[HN Gopher] EQ: A video about all forms of equalizers
___________________________________________________________________
EQ: A video about all forms of equalizers
Author : robinhouston
Score : 241 points
Date : 2025-10-18 10:51 UTC (1 days ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| olooney wrote:
| Videos don't do well on Hacker News, but I encourage people to at
| least watch the first couple minutes of this one. The
| oscilloscope visual overlay is interesting and the editing is
| really good.
|
| Also, given the topic (audio equalizers) there's no way it could
| have been a blog post.
| IndySun wrote:
| Good point. The bandcamp link to Posy music is equally
| pleasant. Nice to find actual mellow music.
| creer wrote:
| I would hope mostly what doesn't do well is useless titles -
| like one word, or a pithy joke that makes sense only in
| retrospect. Unfortunately there is also that guidelines which
| discourages doing better.
| gus_massa wrote:
| Usually the subtitle is fine:
|
| > _A video about all forms of equalizers. From one-click bass
| buttons to advanced studio correction._
|
| That can be reduced to:
|
| " _Equalizers: From bass buttons to advanced studio
| correction._ "
|
| PS: I'd try to keep the original title too, but in this case
| it doesn't look nice
|
| " _EQ: Equalizers - From bass buttons to advanced studio
| correction._ "
| cwillu wrote:
| It's pretty common for blog posts in this arena to just include
| samples that you click to play.
| nutjob2 wrote:
| Videos are harder to watch at work since it's obvious they're
| not work related compared to blog posts.
| layer8 wrote:
| Also the hardware presented is just gorgeous.
| mock-possum wrote:
| Ah but I'll always make time for a Posy video
| IndySun wrote:
| A pleasant, if muted, layman's 10 minute journey to explain
| sound, eq, and speaker response. It gets juiciest on room eq
| correction/compensation, approaching the 9 minute mark.
| kragen wrote:
| I'm not sure Posy is a layman.
| moffkalast wrote:
| Afaik the dude is a professional audio engineer with a retro
| soundsystem hoardin.. ahem, "collecting", hobby.
| unkeen wrote:
| He's decided to collect no more than what fits into the
| white cabin.
| moffkalast wrote:
| And other fun jokes he tells himself ;)
| IndySun wrote:
| >I'm not sure Posy is a layman
|
| I mean/meant pleasant for average (layman) interest. A
| compliment, in other words.
| tverbeure wrote:
| Very first sentence: "This is pink noise... if you measure it,
| you can make it look like a straight line."
|
| He then shows a horizontal straight line: that's white noise?
| lelandbatey wrote:
| Pink noise distributes energy logarithmically in a way that
| matches the the sensitivities of the human ear. The graph which
| he shows on screen is ALSO in that same logarithmic space,
| hence why it shows pink noise as flat: it's flat as far as how
| humans hear it. White noise is not perceptually flat to humans.
| Thus when testing audio, it's important to use pink noise
| instead of white noise.
|
| https://en.wikipedia.org/wiki/Colors_of_noise#Pink_noise
| tverbeure wrote:
| > The graph which he shows on screen is ALSO in that same
| logarithmic space, hence why it shows pink noise as flat
|
| Does this also mean that audio equipment in general will
| display a spectrum with this kind of logarithmic offset
| adjustment?
| mjr00 wrote:
| More often than not, yeah. On the music production (rather
| than listening) side the two EQs and spectrum analyzers I
| use most frequently, FabFilter Pro-Q and Voxengo SPAN, both
| use a 4.5dB/octave tilt by default. You can adjust it, but
| I've never done so.
| Acen wrote:
| Practically all of audio land is logarithmic.
|
| The orders of magnitude in power/loudness is pretty
| astonishing.
|
| When introducing decibels to new audio engineers, we
| generally introduce it as a 3db increase is a doubling in
| power, a 10db increase is a 10x increase in power.
|
| It gets silly when you start talking sound pressure level,
| because how people perceive a 10x increase in the output
| power, is about a doubling of the perceived loudness.
| Acen wrote:
| The main difference between white and pink noise, is white
| noise has the same level of power across all frequencies.
| Whilst pink noise has the same level of power across an octave.
|
| There are more frequencies in the high-range, so it naturally
| sounds considerably higher pitched.
|
| i.e. a C6 on a keyboard sits at around 1Khz (1046.502 to be
| exact) and a C#6 is 1108.731 KHz (a difference of 62.229 Hz)
|
| While a C3 is 130.8128, and C#3 is 138.5913 (a difference of
| only 7.7785 Hz).
|
| Then using an entire octave as an example, C3 (130.8128) to C4
| (261.6256) = 130.8128 (0Hz up to C3)
|
| vs C6 (1046.502) to C7 (2093.005) = 1046.503 (0hz up to c6 +-
| 0.001hz)
| esafak wrote:
| In the 70s/80s every home stereo system -- racks of stereo
| equipment stacked a meter high -- had a dedicated equalizer. It
| was not just for audiophiles!
| billfor wrote:
| There was a company called DAK in the 80's that sold all sorts
| of interesting stuff and I still use my BSR EQ-3000 which is an
| equalizer with a spectrum analyzer display fed by a microphone
| that you walk around the room with to confirm your settings. It
| even has a pink noise button that injects that into the amp so
| you have a uniform pattern to equalize. Sort of like an analog
| Sonos Trueplay I guess. We could do all of this in the 80s :-)
| SanjayMehta wrote:
| I built my own 10 band equaliser using instructions from
| Elektor (I think) back in the 80s. The dream was to acquire a
| spectrum analyser but real life intervened.
|
| Not sure when I even powered up my stereo system. Probably
| doesn't even work now.
| JetSetIlly wrote:
| I suspect HiFi culture was slightly different in different
| parts of the world.
|
| In my part of the world, the original HiFi guys rejected the EQ
| units. I was influenced by that I think (my father was an
| original). I still have a metre high stack of HiFi, in almost
| daily use, and have never felt the need to have an EQ unit.
| BlaDeKke wrote:
| This is a fantastic yt channel!
| adzm wrote:
| Highly recommend their lightbulb video as well.
| encom wrote:
| Posy is just one guy.
| unkeen wrote:
| Although he has at least two personalities. Sorry. Sorry.
| BlaDeKke wrote:
| This is my favorite: https://youtu.be/eGQQWIbD-nM?si=CtQ-
| MPIxx8h3vYxH
| sideeye wrote:
| My favourite is the Mouse Cursor video
| https://www.youtube.com/watch?v=YThelfB2fvg , I install
| them on every computer I own.
| evantravers wrote:
| I knew this was a Posy video before even opening the link.
| activexray wrote:
| I love Posy's channel so much. Really beautiful love letters to
| all kinds of vintage tech (plus his own music!).
| franczesko wrote:
| I tried to post Posy's videos a few times here, but with no
| bigger interest.
|
| His videos about LCD technology are hypnotizing. Bonus - he makes
| all the music.
| mrheosuper wrote:
| His video always scratch a part of my brain that i event dont
| know it exists.
| ggm-at-algebras wrote:
| The history behind vU meters is also fascinating. People used to
| calibrate off the BBC techs, or off American techs.
|
| No BIPM, no SI units: what the BBC say.
| ZeroGravitas wrote:
| For the earlier systems with the bass boosts, are the graphs
| showing what comes out of the cables or what comes out of the
| speakers?
|
| I would assume they don't care about the very low bass because
| they were designed as a unit and physically couldn't produce
| those notes very well anyway. Hence the need to boost slightly
| higher frequencies to fake bass.
| whstl wrote:
| The straighter lines are what comes out of cables.
|
| The more squiggly ones later (eg: 2:45) are what comes out of a
| speaker. But since he uses a microphone to measure the
| speakers, so that measurement will also come with room sound.
| He would need an anechoic chamber to measure "only the
| speaker".
| Aldipower wrote:
| Couldn't hear this video, just watch, because I have no sound in
| the env I am currently in. But some thoughts about EQ.
|
| "EQ isn't phase shift, phase shift is EQ.", a video title I saw
| once, but hits the nail on the head.
|
| "Nothing is for free.", if you eq some frequencies, you affect
| some other frequencies too. You can use this to your advantage,
| if you are aware of this.
|
| "EQ graphs are lying." Lack of resolution and not revealing the
| phase shift makes most stock EQ graphs not telling the truth.
|
| "My hearing aids sound strange/metallic." This is the phase
| shift, you are hearing.
|
| Have a nice Sunday everybody!
| rock_artist wrote:
| I think the title on HN is misleading. Sadly I'm not sure what's
| the short and clearest title :(
|
| The video is very nicely made and it focus on sound systems /
| boomboxes frequency response and behavior of included filtering
| modes.
|
| So when talking about EQs with "all forms" in mind, you should
| consider:
|
| - EQ is merely combination of one or more filters.
|
| - There are many common filter designs, the video isn't about
| that, it also doesn't mentioned Low-pass/High-pass/band-pass/bell
| or common structures, but it is only showing them.
|
| - Filters made and behave differently
|
| - Most filters (including the ones in the video) are done on the
| time domain (vs spectral one)
|
| - Phase, this is the biggest missing piece in the video imho.
| Naive filtering is "smearing" the signal to achieve the different
| tone balance. By doing so, they also most likely change the phase
| (unless using linear phase filters)
|
| - Filtering might result delay in time.
| atoav wrote:
| You have a slight misunderstanding here about the phase shift
| bit.
|
| Technically filters don't cause phase shift, phase shift causes
| filters.
|
| That means in the analog world _all_ realtime filters come with
| phase shift, if they didn 't you wouldn't have a filter.
|
| In the digital world there is a thing called linear-phase mode
| where clever people found ways of building filters that shift
| the phase of the _whole_ signal the same way (involves running
| the signal through forwarwards and backwards through special
| filters). If you now have an audio program that deals correctly
| with the latency introduced by each effect, you can shift the
| rest by the same amount meaning you bought yourself a linear
| phase response with added latency (a small delay) on
| everything. Remember: Humans can 't really hear phase smears
| unless they happen in relation to another thing that is in
| phase. This only happens when you mix two signals. The result
| of that mix is yet again a filter (e.g. comb filters).
|
| With filters everything is a trade off all the time, but again
| phase shift is not a just a bad side effect of a filter, it is
| the mechanism by which it does the work. And sometimes the
| phase shift introduced cannot be heard.
| Aldipower wrote:
| And also linear phase isn't for free, besides the latency, it
| also adds pre-ringing, which especially in the lower
| frequencies can be very audible and annoying.
| atoav wrote:
| There is no such thing as free lunch after all.
| Aldipower wrote:
| I once saw a place with free beer, then I woke up.
| Sesse__ wrote:
| FWIW, you don't need to run forwards and backwards to get
| linear phase. Any symmetric FIR filter will do.
| rcxdude wrote:
| Yeah, there's a difference between linear phase (which you
| can achieve with a causal filter, i.e. one that is running
| in real-time) and constant-phase, which requires that you
| have more or less the whole signal before you filter it
| (you can approximate it to the extent you're willing to add
| more latency).
| atoav wrote:
| Good addition.
|
| I mentioned the forward/backward bit as this was a way to
| achieve linear phase in analog times eith more conventional
| filters (although the cost here was even higher with the
| additional added noise floor due to tape noise ad the extra
| work involved).
| JKCalhoun wrote:
| > Phase, this is the biggest missing piece in the video imho.
|
| It's why I like full-range speakers--no crossover. At most you
| might throw a cap on a super-tweeter (yes, even so-called full
| range need help on the top and bottom ends of the spectrum--so
| super-tweeters + sub-woofers). Complicated crossovers destroy
| the phase.
|
| Without crossovers/EQ the more stripped-down full-range setup
| preserves what the Hi-Fi nerds call "soundstage". (A good full-
| range setup: imagine the "soundstage" you get from wearing
| headphones--but without wearing headphones.)
|
| Those seeking a full-range setup (especially with a tube
| amplifier) are kind of adjusting for EQ simply by the type of
| speakers/drivers and placement. (And to be sure they're not
| going for a flat, studio-monitor response but what _sounds
| good_ ).
| GistNoesis wrote:
| Can measurements and calibration be done easily at home to see if
| your sound system is well calibrated ?
|
| I was thinking of playing a pink noise on the speaker and
| recording it with a cheap microphone or displaying it with the
| Spectroid app, but the microphone probably has it's own frequency
| response.
|
| Is there an App for that ? With each phone model microphone
| factory calibrated ?
|
| Is there a way to use known fact about physics like harmonics
| should have a specific shape (timbres) that's should help
| equalize frequency with respect to each other ? Or from various
| microphone positions, calibrate it so that any cheap microphone
| can do the trick ?
| LM358 wrote:
| A UMIK-1 is pretty cheap these days. Also check out REW.
| scns wrote:
| > but the microphone probably has it's own frequency response.
|
| Spot on. When you buy a measurement microphone, you can
| download it's specific response from the manufacturer.
| behringer wrote:
| It's harder than that, because your ears have their own
| frequency response that can only be measured by your
| consciousness.
|
| I've found a lot of enjoyment in equalizing as best you can
| with hardware, and then doing the finishing touches against
| your ears.
|
| Take a frequency generator, I use a web one, and play a tone
| that matches your eq knob, and work your way through making
| sure all the tones are at the same volume. You'll have to do
| this a few times.
|
| You might be surprised at how good it will sound. Especially
| the upper ranges which will usually be far too low if you only
| calibrated with mics and hardware and not your wetware.
| KronisLV wrote:
| Oh, that's really cool, the channel seems like it has a lot of
| other nice videos as well!
|
| I wish there was a video that's so nice about compressors, like
| in Audacity you have all of these settings and most are also
| present in OBS and other software: * Threshold
| (dB) * Make-up gain (dB) * Knee width (dB) *
| Ratio * Lookahead (ms) * Attack (ms) * Release
| (ms)
|
| And I feel like visualizations can really help understanding them
| better, like: https://codepen.io/animalsnacks/full/VRweeb
| alongside maybe something that lets you loop an audio sample and
| see how different it sounds with each change. There obviously
| already are some videos and discussions and plenty of material
| out there, but I love a good visualization!
| jamesbfb wrote:
| POSY is an absolute treasure. The time and effort he puts into
| his videos is absolutely evident.
| 0xdada wrote:
| I have watched 10+ hours of lessons on compressors and I still
| don't hear it. I understand most concepts but don't use much
| compression besides side-chaining and the built-in Ableton glue
| compression.
| derriz wrote:
| I know what you mean - took me a while too. I understood what
| it does, how the parameters affect what it does and the
| mechanics of it, but struggled to "hear" it.
|
| I even bought a cheap $25 Behringer guitar compressor pedal
| to see what I was missing but it didn't help - later I
| realized that my guitar playing isn't repeatable enough. So
| this isn't the way to go.
|
| What made it click was due to an accidental mistake in my
| normal workflow - I recorded some DAW-less techno jam stuff
| using GarageBand (normally I just copy the wavs from my
| little Tascam). While playing back, I noticed that there's a
| master compressor and I started fiddling with it. With
| repetitive music like Techno and House, the difference
| between no compression and full compression suddenly becomes
| very apparent (although still somewhat subtle compared to
| other FX commonly used in music production). Also it helped
| that my recording had no compression on it - comprising just
| a raw drum machine and mono-synth.
| Aldipower wrote:
| It is pretty normal not to hear compression on material that
| already is quite compressed. But you will hear compression on
| very dynamic vocals or a snare drum, I am pretty sure.
| Slow_Hand wrote:
| That's normal. For engineers and mixers, compression is one
| of the more difficult phenomena to hear and build an
| intuition for.
|
| My advice for learning is to totally overdo the compression
| on a drum track (snare, kick, hats, etc) and play with the
| settings. Ideally these drums are uncompressed.
|
| Using a 4:1 ratio, lower your threshold all the way down
| until you're getting > 10 dB of gain reduction and then start
| playing with the attack time. What do you hear when the
| attack time is at 0 ms? What do you hear when you start to
| slow the attack time? 5 ms? 10 ms? 30 ms? 100 ms?
|
| Then do the same with your release time. Start with it set as
| fast as it will go and then start to slow it down. What do
| you hear happening?
|
| Once you have the attack time and release time feeling good
| then raise your threshold so that the compression is less
| heavy-handed (unless you like it). Set the threshold where
| the level of compression feels good to you.
| scarecrowbob wrote:
| I work with audio professionally and it took me a years to
| get a feel for dynamics processing. Like, it wasn't until I
| down sat with a nice compressor (in my case a Neve 453) and
| just did a lot of experiments, and then took my experiences
| from those experiments to my live gigs.
|
| IME, you can get a feel for what the threshold and ratio are
| doing pretty quickly, and that's probably enough to be
| useful. In broad strokes that's all you need to make them
| "work". If you have the attack set way fast, you'll start to
| hear the signal get a bit muddy.
|
| But attack and release (especially on a lot of plugins) are a
| bit funky, and I still can't tell what the knee is doing
| unless I move the knob around. And I own a couple clones
| (76kt or gold comp 2a) and a couple of distressors, and they
| sound different but I still need play around with them to
| coax them into what I think they should sound like.
| Aldipower wrote:
| The House of Kush made me compression rethink. He's the Bob
| Ross of audio. :-D
|
| https://www.youtube.com/watch?v=K0XGXz6SHco
| sdwolfz wrote:
| OK, so based on this video, I've turned on EasyEffects, added an
| Equalizer, set the input source to "Easy Effects Source" in the
| system settings, started playing pink noise, then tried to adjust
| the dials until the input looked closer to a horizontal line
| (it's very chaotic so that is hard to do).
|
| As some sections of the video highlight it ended up needing to
| dip the mids and boots the lows and highs. This is my end result
| (so far, I'm probably going to tweak this continuously):
| Preamp: -1 db Filter 1: ON PK Fc 27.782795 Hz Gain -3.36
| dB Q 1.7848856 Filter 2: ON PK Fc 49.40557 Hz Gain 1.09
| dB Q 1.7848856 Filter 3: ON PK Fc 87.85691 Hz Gain 5.04
| dB Q 1.7848856 Filter 4: ON PK Fc 156.23413 Hz Gain 6.43
| dB Q 1.7848856 Filter 5: ON PK Fc 277.82794 Hz Gain 3.76
| dB Q 1.7848856 Filter 6: ON PK Fc 494.0557 Hz Gain -1.19
| dB Q 1.7848856 Filter 7: ON PK Fc 878.5691 Hz Gain -5.54
| dB Q 1.7848856 Filter 8: ON PK Fc 1562.3413 Hz Gain -3.96
| dB Q 1.7848856 Filter 9: ON PK Fc 2778.2793 Hz Gain -2.97
| dB Q 1.7848856 Filter 10: ON PK Fc 4940.557 Hz Gain 0.3
| dB Q 1.7848856 Filter 11: ON PK Fc 8785.69 Hz Gain 4.35
| dB Q 1.7848856 Filter 12: ON PK Fc 15623.413 Hz Gain 8.7
| dB Q 1.7848856
|
| There's also an Output amp of -2.5dB that does not appear in the
| export for some reason.
|
| TUXEDO InfinityBook Pro 15 - Gen10 - AMD Laptop Speakers.
|
| It does make a positive difference (why don't they teach us this
| in school? ;) ). Please note I am music illiterate.
|
| EDIT: it looks like changing the input source has no actual
| effect, just need to make sure the internal microphone's volume
| is not muted, and have to keep system setting window open while
| doing this, maybe the microphone is no longer on when the window
| is closed?. Linux is weird sometimes.
| whstl wrote:
| They teach this in audio engineering school :)
|
| But the reason this is not widely talked about is two fold:
|
| First, because those measurements are heavily room dependent
| and they sound worse than treating a room. Because the room
| affects the sound in ways that EQ can't really fix anyway.
|
| Second, because the goal of mixing and mastering is making
| music sound good in a big variety of speakers and environments.
| yapyap wrote:
| Posy my beloved
| dusted wrote:
| My music listening speakers have two built in power amplifiers
| (one for the tweeter, one for the woofer) and have a DSP feeding
| right into a DAC, feeding right into those amplifiers.
|
| There's a control box that comes with them, and when you plug a
| calibrated microphone into that box, and put it in the listening
| position, you can get it to do some frequency sweeps, one at a
| time, then they calculate a correction curve for each speaker,
| based on the actual response of the particular speaker in the
| particular room, and program that curve into the DSP of the
| speaker.
|
| It's like night and day toggling the calibration on and off while
| listening to music.
|
| And yes, as he says, the best hi-fi is just professional audio
| gear..
|
| My music listening setup is simply a USB->AES converter box that
| feeds directly into the monitors, the monitors are a pair of
| Genelec 8050, and then the GLM box and volume knob. Never heard
| "hi fi" coming even close to it, not at the price, not at five
| times the price.
|
| Same goes for headphones, you can't get much better than the
| simple and cheap DT990 (or 770 if you want them closed), sure,
| you can pay about 10 times as much for some Sennheiser hd800s,
| and those are pretty good, and I do have a pair of HE1000se,
| which are not only cheaper, but actually sound better too. But
| I'd never recommend anyone who's not as stupid as myself to buy
| anything "above" DT990.. And yeah, I EQ my headphones with a dbx
| 231x two channel 31 band EQ, and while that's not as scientific
| as the calibrated monitors, for a headphone listening experience,
| it gets pretty good.
| scns wrote:
| You can get correction settings for headphones at [0]. Peace
| Equalizer (for Windows sadly) already contains them.
|
| https://autoeq.app
| spookie wrote:
| JamesDSP (Linux & Android) also provides this.
| n_kr wrote:
| "The best hifis are professional equipment"
|
| This is gold. I wish so many people understood and used this. Pro
| equipment is more robust and more versatile. And if you know some
| people you can get amazing used stuff at bargain prices from your
| local musicians or sound engineers. Lot of times, people I know
| (and I too, though I'm not a pro sound engineer) will help you
| choose and setup just because you showed interest in the things
| we are interested in. Beers are assumed.
|
| One drawback is that pro audio stuff may look ugly to non pro
| people. I made my wife listen to the cheapest studio monitors I
| could find on amazon, equalized with the same pink noise method
| in this video, and compare it to her bose and marshall speakers.
| She liked the sound better but my speakers are "yuck ugly" :(
| jama211 wrote:
| They might look ugly to pro people too, just in a studio it's
| function over form. However at home I'm inclined to agree that
| it being pleasing to look at is important to me.
| pfdietz wrote:
| Is equaliser an alternative spelling, perhaps in British English?
| I ask because there's a _mathematical_ entity called an
| equaliser.
|
| https://en.wikipedia.org/wiki/Equaliser_(mathematics)
| nativeit wrote:
| Posy's videos are always incredibly creative and beautiful
| celebrations of retro tech.
| Archit3ch wrote:
| From the title, I expected Neve and Pultec, not 90s HiFi and
| digital EQs. :(
| amelius wrote:
| These graphs show only amplitude, not phase shift.
|
| Looks like an incomplete approach if you ask me.
| ZoomZoomZoom wrote:
| The second sentence in the video hides a bit of complexity. Pink
| noise isn't a straight line on the spectrum analyzer unless a
| correction slope is active, and the common settings for the slope
| (3, 4.5) are just a convention.
|
| I guess, that's why it says "you _can make_ it look like a
| straight line ".
| jama211 wrote:
| I saw this earlier today and it was wonderful, dude has a great
| sense of humour too
| Humbly8967 wrote:
| EQing for a flat in room response is NOT ideal!
|
| Correcting a speaker requires measuring the *anechoic* response,
| and only the bass should be tuned to subtract the room's effect.
|
| This video [1] provides a crash course on science of audio
| reproduction.
|
| [1] https://www.youtube.com/watch?v=zrpUDuUtxPM
| Slow_Hand wrote:
| Yes. I work for a company that tunes dozens of speaker systems
| in high-end recording studios a year and our target frequency
| response balance can generally be described as this: A spectral
| "tilt" in which the bass frequencies are +6 dB louder than the
| highest frequencies. The slope downward should be gradual, from
| lows to highs. Again, with a 6 dB difference between the bottom
| and the top octaves.
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