that of my other EQ's (And that the frequency at the cutoff frequency was only being attenuated by 3db). This really helped clear up a few of the questions that I had left about crossovers.

Thanks to Dan's videos, I came to love messing with phase. It's just another tone control for me. I routinely tune crossovers to a freq/note that's not in key, or dial out a resonance. Sometimes it works, sometimes it doesn't, but it's a good bit of fun to listen to the slight freq shifts and how they affect the sound. You can also roll your own stereo spreader if you know what you're doing.

Excellent material, as always I learned a lot. One nitpick though - that I believe is important. With two bands, you don’t need two filters, but one - one signal is “x”, rest is “input - x”. What this means for the pre ringing null test - it doesn’t mean it is not there, just that they cancel (opposite). I know you make this point later in the video, but this mathematical perspective in my opinion makes it easier to understand when it is going to be transparent. When dynamics reduce a band by 6dB, only half of the ringing will be cancelled by other band flipped phase.

6:07 - I was listening on monitors, but kept on smacking the "mono" button to see what it sounded like 😊Thank you for another great video!

I can definitely hear the difference. I thought I was just imagining it but on the pink noise part it was very very obvious. It's difficult to put into words what the difference is, but it's kind of like the same feeling as looking at yourself in the mirror versus looking at picture of yourself. It's just off in ways that are difficult to describe but are very clear to you.

As soon as I start to feel like I'm a pro, Dan Worrall drops a video that humbles me into thinking different.

Jo, another thing to elaborate on is why you can hear a difference in sound when just changing the phase in 1 channel is due to Haas. The Haas effect is often seen by producers as an effect of creating an interesting stereo field by delaying one of 2 channels, hence creating a difference, but that is not actually what the Haas effect means. The Haas effect describes that you will perceive a sound to come from the direction you hear it from FIRST, even if you hear it from somewhere else way louder. Meaning that even a slight change in phase in 1 channel will change where you feel the sound is coming from and its directionality, with all else being equal. For how this makes sense, imagine you're in a cave. You might hear a sound coming from somewhere amplified through a cave system very loudly, or a landscape where you hear a sound loudly reflected from a cliff. However regardless of how quiet it is, if you hear it from someplace else first you know that is the shortest path between you and the thing you're trying to locate. Phase difference, or more accurately, the time difference between 2 channels is very significant to how we perceive directionality in sound. This is actively used by the "agent" system in our brain to determine what a sound means to us and where it is coming from. 2 other interesting things related to this, when figuring out where a sound is coming from, people will usually turn their head, as the change in phase observed during this rotation or comparing of the initial with the latter allows the brain to pinpoint a direction something is coming from to an insane accuracy. The thing that it checks for is phase differences between both ears, not loudness. The other thing to consider is that this phase change perception is also related to the wavelength of the frequency, as turning your head will have a different effect on the phase of each individual frequency. This also explains why we hear differences in stereo channels with different intensities across the frequency spectrum. Little to none in the bass (as the wavelengths are so large that the phase change is very minimal between both ears), most in low mids with a gradual falloff to the top.

... to me, i can hear the difference. My translation is: it's like an Imager. When u activate/deactivate MB, the image from mono turns 45 degrees left/right, lower and higher (360degrees) with a slight fattening on the low frequencies. Of course i can give an example, but it's an image in my mind. Love ur surgical work! Best regards!

Oh wow, I can hear the difference night and day, I wouldn’t even say it’s that subtle but it is hard to describe: with the crossover turned off there is a perceived fuller lowend on your voice, the stereo image feels a bit wider and strangely I notice the sibilance more (perhaps due to transients). With the crossover switched in everything feels tighter, narrower in image, the low end doesn’t have the same fullness (but it’s still present 🤷‍♂️). There’s a sense of softness to high frequency transients with the crossover engaged. I did not expect to hear it clearly so started closing my eyes to test and pausing as soon as I knew. Was right every time. Using Apple earbuds! Weird, and great video :)

I already watched this video, I came back for the new thumbnail, still worth it.

I hear it. With the crossover switched in it's definitely thinner and more honky around what I'm guesstimating is 500hz. The bypassed version is fuller and more natural to my ears. Not sure I'd notice if it were left bypassed or engaged statically, but very noticeable in a A/B comparison.

My experience with phase shift when done in a binaural setting (like in this video) is always that the audio seems to "lean" towards the unshifted channel. This is especially prominent in the pink noise test, where the unshifted channel feels as if it has a boost in volume at the phase shift frequency. I made sure I was listening to a perfectly binaural signal (IEMs included) and this is still the case - almost as if my brain is doing the summing and notching within my head.

stunning episode, very cool

As always really good info from Dan.

The manifestation of pre-ringing in linear phase filters is a vivid demonstration of a rarely acknowledged property of high-order filters: they are mathematically equivalent to over-damped oscillators. Ringing occurs at the crossover frequency of the filter whenever its high-Q internal feedback circuits are triggered by an external input. The amount of over-damping determines how quickly the ring decays before and after each impulse. If you increase the Q to the point of critical damping, the ring will persist indefinitely, and if you pass that point into under-damping, the filter will spontaneously oscillate. The upshot of this analysis is that the ring is not an amplification of the input pulse - it is a transient signal generated by the filter itself. @16:05 The reason the minimum phase oversampler produces more ringing than the linear phase oversampler is because the steep low-latency filter in the MP oversampler is less over-damped than the higher-latency filter in the LP oversampler.

Great. Learned a lot

I can't say I can hear a single rotation of phase, but I do recall once I started adding more, I'd hear almost a wetness (like almost watery or liquid) or thickness in the sound, which would eventually turn into what sounded like a lazerbeam effect with the highiest pole filters.

Hi Dan, Cool Video! This time I would like to give you full 5 of 5 Stars. Thanks a lot for pointing some issues out concerning my questions. Blessings, Tim! :-)

We can all definitely hear relative phase differences but only between the ears. This is an important part for locating sounds in the horizontal plane. IIRC we are most sensitive to that in the 200-800 Hz range. Above it's loudness differences, below the sense of location gets lost the lower a sound gets. The wavelengths become so large that phase difference between our ears is too small.

I would describle the crossover phase shift as a "laser-like" sound. Whenever there is a vertical line on the waveform (e.g. transients, pure saw/square), it will become "dispersed". Lower frequency arrives late. Like a superfast sine sweep from high to low frequency. I learnt to tell the difference by extensive use of the disperser effect. Which is basically crossover filter stacked multiple times. The crossover phase shift sound is a very, very subtle version of the disperser. The sound will also be much more apparent when followed by distortion. Especially on pure saw wave. When distorting/waveshaping a pure saw wave, it will basically become a square, losing even harmonics. If there is a crossover filter before the distortion, the reaction on the harmonics is much more different. The even harmonics will be preserved, the frequency response will also be changed.

Now with a proper thumnail I will finally watch the video!👌

Love the new content, Dan, great to see your videos regularly appearing in my subscription feed again! Any chance of some more of your Channel Members mix feedback content some time soon too?

Once again a clear and informative tutorial, thanks for all these videos Dan. As for the minimum phase toggling test @4:54, much to my surprise, I can hear a difference. To me with x-over switched in (bypass light off), your voice has ever so slightly more edge, a focused presence if you will. X-over off your voice loses some of that focus and gets wider, more relaxed in tonal balance. To me this gives an image of it extending more evenly to lower frequencies. Listened on laptop with cheapo earbuds, will be interesting to try this later in my regular studio setup. Now isn't that great, finding just another thing to worry about. 😜

In response to your call to action I can totally hear a difference with the filter engaged. When engaged theres a difference in how certain frequency ranges present themselves in relationship to one other on the time domain albeit quite subtle. One way I sometimes think about it is imagining the signal as a 2d vertical line as if it were coming from a single mono speaker where top to bottom represent 20k to 20 hz. As phase shifts are added the signal feels less like 1 full sound arriving at once, and more like individual pieces arriving slightly offset from one another. Almost like a train coming towards you vs a bunch of cars on a highway. Ive heard some describe it as "whooshing" but thats more in relation to describing HPF phase shifts around their cutoff point. In reality, ive probably done a horrid job explaining this and just seem batshit crazy at this point. I just know most days being able to hear slight offsets like this is a curse above all as it drives my OCD up the wall and will derail a mixing session if im the only one in the room.

Thanks a lot Dan. Best !

You need a “Anyway let’s do a null test” t-shirt

So did changing the thumbnail on your video work? I watched again but wondering if there was an uptick in the views :)

Hey Dan! First of all: Thank you for all your amazing videos. Big fan here! Any possibilities that you upload a video to "softclipping" on the master bus? Recently I more and more heared about "softclipping instead of limiting". Thank you so much and keep up the great work! :)

Hi Dan! Would you consider doing a tutorial on Goniometers? I understand basically what they do and what they show (thanks to your earlier videos among other resources) but there's still so much about them that I don't get. Why is it that white noise creates a mist across the entire field? Why do stereo Bass synths create these weird and cool geometrical patterns? Is there something to be learned from the shape of sounds in the goniometer when the shape is geometrical versus not, or should they just be enjoyed as cool visuals, and the real info is how much correlation there is and what will be lost in mono, etc. If that made sense :)

I love your videos! Any chance to see your templates/customizations/workflow on Reaper explored in future video?

I haven't even watched this video at the time of writing this comment and I already know I'm going to enjoy it

Think yourself into a sferic image. 360 degrees each way, by the size of your volume. Volume is actually the size of those. That's how I picture sound. iZotope Insight has those ways of showing actual sound (analyzer). Some people imagine sound as fab's analyzer. From 0 to infinite (nyquist???). Keep up the good work guys!

Yeah this thumbnail is now absolutely genius

Lmao I’m here for the thumbnail change

To me, that phase shift sounded like a bump in perception of mids. Maybe kind of like a wide bell +2dB at say 2kish. Maybe a bell around 300 -2dB. Maybe its placebo. But, I'm eating dinner at my desk in my studio and I shot my head up from my plate twice when I thought I heard the same change in your voice. Both times you'd brought PRO-MB back into the mix. So, there you go.

Awesome video as always, the tune used for the binaural test was fucking awesome. Difference was clear as day, sounded like lopsided phasing issues to me lol. You really need to do a full length glitch hop/bass music album. Do you by any chance know of the artist Tipper? Very reminiscent of his early work. I always hear tippery influences in your music and was wondering if thats just me imprinting my taste onto your music. If you are familiar with Tipper I am curious about what you think of how he masters his music. His more aggressive stuff sits around -5 lufs and dynamic stuff around -13 lufs.

That static phase shift introduced in Pro-MB minimum phase mode is definitely audible on certain sources - I've actually intentionally used it on kick drums, it gives a weird kind of electro-thump depending on where you set the crossover

Something else for people to keep in mind with regards to linear phase and pre-ringing audibility is that there's a 99% change, maybe more, than whatever DAC you are listening to tings on is an oversampling DAC, and the filter it is set to use is linear phase. While it isn't universally true, many DAC chips allow the designer to select from a couple of linear phase and minimum phase filters, most devices choose to use a liner phase filter with a sharp rolloff. You are usually going to have linear phase filtering happening for your digital lowpass filter, like it or not, just because of how DACs tend to be implemented these days.

Anyone know what program he’s using to show the null tests? Not plug-in doctor, the one that makes its first appearance at 9:01, where to different tracks are shown in the folder that contains them shows an overlay of the boat

of course we can hear the difference in left and right; it's kind of like applying the haas effect only on a small part of the frequency spectrum. if you don't have the two signals (left and right) to go into your head simultaneously, why would it otherwise be audible if you delay some frequencies by a tiny bit?

You can still achieve a linear phase crossover with an IIR by using the difference of the lowpass (or highpass, works both ways). Its only when you use two filters that there is phase shift… then theres linkwitz riley filters which are essentially two filters stacked up, like what dan did in the last video, but that phase shift turns into a 360 degree phase shift and as such can be described as linear phase, although linkwitz-riley filters fall apart when you have too many of them close together and the phase shifts interact. Filters really are quite wonderful, all this stuff is just delays, add/subs and multiplies and arranged in different ways give us so many interesting results! What filters/processes haven’t been discovered yet?

Second comment - on why linear phase results in less ringing than minimum phase. Dirac delta is all frequencies that happen from infinity to infinity. Luckily, they cancel each other out except for one sample. Linear phase ringing is symmetric, but smaller as it results only from those very high frequencies that were present in the original delta, but we removed them with a down sampling, antialiasing filter. With a minimum phase filter instead, we shift all frequencies in relation to each other - including ones below new Nyquist - and they no longer cancel out at sample positions so nicely.

Hey Dan, I thought of something for minimum phase crossovers a while after watching this video. What if, after configuring the crossover filters correctly and using minimum phase filters instead of linear phase filters, you add an all-pass filter to the low band and the high band after the crossover filtering to fix the phase response caused by using minimum phase filters? (To my eyes, the phase response of combining bands after splitting them with minimum phase filtering looks nearly identical to the phase response of an all-pass filter, ignoring differences in bandwidth/oct and center frequency, since those parameters can be changed when using an all-pass filter) Would this be a feasible way to achieve minimum phase crossovers with a flat frequency response and a flat phase response (instead of using linear phase crossovers to fix the phase response), or would chaining an all-pass filter after the band splitting cause its own problems? Edit: It occurred to me that there isn't really an "inverse all-pass filter" which can undo the phase response of a normal all-pass filter (unlike how other eq filters CAN completely cancel out in terms of frequency response and phase response), so my idea probably won't work in that case...

How do you deal with the latency introduced by LP? Do you measure the time-difference somehow and then compensate? Or are there quicker ways to deal with this problem?

With the minimum phase lowshelf filter engaged, it sounds like the bass frequences are coming from behind me slightly left when the eq is on the right channel, and behind me slightly right when the eq is on the left channel. That's the only difference I hear.

I'm back for a 2nd view as I'm so engaged with the new thumbnail 😄

Great vid as always. BTW I have a question triggered by topic of antialiasing filters. Why are there different outcomes when resampling? Shouldn't it be mathematically identical with just changed/moved sample points if there is only ONE shape recreated sinusoid can take? This is one of the last things within sampling theory for beginners I cannot grasp ;)

The new thumbnail works!

Hi Dan! Could you please explain it to me why it doesn’t null, if i try to do the same crossover trick with linear phase ff pro q 3?

What about only one band on pro MB (I keep using one to sidechain kick to bass, just the lower regions below 150hz just so that the rest of the bass isn't affected) - so without any crossover filters if it's just one band, which one would by idea be the most "transparent", dynamic phase, minimum or linear? It does get drastic sometimes, to even -10db with extremely fast settings - seems to sound nice, and not too sure if I'm hearing much of a difference between different phase settings there - but would love to hear what would theoretically be the most ideal in such scenario.

I have been able to hear phase shift in mono, but only in extreme circumstances. If you run a pure saw wave through a bunch (more than 7) of allpass filters in random positions, it sounds softer, almost like a chorus effect, but without the modulation. An alternative is to randomize the phases of the saw wave harmonics if you have a synthesizer that can do that (sytrus from FL, and xfer's serum I believe), and the effect is even more pronounced.

The puppet satan thumbnail made me watch..great video..Hail puppets

This video is so good, I'll just point out that I didn't understand some things like audible phase, is it a phaser effect? Or is it another definition, I would really like to know There is a question that I have been asking for a while, why mastering engineers sometimes recommended to use a linear phase EQ if it is an audio segment that will be one piece and not collide and fight with another audio segment and this will also answer the first question Anyway, thank you very much for this amazing channel, every time I learn something new 🙌

Hey Dan -- you might enjoy my Psychoacoustics series; part 4 especially covers some interesting effects having to do with strange ways phase can be perceived by humans. Thanks for your video!

I did actually hear a pretty clear difference listening on headphones. I assumed it was a placebo effect, but listening over it again I'm confident that there's some difference there. Your voice sounded fuller with the plugin bypassed, and when the plugin was active, it felt like there was a subtle kind of buzz going on.

I don't know i kinda can hear the phase difference when toggling on and off in my headphones on the first example. Sounds fuller in low mid frequencies to the Bottom with it toggled off... I might just be imagining things

Being able to hear phase difference is if I recall correctly a real thing. I believe I once heard that's one of the ways we are able to determine which direction audio comes from (both the phase difference from one wave first hitting one ear and then the other, and due to various reflections in different parts of a room).

I'm using headphones anc each time you were activating a compressor on one side, I was hearing the opposite side as louder and "behind my head".

can you do a video about the different linear phase settings

You can learn how memorize pitches aka perfect pitch......there are only 12 tones. We use 26 letters everyday 🤯 Great Video

Yep can definitely tell the change between bypass and not bypass even on iPhone speakers (iPhone 13pro stereo speakers)- not sure I could tell the difference long term, maybe it’s the point the change occurs that I can hear - would need a longer sequence for a/b. Very interesting!!

I can hear fixed phase shift but only when fairly extreme, when people have used sharp low cut filters on bass sounds that have repeating sharp transients (sawtooth, square, etc.) It dhanges the character of the sound due to post-ringing artifacts and introduces a resonant character at the crossover point. Try the plugin "Disperser" by Khz. I believe it uses a time delay rather than phase shift, so not quite the same (no post-ringing, I presume), but it sounds like a more extreme version of a sharp low cut on a sharp waveform. A sharp transient (like a Dirac spike) becomes a downwards sweep in a similar way to phase shift on a low-cut filter.

The difference is audible. Vocal tends to get "nasal" quality and that mybe affects, that I also percive less "bottom" on it.

Dan what's your opinion of the new competitor in the "very digital" EQ category, the Kirchhoff EQ which is gaining some grounds recently?

Came for the thumbnail ;-)

It's massive (If you can hear it) 🔥

If you (through the crossover) introduce a 180 degree phase shift for a certain frequency on one of the two binaural channels, that basically means, you swap the mid- and the side-signal for that frequency. Of corse that is extremely audible. Is it fair to say, that you’re hearing the phase shift thought?? I mean, basically you’re hearing differences in the panning of all your instruments in that frequency. But that’s a result of the phase shift and not the phase shift itself… right?

I think i can hear the first static phase shift on headphones, but it's veery subtle. To me it sounds like a slight loss of presence in the low mids, without affecting the highs or the lows at all. I had to pause the video and come back to it a couple times to be sure I experienced a difference, but it could still be placebo. I also have very slight damage to my hearing (Missing a few dBs of mids on my right ear), so I experience all kinds of strange things I can't really explain or put my finger on that other engineers can't hear at all.

Oddly enough Dan, I heard an example yesterday where I *could* hear the difference of absolute phase, having said many times that I wasn't sure if I can ! And, I *think* I can hear it on your voice in this example, too. If I'm not fooling myself, it sounds less warm and full, especially near 100 Hz. I'm hearing less "boom" in your voice, just as I heard less yesterday in the bass synth and kick drum of the example I was listening too, although in that case I was flipping the phase of the entire mix. I scored 4/5 blind yesterday before I got bored, feel free to send me the files if you'd like and I'll try the same test with this example too 😛 (BTW I can very clearly hear the single-channel test in stereo, on both speakers and headphones, even just on your voice. I hear it as a shift in the image, either left or right depending which channel is active)

Damn.... I can hear every change perfectly although i have lost a ltl bit of gain in my left hear....... Being a music producer from seven years really helped train my ear naturally......... I was always insecure regarding my hearing abilities but now i am proud....... Thanks Dan.... Literally

I seem to not understand a fundamental thing about the relationship of frequency and phase - I don't seem to understand what a filter does at it's core. Can someone hint me there? At what key words my research will make me understand? :D (please, I beg you)

4:54 So I definitely had the thought, "can't wait to see everyone in the comments pretending to hear a difference" I heard no difference on near field monitors. Then I put headphones on and was pretty shocked. I heard/felt a difference, but am not sure I have the vocabulary for exactly what it is. It is as if the sound was moving behind me, and without a change in frequency response. Not entirely convincingly behind me, but something like it. Honestly wondering if anything related to this is implemented in things like KLANG.

I did not expect to hear it but I can. To me it makes the sound move behind me, I don’t know how to explain it better.

When the Minimum Phase eq is engaged your voice becomes lighter and has a hint of distortion. It's a bit like running a signal really quietly through a distortion pedal; even when no distortion is happening, you still get an effect. But, in this case, only a tiny amount. Cheers!

I can hear a difference, sounds like low mids are saturated (?) or so, I know the description doesn't make any sense but that's what I perceive 😅 Oh and the stereo image changes

I love how Dan doesn't upload from some time and then he upload like three or four videos that are related to each other

Yo on the iPhone, that experiment you did at 5:00 does make a difference. Less low-end when toggled on.

Noone can ever hear absolute phases in the sound itself, which is why you won't distinguish a sine wave from a cosine wave just by listening to it. What we care about is the phase relationships, which is similar, as you've correctly pointed out, to how a lot of people perceive music (i.e. having relative pitch without having perfect pitch). With perfect pitch, one may find ways to gradually learn it up to the degree when you can finally sing a particular pitch, without hearing any reference pitch beforehand, and you won't be off by more than 10 cents or so. With phases, it's an entirely and completely and totally and comprehensively different story. The phase needs to keep changing in order any sound existed at all. Try running 10 different sounds through a Hilbert transform. If you only listen to the result, without hearing the original sound at the same time, you'll definitely think that the two are the same, although they actually aren't. And there's no way you could ever make a human listener perceive the two souds as different. There's one important thing that you only mentioned very briefly, in fact so briefly that one might think you omitted it. If you make a kind of allpass filter where everything that's lower than f Hz is phase-shifted by 180° (while the upper frequencies stay unchanged) and you run your sound through that, then you may sometimes find the sound slightly different from the original. But that's NOT because of hearing absolute phases. It's because of the fact that the phase relationships have changed. If the frequency of f-200 originally had a phase shift of -70° and the frequency of f+100 originally had a phase shift of +10°, then it means that their initial phases differed by 80°. However, after applying the filter, the phase difference becomes -100°. You see? This is why we may find the result sound different from the original. Because the phase differences are no longer the same. And if you tell me that you did indeed mention that, I feel obliged to repeat that it was not emphasized enough to sound significant.

5:19 I can hear a difference, one that's quite obvious to my ears when switching on and off. To my ears, it seems that when the plugin isn't bypassed the low end of your voice becomes more apparent. The whole sounds maybe a bit more muffled and I'd say the low end of your voice sounds less "tight" or "controlled". If I were to hear them in isolation however, I don't think I would be able to tell a difference. I'm a VO artist, so my project usually contain only a single track, so the cpu usage isn't much of an issue. If I run a pretty hefty hpf or an instance io pro mb, I usually prefer the sound of linear phase slightly. If my hpf is especially high, I like running it in linear phase so it leaves me more headroom in any dynamics processors or limiters. Luckily Pro-L2 can account for this, but not all the plugins in my chain can.

I can't listen any difference with the phase shift on your voice (Headphones connected to my laptop here), but I can listen it, sometimes, in my studio with some tracks. It was once quite obvious when I tried it while mastering a Toy Piano recording but didn't do any blind test, so I could be wrong here. My monitoring setup has some Phase Correction Filters in my Repaer Monitoring section so I can enable and disable the phase correction quite easily. KH310 speakers. Edit: Ok, you ask about what differences we listen, in that Toy Piano project, the differences where in the transient response. When having different phase responses in L vs R (As in Slick EQ Dual Mono Phi button) the difference becomes quite more obvious as our ears are tuned to pick timing diffrences between them. Finally: My guess about that drastic ringing in the IR of the minimun phase filter; maybe that's because that sudden impulse has, is in fact, lot's of content around 22Khz, and that's where the filter is doing it's work, so thats the frequency with most audible ringing. A worst case scenario in a frequency that tipicalliy will have much less energy and is quite inaudible May it be?

Watching youtube videos NOT on your phone is such a good way to go. Anyway, I do know of people who can hear transients being off of the beat. It's something that I haven't acquired the skill to listen for yet, but I do know of people who are able to hear some 1-2 millisecond issues and know that elements aren't matching up the way they should be. Perhaps that skill transfers to being able to spot weirdness more reliably with phasing issues?

Headphone listener here To me it sounds like a bass boost when the eq is engaged. That was when it was just your voice. With the mono and stereo mixes it sounded like the audio was canting in the direction of the channel with the eq active.

Hopefully one day ill understand some of this witchcraft

While the difference is subtle I can definitely hear it in the A/B test with your voice in minimum phase mode. With it on it sounds almost like the lower frequencies around 500hz are being distorted slightly, causing some harmonics to be created. It honestly reminds me a little bit of a low-quality audio codec, but again much more subtle. While I can't tell you exactly why this is, that's just what I hear.

View & Like solely for the thumbnail. 😁👍

For the video to do well you need to have a shocked face and a bunch of random arrows in the thumbnail. In all seriousness, I love your academic and logical approach to audio. There's a lot of BS bordering on superstition these days in the audio community/industry among younger folk like me.