back to article Five ways Apple can fix the iPhone, but won't

Apple's new iPhone will be packed with new features you didn't know you needed. It almost certainly won't be getting features it absolutely does need. We made a list of what Apple needs to do, but won't. 1. Two-day battery life Apple’s obsession with making the iPhone as slim as possible means that when you buy an iPhone the …

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Sound

Try this one then:

https://www.hk.onkyo.com/Product/GRANBEAT_DP-CMX1/index.html

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Anonymous Coward

Re: Sound

You need to read up on the falsehood of showing digital sound as 'stair steps' and why 24bit audio is meaningless to so called 'hi-def' sound. As a way to get fools to part with money then it makes sense.

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Re: Sound

Why on earth would you link, without comment or explanation, to a Chinese (Japanese? Korean?) website on a UK-based, English language news forum? How many people do you really think that is going to be useful for?

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Re: Sound

For a premium product such as Apple not to provide a good DAC is just cheap. What you hear depends on 3 things, your ears, the quality of the original recording and the Device(s) used to playback, Apple is just proving its fiduciary duty to maximize shareholder profits has made them short sighted.

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Unhappy

Re: Sound

"For a premium product such as Apple not to provide a good DAC is just cheap"

About the only bloody thing that is cheap with Apple!

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Anonymous Coward

Re: Sound

Monty

16 bit, 44.1kHz isn't an arbitrary playback standard. It's chosen to match the capabilities of the human ear - the complete capabilities of the perfect human ear.

There is a place for higher bit depth and a place for higher sampling rates - but playback isn't that place.

You need an extra set of crossovers, amps and speakers to handle the ultrasonics that we can't hear in order for them not to actively degrade the signal we can hear due to harmonic distortions (which you could have simply encoded into the 16/44.1k signal if you wanted them).

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Re: Sound

I diasagree.

First, I can hear the difference. Yes, I have tried blind testing, and with excellent earphones I can tell the difference, while saying "yes, the difference is very small to my ears."

I can tell the difference up to 48Khz, 20bit. Depending on age, some people might not benefit from sample rate.

The reason you do this (24 bit, 96K) as you probably know, is to preserve the quality while processing the sound.

Then you downsample to the desired quality. CD quality is a bit too low.. 20bit 48Khz is about perfect.

Now, on a portable device I do understand the need to compress beyond lossless into lossy.. the music otherwise just wont fit.. but to provide a pathetic DAC only makes the sound worse.

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Re: Sound

"First, I can hear the difference. Yes, I have tried blind testing, "

Unless you've tried supervised double blind testing then there is no point in the conversation.

If you *can* tell the difference - then I'd love to set up a double blind test for you - I have the hardware to give you up to 24bit 48k...

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Play back depth is a red herring...

...But these Sabre DACs sound very good.

The 24 and 32 bit DACs fitted to, amongst others, some LG, HTC and Sony phones sound very good indeed - but not because they can handle 24 bit audio per se. They sound good because care has been taken by ESS in their design and manufacture - and they are mated with a good amplifier that can drive a large variety of headphones. Having gone to that effort, they may as well be made to play back any file natively, so it's better to say they are 32 bit because they sound good, rather the other way round.

Still, it's a moot point if you are using headphones with their own DAC, or merely using the phone as a remote control for a device like a Chromecast or Sonos. Good headphones should last you over several generations of phone.

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Re: Sound @Speak no Evil

Apple is just proving its fiduciary duty to maximize shareholder profits has made them short sighted.

Why is that short sighted? The number of Apple customers who even know what an audio DAC is will be small, those who KNOW that the DAC is a cheap commodity spec is smaller still, the proportion of those who care is yet smaller, and I am confident the number who will defect to Android because of it is utterly insignificant.

What's more, although I'm firmly in the Android camp (enjoying a 24 bit hi-res DAC on my £150 grey import, snark, snark), but even so I can confidently bet that the number of audiophile refugees fleeing Apple and seeking asylum in Android will be a tiny, tiny fraction of those moving the other way because they are pissed off by Google and handset makers' persistent cavalier attitude to software updates and privacy, along with relatively poor hardware support from most phone makers.

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Re: Play back depth is a red herring...

Good headphones should last you over several generations of phone.

You've not met my kids, I see. The Sony ZX330 cordless headphones are lasting very well, but anything with wires lasts about two months.

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Anonymous Coward

Re: Sound

@AndyS It's Chinese, the .hk. in the link should have been a give away that it's Hong Kong. That said, it was lazy of the OP since the English page is right here https://www.hk.onkyo.com/en/Product/GRANBEAT_DP-CMX1/index.html.

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Re: Sound

Apple already explained why. They have said for a while now that better DAC's are available outside the phone, so rather than lock the consumer into what ever DAC the phone ships with (often chosen due to cost) the consumer can connect to the phone via Bluetooth and use the DAC on their third party device instead. It's one of the reasons for ditching the 3.5mm jack.

Maybe el reg where taking the piss with the DAC thing, or just baiting people, providing them with something to moan about, either way the DAC in the phone is now irrelevant.

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Re: Sound @SpeakNoEvil

I'm not persuaded I agree on DACs: I don't actually agree with the decision to remove the headphone socket but given that it's gone, the only analogue output a modern iPhone has is its built-in speaker. You're not going to get any benefit out of putting in a good DAC for that.

Incidentally, I checked: third-party DACs are available. You don't have to use the $9 one Apple sells. For those with a real love of cables, USB DACs like the Dragonfly are usable via the lightning to USB adaptor.

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Re: Sound

> I can tell the difference up to 48Khz, 20bit

It's far more likely that you're hearing the differences between the quality of different DACs than the underlying sample rate or depth.

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Re: Sound

"16 bit, 44.1kHz isn't an arbitrary playback standard. It's chosen to match the capabilities of the human ear - the complete capabilities of the perfect human ear."

Nope. It was chosen to match the vertical-blanking insertion period used by 60Hz U-Matic videotape equipment. In the late 1970s, it was the only affordable recording medium with the bandwidth to hold a CD master, so it dictated the sampling rate. ( https://cardinalpeak.com/blog/why-do-cds-use-a-sampling-rate-of-44-1-khz/ )

So, that gives a maximum reproducible frequency of 20.05 kHz. While it's true that few humans can sense audio signals over 20kHz, there are many steps in the chain of reproduction that make 44.1kHz not quite good enough to reproduce the full audio spectrum, especially if you wish to provide a stereo signal.

First off, Before you can get any kind of digital signal, you need to encode it. That means sampling. However, before you sample a signal, you need to remove any signal components whose frequency is too high for you to sample. If you don't do this, you get aliasing, and a worthless digital input (https://en.wikipedia.org/wiki/Aliasing). Thing is, the analogue filters you need to do this removal of un-sampleable signals do not have a perfect on/off response - in effect, if you want a filter that will pass frequencies of, say, 16 kHz, you may also have to allow allowing frequencies as high as 25 kHz through too, because they're still within the tail-end of the filter's "pass band". You can make that cutoff sharper, but it can create "ripples" in your pass-band, and/or allow higher frequencies through again (analogue filter design is a special kind of hell...). But, if you were to raise your sampling rate to 48kHz, then you've got at least 4kHz of headroom above the highest frequency you need to preserve.

Down-converting a multiple of 48kHz to 44.1 kHz is possible, but if it's not done correctly (and it often isn't), it introduces similar artefacts to the aliasing problems during sampling.

The second reason for higher rates is for better preservation of signal phase. The human auditory system uses phase differences between higher-frequency signals to determine spatial positioning of sound source, but phase and amplitude interfere with each other in digital sampling systems as you approach the maximum permitted signal frequency. The extreme case is that a signal with a frequency of half your sampling frequency will not register at all if it is 90 degrees out of phase with the sampling signal (the sampling points would fall on the zero-crossings of the input, so you get 0,0,0,0,0... as your output). With mono, phase isn't usually an issue, which is why most sampling tutorials gloss over it; with stereo, phase accuracy is very important.

The third reason is that most modern replay equipment processes its signal before converting it back to analogue. Equalisation, driver response correction (as used in "direct digital" speakers and headphones), room parameters, delay, noise cancellation and dynamic compression all happen on the digital signal, but all take their toll on the output. If you start with more information, even if that information is not audible, the accumulated errors from DSP will still be in the inaudible part of your signal (you don't get the same benefit by simply "upsampling" to 192KHz/24-bit before processing, because upsampling itself cannot add information; in fact, it removes it).

Finally, your hearing isn't linear, but PCM audio is. 16 bits is about 100 dB of dynamic range, but your hearing has about 130 dB of dynamic range, albeit with a non-linear response. You could use non-linear PCM to extend the same 16 bits over a wider range of amplitudes, but that means non-linear DACs, which are much harder to make than linear ones (and it can increase audible distortion where high-amplitude, but very low frequency, tones are overlaid with higher frequency tones - as often occurs in music). It's easier to just use more bits, and capture the full dynamic range of human hearing.

With lossless coding, high bitrate audio doesn't take very much more space than 44.1/16 (mainly because of the signal is only 0-24 kHz), and as it makes improved reproduction much simpler to implement, there are plenty of reasons to prefer it to 44.1.

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Anonymous Coward

Re: Sound

"Maybe el reg where taking the piss with the DAC thing, or just baiting people, providing them with something to moan about, either way the DAC in the phone is now irrelevant."

I have no clue why you were downvoted.

It seems many people don't understand that the 3.5mm jack was the 'A' in "DAC" (it means "Analog", remember?). Without the jack, there's no point in converting digital signal to analog ones inside the phone anymore.

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Re: Sound

"Finally, your hearing isn't linear, but PCM audio is. 16 bits is about 100 dB of dynamic range, but your hearing has about 130 dB of dynamic range, albeit with a non-linear response. You could use non-linear PCM to extend the same 16 bits over a wider range of amplitudes, but that means non-linear DACs, which are much harder to make than linear ones (and it can increase audible distortion where high-amplitude, but very low frequency, tones are overlaid with higher frequency tones - as often occurs in music). It's easier to just use more bits, and capture the full dynamic range of human hearing."

Ignoring the rest of your post, since it is talking about the mastering aspect of audio, which is where there is a benefit in higher sample rates - and demonstrates confusion over things like nyquist frequency, and the accuracy of phase information in a sampled signal...

Although you do seem unaware that even a 44k ADC will oversample like mad in the first phase, and then downsample afterwards, so that it can use a cheap digital filter with a far sharper cutoff than an analog filter could provide. Although I am really intrigued as to why you think that a correctly upsampled signal will 'lose' information...

PCM is linear, but it doesn't have a lowest signal of 1bit. You can quite happily encode a signal with an amplitude well underneath 1 bit with appropriate dither. This is demonstrated in the video linked above.

The other thing is that the ear isn't actually capable of 130dB range.

It is, but not rapidly. We actually use a much lower range than this because the muscles which adjust the effective amplification from the bones in the ear don't release quickly (similarly to the way it takes ages to get night vision, and no time at all to lose it).

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Facepalm

Re: Sound

A load of old pish!

People arguing over bitrate and DACs, the average punter puts on Girls Aloud or some such other shite while they're texting, ironing, farting or whatever so putting in shit-hot audio tech in a phone is a waste of time and investment. When I listen some bunch of spotty twats blasting out some utter bollocks (c)rap music on the train through the tinny little phone speaker that makes it sound like a wasp in a drinks can, then I can only imagine you audiophiles, with regard to mobile phones, have way too much free time on hands for this sort thing!

Note I said mobile phones, top notch, pro studio audio kit is no laughing matter, but we're talking about mobile phones with pissy little tweeter that couldn't play an amplified gnats fart! Some things are worth arguing about, this really is not!

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Re: Sound

and demonstrates confusion over things like nyquist frequency, and the accuracy of phase information in a sampled signal...

I can't see how you came to that conclusion - the problem of phase affecting the recorded amplitude is well known and pretty easy to demonstrate, and it is significant when your goal is fidelity of reproduction, rather than simply producing an intelligible signal. Phase differences in high frequencies between the Left and Right signals are the whole reason stereo recording works at all, so it's a very important factor.

But really the point I was making was that there's nothing special about 44.1k / 16 bit, and that without the particular constraints that existed at the time, the industry would have gone with higher bitrates. Particularly, that 44.1k sampling rate was a result of the need to create masters affordably, rather than any solid engineering analysis of the problem. It's telling that every subsequent format has used a base rate of 48kHz or a multiple thereof.

If 44.1k at 16 bits had been "perfection", there wouldn't have been such an immediate jump in bitrates so soon after its introduction. For comparison, it took nearly 30 years for 24-bit RGB to be challenged as a display system; consumer DAT recorders were already at 48kHz less than ten years after the introduction of CD.

I take your point about adjustment to high sound levels, but it's not just the absolute dynamic range, it's the non-linearity of that range, and everyone's hearing is different. It's generally accepted that 16-bit PCM divided over 96 dB (okay, 110 with dithering) isn't quite good enough to deal with the peak sensitivity of the ear. 24 bits is definitely a touch of overkill, but it comes out as a nice multiple of bytes, and gives more headroom for mixing and signal processing that is becoming much more common in reproduction equipment.

Dithering the LSB is simply overlaying a 15-bit PCM signal with a PWM signal - you get the downsides of PWM in exchange for a lower noise floor over a part of your frequency range. It isn't adding any information, just hiding the errors in a different place.

I didn't say a correctly upsampled signal would lose information; I said that common methods of upsampling a signal cause information loss, especially from 44.1 to the 48/96/192 rates.

Now the non-technical advantages:

One of the plus points of high bitrate audio is that it has resulted in better quality DACs. Just as CD's higher dynamic range caused an improvement in the quality of amplifiers... that were then used to play vinyl; so the requirement for affordable parts that can handle "24-bit at 192kHz" results in much better reproduction of the 16-bit at 44.1kHz sources we mostly have. Paradoxically, it's only the spread of high-bitrate audio that allowed people to see how marginal its advantage is.

(another non-technical argument is that because 44.1/16 is so wedded to those metal discs that gets played in anything, such recordings have recently been mastered to utter mush just so that they will sound "loud" on cheap equipment; the other formats tend to escape this last step in the process)

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Re: Sound

https://www.hk.onkyo.com/Product/GRANBEAT_DP-CMX1/index.html

You better try this link: https://www.hk.onkyo.com/en/Product/GRANBEAT_DP-CMX1/index.html - may be easier for most people as it's in English :).

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Anonymous Coward

Re: Sound

People arguing over bitrate and DACs, the average punter puts on Girls Aloud or some such other shite while they're texting, ironing, farting or whatever so putting in shit-hot audio tech in a phone is a waste of time and investment.

This.

Although I would have phrased it slightly more eloquent (*cough* :) ), this hits the nail on the head. If you just use a phone as a mobile music player whilst moving around in life the whole discussion is moot anyway. To appreciate the depth and resolution that a proper DAC can offer you need to be set up for it, and at that point you have better kit available anyway.

That's also the small detail that to play back high quality you need high quality input, and I'm not overly impressed with the contents of most online music providers such as iTunes in that respect, also because most of what they supply is compressed to near clipping. An expensive DAC can't undo that.

If I want to really listen to music, it won't be delivered by my phone.

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Re: Sound

You can argue all you like about the quality of the DACs but when the vast majority of people are listening to 128Kbit MP3 through a shit-cheap pair of earbuds - or even worse, the phone's built-in speaker, it really doesn't matter.

What percentage of people who actually care about audio quality actually expect to get it from a phone?

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Re: Sound

" It's chosen to match the capabilities of the human ear - the complete capabilities of the perfect human ear."

Nahh.. It was chosen partly to match our ears capability, but mostly due to the technical limitations at the time. Using such a small margin between sampling frequency and actual Nyquist cut-off frequency introduced a lot of challenges. 16 bit's for the full +/- swing of a signal isn't that spectacular a resolution. Low level signals will be coded with poor resolution.

One question is why CDs are mastered with such awful "hot" (compressed) sound? Is it a result of the characteristics of CD sound? Or is it just engineers that are sh*t compared to the ones that did LP..

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Re: Play back depth is a red herring...

Don't give your kids good headphones. Give them cheap but adequate ones. Better yet, make them buy their own, and they'll learn to not break them...

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Re: Sound

"either way the DAC in the phone is now irrelevant"

Sure, if you are happy to carry around yet another gadget that needs charging, takes up space, and can get stolen or lost (and runs out of power). I think a simple 3.5mm jack with quality IEMs beats that proposition easily for portable everyday audio. And I own a Creative E5, which I use at home mainly.

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Re: Sound @SpeakNoEvil

"For those with a real love of cables"

There's the thin cable coming out of a small 3.5mm connector. And there's the tangle of adapters and different cables... I don't have any love for the latter.

I do like good sound though, so any modern iPhone is off my list. Just one stupid annoyance factor I can do without.

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Re: Sound

Like FatGerman said, most people are listening to streaming audio that's been overcompressed and using cheap earbuds. The DAC simply doesn't matter under such circumstances, and if you could give people a super high end DAC they couldn't tell the difference.

Given that audio output is digital from both Lightning and Bluetooth, if you want a high end DAC by all means buy something that takes Lightning or Bluetooth as input to its high end DAC. There are plenty of such options out there. Even if Apple included a higher end DAC the music snobs would claim it is not good enough and Android phone X includes a better one. If there was a 3.5mm output and nothing else you'd have a legitimate complaint, but as you have digital out quit whining about Apple not including something that a couple percent of people care about.

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Orv
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Re: Sound

For the Millennials I know, 128 kbit went out with Napster and eDonkey. Most stuff now is VBR, and you rarely see anything much under 320 kbit/sec or so (except in MP4, which can do better with lower bitrates.)

Me, I still have a lot of 160 kbit/sec joint stereo stuff. Way back when I had a CD-MP3 player, I auditioned a lot of tracks and decided that was the best compromise, given that I was mostly going to be listening to the stuff in a noisy VW Bus. I've re-ripped some since then, but while my cars have gotten quieter, my hearing has also gotten worse, so it isn't always worth it. ;)

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Orv
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Re: Sound

One question is why CDs are mastered with such awful "hot" (compressed) sound?

Partly it's the "loudness wars." Everything has heavy dynamic range compression now.

Early CD mixes tended to be overly bright. I suspect in some cases they were using masters that already had Dolby NR or RIAA equalization applied, out of laziness.

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Re: Sound

I've obviously mishandled my post and the downvotes are from people that didn't receive it well.

Jokes aside, some people just like to downvote for no good reason.

If they really want a great DAC then they can buy a pair of wireless headphones with a great DAC now or anytime in the future, or buy an android with a great DAC now and plug their crappy headphones in it, their choice I guess.

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Re: Sound

@Orv Re sampling rates. I'll bow to your greater knowledge of millennials, but I do know that Spotify only gives you 320Kbit if you're on a paid Premium subscription, and most of my friends' kids listen to everything on YouTube.

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Anonymous Coward

Re: Sound @SpeakNoEvil

I do like good sound though, so any modern iPhone is off my list. Just one stupid annoyance factor I can do without.

LOL. I fear that doesn't pass the smell test - I deem it unlikely you (or any other human) will be able to tell the difference with your average set of headphones (and even with an above average set).

If you were really able to pick up sound quality you would not even *think* about using a phone for playback (also you don't really want your music enjoyment to be interrupted by the ploink and ping sounds of arriving messages and email - now THERE is a switch I'd like to have available).

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Re: Sound

It seems many people don't understand that the 3.5mm jack was the 'A' in "DAC" (it means "Analog", remember?). Without the jack, there's no point in converting digital signal to analog ones inside the phone anymore.

Don't know about you, but for me, a great feature of my iPhone is being able to have telephone conversations with people

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Re: Sound

I very, very rarely post a link to a video, usually far preferring to read text. However this pair of videos presented by Monty Montgomery of Xiph.org are an excellent exposition of how how digital audio gets converted to sound. One is about 24 minutes long, and the other just over 30 minutes, but really worth the time to watch.

Xiph.org videos: Episode 1: A Digital Media Primer for Geeks; and Episode 2: Digital Show & Tell

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Anonymous Coward

Re: Sound

>How many people do you really think that is going to be useful for?

Come on it's 2017 - just click translate from your context menu if your browser isn't configured to translate automatically. Looks like the site owner or someone has uploaded a manual English version to Google Translate.

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Re: Sound

One question is why CDs are mastered with such awful "hot" (compressed) sound?

It's simply because "it's what the market expects". It's very instructive to look at the oscillogram of "Brothers In Arms" from the 1985 CD and the re-released 2011 version. The later one is compressed and clipped to hell. If the 1985 release had been mastered like that, CD probably wouldn't have taken off as a medium!

Mastering to vinyl is a real skill. I've done it, and I've seen it done properly by a real mastering engineer - there's no comparison! With CD, it's just a case of crank it up to 11 and let the digital clipping take care of the overshoots. The distortion on modern CDs is disgusting and most of them are unlistenable. I'd rather put up with the surface noise, clicks and record wear distortion of vinyl than listen to the modern recorded CD rubbish.

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Re: Play back depth is a red herring...

Couldn't agree more, it's always the bloody wire that goes first but I don't want yet another device that I have to make sure is charged so that alone puts me off wireless.

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Re: Sound

I'm not sure I understand how that argument stands up. Sounds like they're saying "You can plug in better hardware so we're going to give you junk." If they gave us something better as standard, how would that change the ability to plug in something external if the user wanted even better? It sounds like they're kind of showing contempt for their customers in a "You probably couldn't tell the difference anyway so we might as well put more profit in our pockets" way.

A number of years ago, I was given a broken hard drive iPod which I fixed. I never liked the sound of it to the point where I bought a replacement motherboard off eBay because I assumed it must be faulty as I couldn't imagine it being that bad by design. Sadly, the replacement was either identically faulty or they were all that bad. That device's sole purpose was to play music and it had no option for an add-on DAC so what is Apple's excuse for that one?

I can truthfully say I've never heard an Apple device the sound of which I have liked. My Sony MDR-1000x headphones fed over Bluetooth with APT-X kick every one of them I've heard round the room. They don't sound great fresh out of the box on a shop demo but, after about 40 hours of gentle wearing in, they really start to shine. I thoroughly recommend them to you. I'm eagerly waiting for the arrival of Android Oreo which will bring Sony's high-rate lossless LDAC codec to the pairing.

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Re: A load of old pish!

well said Cowherder.

Get this - Bizarrely, I don't use my iPhone for music, and hence dont give a shit about its DAC . Were I to do so i'm sure it would be perfectly adequate - its probably better than the £5 chinese mp3 player / fm transmitter that currently provides music in my car.

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Re: Sound

"generally accepted that 16-bit PCM divided over 96 dB (okay, 110 with dithering) isn't quite good enough to deal with the peak sensitivity of the ear"

*Generally accepted* might be overstretching rather. E.g. see https://people.xiph.org/~xiphmont/demo/neil-young.html - from the bloke who heads up the organisation that invented FLAC, for heaven's sake.

Adoption of hi-res isn't really an argument that it makes a difference to playback (as opposed to mastering, where it is useful). Certain kinds of audiophile will buy all sorts of silly things, up to and including bags of pebbles to place into the corners of their rooms (http://www.machinadynamica.com/machina31.htm).

Of course, this doesn't mean Apple shouldn't supply a hi-res DAC. It costs incredibly little, all the decent DACs have it anyway, and it will make some people feel better.

What would be great is a better quality DAC and a decent headphone amp, would probably make an appreciable difference. Having to pay significant amounts extra for an external DAC and all the inconvenience that entails to get that does seem a bit rubbish for a premium device.

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Re: Sound

@Paul Stimpson

"Sounds like they're saying "You can plug in better hardware so we're going to give you junk.""

they don't give you anything beyond the DAC that powers the built in speakers as there is no 3.5mm jack. the lightening to 3.5mm jack has its own DAC in the cable. Streaming sound to anything will use the DAC in the playback hardware. The money saved has gone into improving something else like the camera or screen, or cpu.

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Re: Sound

>>and demonstrates confusion over things like nyquist frequency, and the accuracy of phase information in a sampled signal...

>I can't see how you came to that conclusion

For one you complained that at the nyquist frequency you can lose signal - which is never in question.

For another with a band limited signal there is no loss of phase information from sampling.

Monty goes over this with a square wave (including explaining about the effects of a low pass filter on a square wave), demonstrating the perfect replication of the signal, and the absolute reproduction of all phase information.

44.1k/16 bit is (more than) sufficient for the human ear. If you would like to come and take a double blind test against some super-dooper MHz sampling with MB depth then you are welcome to - I'll set one up with some of my hardware, and some of yours.

One of the main differences that people tend to hear is, as you rightly point out, the quality of the master being different for the two formats. But if you take a HiDef master and play that, as well as playing it through a ADAC at 44k/16 then you won't hear a difference (you'll need to apply a slight delay to the master signal in order to allow the A/B testing to not 'give the game away').

The quality of the DAC and the master have nothing to do with the limits of 44.1k/16 bit sampling - those limits are outside of the relevant ranges for humans.

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Re: Sound

The money saved has gone into improving something else like the camera or screen, or cpu

Given that the DAC should be on the SOC processor, and the IP cost of different grades of DAC on an SOC would be minimal, how much extra quality will they get, spending an extra ten cents on the camera and screen?

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Re: Sound

The DAC isn't on the SoC - then the SoC would have analog pins, ugh! The DAC is separate in all iPhones (I'll bet all smartphones) just look at the teardowns. The iPhone 7 has one for each speaker, located very near it.

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@John Robson- Re: Sound

" one you complained that at the nyquist frequency you can lose signal - which is never in question

For another with a band limited signal there is no loss of phase information from sampling."

But both of those "complaints" are real things.

Okay, the Nyquist frequency is the maximum frequency component that can be reproduced by a sampling system. Obviously this will be 0.5fs, because two samples are required to capture the positive and negative cycles of a sinewave. Anything above that frequency can't be adequately captured. That's Nyquist's Theorem (and Shannon's)

But, and this is the bit I think you've missed, this assumes that the sampling clock and signal component at 0.5fs are phase-coherent. Nyquist describes the theoretical maximum information capture, which requires an assumption about phase.

Consider a signal with only a single sinewave component at exactly 0.5fs of amplitude ±1.0, sampled at fs. If the sampling clock and the signal are in the appropriate phase, the samples will be obtained at the peak and trough of that waveform, resulting in a train of +1.0, -1.0, +1.0, -1.0. Perfectly captured, perfectly reproducible. That's the situation Nyquist described.

But: shift the phase of that signal by 90 degrees. Now the sampling occurs at the zero crossing points, and the output is a train of 0, 0, 0, 0, 0, ... How is that distinguishable from silence? But there was a component at the Nyquist frequency in the input. The thing is that Nyquist's theorem assumes that the phase of the components are compatible with the sampling clock.

90 degrees is the worst case, but at other phase offsets, you lose amplitude accuracy. If you were to shift that input signal to be 45 degrees out of phase with the sampling signal, the signal will be present, but as +0.7071, -0.7071, +0.7071... right frequency, wrong amplitude.

As you shift the phase of an input signal that's close to fs, the recorded amplitude will appear to change - this is loss of information (The amount of error depends on how close your component is to the Nyquist frequency) That is not a controversial or "wrong" position, it's a fundamental property of sampling, and it's the main reason why signals with a 20kHz bandwidth are sampled at 96k and 192k.

I do agree with your other points: final mastering has done a lot to ruin the reputation of CDDA (although lousy DACs that weren't linear to 16-bits did their damage before then), and yes, the differences are marginal at the end. I don't think that the higher rates are very useful in themselves, but rather in the way they give adaptive reproduction equipment more "real" information to work with, so that when they've finished mangling and munging the samples, what's left is still as good as 44.1/16.

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Re: Sound

"What percentage of people who actually care about audio quality actually expect to get it from a phone?"

The early ones were actually very good. As good as the dedicated iPods.

Today's aren't so good, as they don't play any music at all. You need some other hardware for that now.

I haven't tried the BT small things that Apple sell (no doubt for quite a lot), but I bet Mr Jobs would have sorted things out before it got so out of hand. There are smaller physical plugs than 3.5mm, for a start.

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Re: Sound

Don't assume your average ears are compulsory. I have been tested up to 28khz sound -- i.e. 56khz sampling. (CDs sample at 44khz to allow 22khz sound, but the algorithm decays badly at its top end and effectively cuts off around 20khz. Which is why most retail speakers cut off at 20khz.) Blind testing by wotsisname, the tech guru, at What HiFi(?) 15 years ago found that even average ears could distinguish between music incorporating high-30s sound vs CDs, despite not being able to detect those tones in isolation.

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Re: Sound

I think we just know different kids. The ones I know make music as well as listening to it, which probably ups their quality expectations.

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Orv
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Re: Sound

Of course, this doesn't mean Apple shouldn't supply a hi-res DAC. It costs incredibly little, all the decent DACs have it anyway, and it will make some people feel better.

The thing is, the people who would feel better would be audiophiles, who are never going to trust an on-board DAC anyway. They'll want something with special capacitors and silver wire-wound resistors and charged only with electrons that have passed through a mechanically-tuned power cord.

Putting together their own expensive placebo effect is most of the fun for these people. Don't take that away from them.

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