I've checked a lot of dance music and never found anything with meaningful 20Hz content. It's extremely rare for "deep bass" to be lower than 40Hz. The only genre I can think of that often has very deep bass is pipe organ music.
EDIT: Movie soundtracks also commonly have <40Hz content for sound effects.
It’s news to me that one might need 20Hz for purely an audio track, especially in the home. I would understand at a concert or something but to demand it from a single small self-contained unit like that sounds like looking for love in all the wrong places.
I wonder if the "undertone series" for a bass hits this, since a low E on a 4-string already is at the ~40hz range. Definitely something that's felt, more than heard, as you mention.
Pink Floyd- Dark Side of the moon. The Heartbeat in the introduction contains significant energy in the 20-40hz range
Bass Mekanik- Each of his releases includes some music but also features a test section which will play frequencies with labels as to their frequency. Even if this sort of music isnt your thing it is helpful if you are curious as to what the frequency response of your stereo.
Tchaikovsky 1812 overture- Cannon Blasts go sub sonic.
>Apple uses Balanced Mode Radiators (BMRs) instead of industry typical tweeters. They have a response range of ~250Hz-20kHz, whereas typical tweeters have a range of 2kHz-20kHz. Here is gif of a BMR compared to other speaker technologies 
>Apple applies Equal-loundness contours to equalize absolute energies of loudness to perceived loudness by the human ear. That is, the dB of sounds in the 2KHz-5KHz is decreased by several decibels, because the human ear is more sensitive to them.
>They recommend putting the HomePod on a small stand (5 in), because even the room correction processing Apple is using is unable to compensate for echoes that originate so close.
>There is apparently some agreement within this community, at least, that if Apple made a HomePod Plus with a larger subwoofer to allow reproducing sounds down to 18Hz, they would essentially beat the entire high-end audio market.
 - https://gfycat.com/BiodegradableNiftyKoala
 - https://en.wikipedia.org/wiki/Equal-loudness_contour
I would expect recorded material to already account for this. Does anyone know why Apple finds it needed to further apply sound shaping to recorded sound?
(That is, I would expect audiophile-grade equipment to best mimic the monitors on which most recordings are mixed, which presumably is a flat loudness curve.)
A lot of songs are mixed with less bass than ideal, because the engineer knows that everyone and their grandma has that bass boost button permanently down on their stereo. Or people are using beats headphones that crank the low end.
The ideal mix also changes over time. Part of that is fashion. Every period has its own ideal sound. But another part is the equipment the average listener has.
Ever have a beater car with a terrible stereo? Music from the 60s will still sound great because it was mixed to sound good on transistor radios. You can hear the bass guitar even though there's no low end on your setup. Anyone who had a K car in the 90s has a love for CCR. That's a fact.
In previous decades music was mixed to sound good on wood encased speakers, which have their own resonance characteristics. For modern music, you assume plastic. You also have to assume that a large portion of listeners are going to be using apple earbuds, or some other cheap earbud.
When working on a mix, you usually have a few different speakers to choose from in the studio. But the final test is always how it sounds in a car.
A couple other commenters noted that perception-weighted curves vary with total SPL; louder sounds sound different. I had never thought about that before but that makes sense to me, that Apple would apply a dynamic adjustment that studios can't.
With fully digital players, I guess there's no reason to not have dynamic EQs that adjust along with the volume. I'd think you'd see this more often, but I guess even basic EQs aren't available most of the time, so it's just not a feature that most people would care about.
Not necessarily, because that assumes the audio was mixed correctly to begin with. The audio will have to be played back over digital and analog broadcasts with varying dynamic range characteristics, not to mention various output technologies, including $5 headphones. And not to mention how the shape of each persons ear affects the response curve in different ways.
There is no way for an engineer to produce a rendition that sounds great in all of those scenarios, making 'mimicking the monitor' a pointless pursuit to begin with - even IF you were an audiophile listening to 400MB DSD files.
>Does anyone know why Apple finds it needed to further apply sound shaping to recorded sound?
I'd say the vast vast majority of people want more to have the audiophile label/association than actually listen to music with a flat curve, because most music will sound like crap.
Sorry for the rant :P
Long and short of it is that if you turn the volume up, and your want it to sound the "same" but louder than before, you need to turn different frequencies up more than others, to account for the human ear's varying sensitivity to different frequencies.
Personally speaking, I'd take great mono over sub-par stereo any day anyway.
That said, stereo can matter, but only when the recording itself was done in stereo. Proper stereoscopic recording is pretty cool to listen to with headphones.
All my opinion, of course.
Also, I doubt most audiophiles would use it as their primary listening source, but it may be the perfect solution for additional listening areas.
If you're bouncing audio off walls you may get ambience, but you're not going to get a clean stereo image.
Also, the KEF speakers are hardly world beaters. They have a good reputation as PC speakers, but that's not setting the bar very high.
Professional speaker manufacturers like Genelec use a similar adaptive tuning system, and you can buy a microphone and software add-on to flatten the response of any speaker.
The limitations are well known. The correction curve is level-dependent, because room resonance is a time domain phenomenon created by physical standing waves in a 3D space that includes damping elements, and you can't truly correct it with a frequency domain solution.
You can approximate a time-domain correction with convolution and some assumptions about the room geometry and acoustics, but it's never going to be perfect.
Bottom line: I'm sure the Homepod sounds very nice, and - as usual - it's innovating with technology that's been available elsewhere for a while, and made much easier to use.
But it's not magic, and it's not going to sound hugely better than a much more expensive true stereo system.
Of course that'll do just fine for a lot of buyers.
Apparently there is.
"Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective. This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers (or stereo headphones) in such a way as to create the impression of sound heard from various directions, as in natural hearing."
I'm inferring from that there are other methods to create an illusion of multi-directional audible perspective.
I was surprised by the HomePod. It's much smaller than I had imagined, and sounds much better. I think I might get another one when the Airplay 2 update comes out.
today practically all new systems marketed to audiophiles are stereo, but my guess is that most would consider faithful reproduction of the signal to be more important than the number of channels if they had to pick.
That's the difference with "mainstream" companies (sony, panasonic, ...,apple?) and hifi one (rotel, nad, marantz, ...): sony will probably send the amp/speaker to production after it looks ok in measurements, while hifi companies always listen after measurement, tweak, measure again, listen, ... you get the point.
Edit: this other thread on this same post is already discussing this topic - https://news.ycombinator.com/item?id=16360296
For one, he makes the point that, for the price, you can get that amp, an Echo Dot, and build the speakers he put together... except that's the entire point. You'd have to build the speakers yourself (including soldering!), have 3 (technically, 4) distinct pieces of equipment to maintain, and you have to have that unsightly hardware and wires everywhere. The setup he shows in the video looks like complete crap to me and there's no way that I would put it out for display like that in my house. The HomePod isn't meant to be an alternative for that. It's meant to compete with other wireless speakers and, when compared against those, it's a significantly better product at a slightly higher price. It's like the "I can build a PC myself that's way better than an iMac for cheaper". Sure you can...but don't pretend like it's the same quality, form factor, ease of setup, or any multitude of reasons why the price differs from a DIY solution. That's not the point here.
The other thing that bothered me is that he tested it in a studio with sound insulation on the walls and then complains about the audio and balance, saying that it's very bass heavy. Again, this isn't what the HomePod was designed for. The mics and the processor are specifically meant to listen for acoustics and reflections and use those to set up the soundstage for the speaker. He's taken all that away and then complains that it's too bass-heavy. Of course it's too bass-heavy! He removed the entire mechanism by which the HomePod determines its output!
Now, I'm sure everyone will be quick to point out that he moved it into his bedroom as if that's a good example of his objectivity. I would agree except that he then doesn't objectively assess the HomePod. He, again, compares it (which he says he set up on his nightstand or table) to his custom-built speakers that are mounted to provide directionality to his sweet spot. He's starting from a non-neutral reference point, comparing to something that the HomePod is not even attempting to be a comparison to, and then pretending to make the objective assessment that it's lacking. Of course it's lacking! It's also lacking when compared to my home theatre setup. That's not really a fair assessment. If he had put an actual Echo on the same nightstand/table and then compared them, I'd find that fair.
Again... I think the HomePod is really just a wireless speaker that is significantly higher quality than what you'd normally get from a wireless speaker at a slightly higher price. As an audiophile, I like it much better than my Echo, my Sonos, or the little Bluetooth speaker that my wife has for obvious reasons. Of course I can build something that sounds better for that amount of money. That's not the point. I'm not going to be able to put together what they did in the package they did for that money without a ton of hassle. That's where the HomePod is worth it to me. YMMV.
(Of course this is completely impractical for almost everyone, but I'm talking about some platonic ideal of audiophile)
With amps, specs only take you so far, once you get above the absolutely dirt cheap crap it doesn't really help. Using THD as one example, above 1% might indicate something wrong with the amp design... bellow doesn't really make any difference because these are just tested with sine waves (do you listen to pure sine waves? no), very low might even indicate that the design has been compromised just to get good paper specs.
Headphones and speakers can be similar, frequency range doesn't really tell you anything unless they are severely limited and thus it only really helps sift though crap.
You are correct about reviews though, it really depends on who is reviewing it, and 99.99% of the people out there have hardly anthing worth comparing what they are reviewing it to. If i've never had a pencil before, and I get a pencil and it's all crumbly I will be like "It's frickin amazin, it makes marks on paper", but that doesn't really help anyone else trying to make an informed decision. Additionally, even if you start going through audiophile forums and vet authors for their background knowledge, _even then_ you have the aspect of personal taste, musicality etc.
So yeah... if you want good audio, your fucked :) the only way is to try. And try not to go crazy. But not buying stuff with any integrated digital nonsense is a good starting point.
It's not repeatable, and I don't know what units of measure could be used either.
"I also paid full price for this HomePod, with my own money. I paid for all the equipment to measure it with, and I own every speaker in featured in this review."
This is very clear too:
"Neither KEF, nor Apple is paying me to write this review, nor have they ever paid me in the past."
This wasn't necessary, in my opinion, but again is very open:
"At the same time, I’m a huge apple fan. Basically, all the technology I own is apple-related. I don't mind being in their ecosystem, and it’s my responsibility to tell you this."
It could be just to make the review feel more authentic, and also both advertisers and audience are getting smarter.
This is not a statement about this particular reviewer, just my thoughts.
First off: This guy is talking about "measurements" not perceptible quality, and anyone who has reasonable experience in audio quality will know that amp specs and measurements have almost zero correlation to audible sound quality and musicality (THD anyone).
Second: An all in one active load-speaker this small, singular and low powered will never sound "good" compared to the same money spent on actual audio (a basic integrated amp and some bookshelf speaker).
These types of devices are always a bag of compromise for audio quality, in the form of "everything must be small" (speaker diaphragms and drivers suffer because you need both large and small ones to comfortably reproduce the frequency spectrum without seriously fucking with the audio signal), battery powered (D-class amps), and finally mono for some bizarre reason, because who cares about sound anyway.
Having purchased the HomePod, it's noticeably better than the bookshelf speakers I own (AudioEngine A2+ and Odyssey LES).
It also sounds as good as my Vizio soundbar/subwoofer combo, though I've not compared it at high volume or with movies.
It is, not unexpectedly, vastly better than my battery-powered BeoPlay P2 Bluetooth speaker.
I'm very impressed.
I've no doubt many people will be impressed, it's all relative. But if you actually care about audio you could have bought a lot more for you $300 or whatever it is, but then people don't buy these types of things for audio, they buy them for integration.
The fact that you are comparing it to a "soundbar" shows that you probably haven't heard much better. (i'm not trying to be nasty, it's just true of most consumers, we are not living in the HiFi age anymore).
Comparing the HomePod to a class A amplifier is nonsensical. Nobody is pretending it's competing with that segment.
None, I'm not considering those features, only audio quality.
> Comparing the HomePod to a class A amplifier is nonsensical. Nobody is pretending it's competing with that segment.
The author is implicitly:
> The HomePod is 100% an Audiophile grade Speaker
Your absolutely right, it is nonsensical, it's _physically_ in a different class all together. The author has gotten out his spectrum analyser or whatever and measured a relatively flat frequency response of a sine-wave and concludes... this is good audio: Except, "No" says every amplifier and speaker designer ever.
I've got one or two respectable 2-channel audio systems around the house (although I remain solidly in the "cables matter almost not at all + the room matters a lot" camp) and am willing to consider that Apple may have produced a very nice-sounding active speaker for $350 a pop if they decided to. Consider how much more manufacturing scale and tech reach Apple has, compared to, say, Dynaudio or a boutique room correction software shop. Give it a fair shake before remounting the audiophile high horse.
Yes, it was just an argumentative counter example to the Class-D amp that will inevitably be used by this item.
I don't expect you to be convinced by me, but maybe one day you will experience some nice audio on a good system and then have a personal baseline to understand why calling something this small "audiophile quality" seems silly.
If they scale it up it could very well be truly spectacular.