What more do we want?

As I sit here listening to some big symphonic music playing on my ‘KEF’ DSP-based active crossover stereo system, I am struck by the thought: how could it be any better?

I sometimes read columns where people wonder about the future of audio, as though continuous progress is natural and inevitable – and as though we are accustomed to such progress. But it does occur to me that there is no reason why we cannot have reached the point of practical perfection already.

I think the desire for exotic improvements over what we have now has to be seen within the context of most people having not yet heard a good stereo system. They imagine that if the system they heard was expensive, it must therefore represent the state of the art, but in audio I think they could well be wrong. Some time ago, the audio industry and enthusiasts may even have subconsciously sniffed that they were reaching a plateau and begun to stall or reverse progress just to make life more interesting for themselves.

At the science fiction level, people dream of systems that reproduce live events exactly, including the acoustics of the performance venue. Even if this were possible, would it be worth it without the corresponding visuals? (and smells, temperature, humidity, etc.?)

Something like it could probably be achieved using the techniques of the computer games industry: synthesis of the acoustics from first principles, headphones with head tracking, or maybe even some system of printed transducer array wall coverings that could create the necessary sound fields in mid-air if there was no furniture in the room (and knowing the audio industry, it would also supplement the system with some conventional subwoofers). My prediction is that you would try it a couple of times, find it a rather contrived, unnatural experience, and next time revert to your stereo system with two speakers.

On a more practical level, the increasing use of conventional DSP is predicted. We are now seeing the introduction of systems that aim to reduce the (supposedly) unwanted stereo crosstalk that occurs from stereo speakers. The idea is to send out a slightly attenuated antiphase impulse from one speaker for every impulse from the other speaker, that will cancel out the crosstalk at the ‘wrong ear’. It then needs to send out an anti-antiphase impulse from the other speaker to cancel out that impulse as it reaches the other ear, and so on. My gut instinct is that this will only work perfectly at one precise location, and at all other locations there will be ‘residue’ possibly worse than the crosstalk. In fact we don’t seem bothered by the crosstalk from ordinary stereo – I am not convinced we hear it as “colouration”. Maybe it results in a narrowing of the width of the ‘scene’, but with the benefit of increasing its stability. (Hand-waving justification of the status quo, maybe, but I have tried ambiophonic demonstrations, and I was eventually happy to go back to ordinary stereo).

Other predictions include the increasing use of automatic room correction, ultra-sophisticated tone controls and loudness profiles that allow the user to tailor every recording to their own preferences.

Tiny speakers will generate huge SPLs flat down to 20 Hz – the Devialet Phantom is the first example of this, along with the not-so-futuristic drawback of needing to burn huge amounts of energy to do it. Complete multi-channel surround envelopment will come from hidden speakers.

At the hardware fetish end, no doubt some people imagine that even higher resolution sample rates and bit depths must result in better audible quality. Some people probably think that miniaturised valves will transform the listening experience. High resolution vinyl is on the horizon. Who knows what metallurgical miracles await in the science of audio interconnects?

For the IT-oriented audiophile, what is left to do? Multi-room audio, streaming from the cloud, complete control from handheld devices are all here, to a level of sophistication and ease of use limited only by the ‘cognitive gap’ between computer people and normal human users that sometimes results in clunky user interfaces. The technology is not a limiting factor. Do you want the album artwork to dissolve as one track fades out and the new artwork to spiral in and a CGI gatefold sleeve to open as the new track fades in? The ability to talk to your device and search on artist, genre, label, composer, producer, key signature? Swipe with hand gestures like Minority Report? Trivial. There really is no limit to this sort of thing already.

In fact, for the real music lover, I don’t think there is anything left to do. Truth be told, we were most of the way there in 1968.

The basic test is: how much better do you want the experience of summoning invisible musicians to your living room to be? I can’t imagine many worthwhile improvements over what we have now. The sound achievable from a current neutral stereo system is already at ‘hologram’ level; the solidity of the phantom image is total – the speakers disappear. It isn’t a literal hologram that reproduces the acoustics in absolute terms, allowing you to walk around it, of course, but it is a plausible ‘hologram’ from any static listening position, allowing you to ‘walk around it’ in your mind, and it stays plausible as you turn your head.

It isn’t complete surround envelopment, but there is reverberation from your own room all around you, and it seems natural to sit down and face the music. You will hear fully-formed, discrete, musical parts emerging from an open, three dimensional space, with acoustics that may not be related to the space you are listening in. You have been transported to a different venue – if that is what the recording contains. In terms of volume and dynamics, a modern system can give you the same visceral dynamics as the real performance.

And all this is happening in your living room, but without any visuals of the performance – it is music that you are wanting to listen to after all. If the requirement is to experience a literal night at the opera, then short of a synthesised Star Trek type ‘holodeck’ experience you will be out of luck.

You could always watch a high resolution DVD of some performance or the BBC’s Proms programmes, for example, and such visuals may give you a different experience. They will, however, destroy the pure recreation of the acoustic space in front of you because, by necessity, the visuals jump around from location to location, scene to scene in order to maintain the interest level, and your attention will be split between the sound and the imagery. Anyway, a huge TV will cost you about £200 from Tescos these days so that aspect is pretty well covered, too.

The natural partner to a huge TV is multi-channel surround sound. Quadraphonic sound seemed like the next big thing in the 1970s, but didn’t take off at the time. We now have five or seven channel surround sound. Does this improve the musical experience? Some people say so, but that could just be the gimmick factor, or an inferior stereo system being jazzed up a bit. While the correlation between two good speakers produces an unambiguous ‘solution’ to the equations thereof, multiple sources referring to the same ‘impulse’ could result in no clear ‘solution’ – that is, a fuzzy and indistinct ‘hologram’ that our ears struggle to make sense of. Mr. Linkwitz surmises something similar in the case of the centre speaker, plus he finds it visually distracting; with just two speakers, the space between them becomes a virtual blank space in which it is easier to imagine the audio scene. Most recordings are stereo and are likely to remain that way with a large proportion of listeners using headphones. For these reasons, I am happy that stereo is the best way to carry on listening to music.

Can DSP improve the listening experience further? Hardly at all I would say. So-called ‘room correction’ cannot transform a terrible room into a great one, and it doesn’t even transform a so-so one into a slightly better one. It starts from a faulty assumption: that human hearing is just a frequency response analyser for which real acoustics (the room) are an error, rather than human hearing having a powerful acoustics interpreter at the front end. If you attempt to ‘fix’ the acoustics by changing the source you just end up with a strange-sounding source. At a pinch, the listener could listen in the near(er) field to get rid of the room, anyway.

I am convinced that the audiophile obsession with tailoring recordings to the listener’s exact requirements is a red herring: the listener doesn’t want total predictability, and a top notch system shouldn’t be messed about with. As a reviewer of the Kii Three said:

…the traditional kind of subjective analysis we speaker reviewers default to — describing the tonal balance and making a judgement about the competence of a monitor’s basic frequency response — is somehow rendered a little pointless with the Kii Three. It sounds so transparent and creates such fundamentally believable audio that thoughts of ‘dull’ or ‘bright’ seem somehow superfluous.

The user doesn’t have access to the individual elements of the recording. What can be done in terms of, say, reducing the volume of the hi-hats (or whatever) is crude and unnatural and bleeds over every other element of the recording. The only chance of reproducing a natural sound, maintaining the separation between fully-formed elements and reproducing a three dimensional ‘scene’, is for the system to be neutral. When this happens, the level of the hi-hats likely just becomes just part of the performance. Audiophiles who, without any caveat, say they want DSP tone controls in order to fiddle about with recordings have already given up on that natural sound.

In summary, I see the way music was ‘consumed’ 40 or even 50 years ago as already pretty much at the pinnacle: two large speakers at one side or end of a comfortably-furnished living room, filling the space with beautiful sound – at once combining compatibility with domestic living and the ability to summon musicians to perform in the space in a comprehensible form that one or several people can enjoy without having to don special apparatus or sit in a super-critical location. And the fitted carpets of those times were great for the acoustics!

All that has happened in the meantime is just the ‘mopping up’ of the remaining niggles. We (can) now have better performance with respect to distortion, frequency response, dynamic range, and a more solid, holographic audio ‘scene’; no scratches and pops; instant selection of our choice of the world’s total music library. The incentives for the music lover to want anything more than this are surely extremely limited.

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Beolab 50, Home HiFi Show 2017

For the first time in a while I have been to a hi fi show, this time in Harrogate, North Yorkshire. It was arranged by the forum HiFi Wigwam, and there were both commercial and amateur exhibitors. It was fairly low key: not all that many exhibitors and not too many visitors on the day I was there (Saturday). I liked the venue, The Old Swan Hotel.

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My main reason for going was to hear the Bang and Olufsen Beolab 90s, but those weren’t there. Instead the Beolab 50s were being demonstrated in a very large room as shown above. There was a technical problem: they couldn’t change the settings for the speakers because of wi fi issues – it can only be done from a phone app (I think) and it needs to find the speakers on the network. So they were stuck on a fairly omni-directional setting and I could really hear this: I desperately needed them to be more focused. But anyway, very generously, the sales guy allowed me to play tracks off a memory stick I had brought, and gave me control of the volume.

My impression was of a beautifully clean, effortless sound, and incredible bass, but the setup was just ‘not right’ and everything sounded too diffuse and distant. Nevertheless, I enjoyed playing some good demo tracks and it was easy to hear that these speakers are not troubled by high volume levels – although I didn’t get anywhere near the volume they normally run demos at!

I must try to get a demo when they are set up properly – I expect great things from them. (I feel a bit of a fraud though, because at over £20,000 I won’t be buying them!).

My friend was very impressed by the looks of these speakers: solid-looking aluminium, fine wooden grilles, and a tweeter ‘pod’ that disappears when the speakers are inactive. In fact, he was very taken by the whole B&O ‘ethos’. Even the remote control for the system was a work of art, being made from a single piece of aluminium. And B&O do the best brochures of any hi-fi company, I think!

In the rest of the show, we heard some enormous horn speakers – I am not a fan, KEF LS50 wireless, some BBC-style LS5/9, some early Harbeths, some Focal speakers, some tiny actives based on balanced mode radiators, and quite a few others. There were various vintage components from the 1970s onwards. My friend was quite taken with the sound of some very classic-looking Tannoys with concentric tweeters, and anything that sounded good on a lower budget – I don’t have the brochure to hand, but may fill in some more details later.

Valves were on show of course, a few turntables, some outrageously inefficient Class A solid state amplifiers, and some active crossovers. In some setups, vinyl sounded OK, but because of the pops and clicks I often found myself wishing for digital sources!

There were the usual vinyl stalls, cables and accessories at eye watering prices, an interesting exhibition of photos of pop stars from the 60s and a great jukebox.

Acoustics-wise, the standard rooms were quite good, I thought, having higher ceilings than some other places.

Artisanal Audio

Just enjoying reading an article about Artisanal Audiophilia – a phrase that makes you look twice, I think – by Richard Varey (who was kind enough to link to one of my posts on his web site). I am looking forward to reading many more of his articles.

…artisan audio is handbuilt, usually by the designer, and is not mass-produced but made in small batches, made-to-order as a customised one-off, or is customisable and upgradable. They carry the name of the creator as the brand. They combine boutique audio engineering with design creativity driven by functionality and craftsmanship. They are made for audiophiles, promising authenticity, so not for the hipster or fashion conscious, nor the casual listener.

I was going to leave a comment, but it turned out a bit too long!

I take a sceptical view about boutique audio in general. I think that the crucial factors are:
1. It’s very hard to make audio equipment that doesn’t work to some extent.
2. Music is an exquisite, possibly expensive art form created by very talented, skilled people, and at the same time something that we hear spontaneously when birds sing or someone drums their fingers.
3. While other ‘artisan’ products (pens, watches, etc.) have to create their own ‘art’, audio equipment merely passes through someone else’s art.

Put these things together, and it becomes easy to equate a beautiful hand made passive volume control (or whatever) with art, craftsmanship, skill, etc. But my view (please challenge me on this) is that the reality is that its sound is all in the user’s mind. Of course, this is not in itself a bad thing – the perceived sound is real at the only level that really matters. However, it may be cheaper for the listener to train themselves to go into that state of mind when listening to a standard volume control!

What many people may not understand is that it would be very difficult to make a piece of wire or some other electrical conductor do anything at all to the signal except pass it unchanged. Creating an audiophile passive volume control or connecting cable is not like creating a fountain pen or a watch – even if the creator of it borrows the same aesthetic. All audio equipment, particularly the passive variety, *will* ‘work’ – you cannot stop it from doing so even if you try quite hard!

The Logic of Listening Tests

Casual readers may not believe this, but in the world of audiophilia there are people who enjoy organising scientific listening tests – or more aptly ‘trials’. These involve assembling panels of human ‘subjects’ to listen to snippets of music played through different setups in double blind tests, pressing buttons or filling in forms to indicate audible differences and preferences. The motivation is often to use science to debunk the ideas of a rival group, who may be known as ‘subjectivists’ or ‘objectivists’, or to confirm the ideas of one’s own group.

There are many, many inherent reasons why such listening tests may not be valid e.g.

  • no one can demonstrate that the knowledge you are taking part in an experiment doesn’t impede your ability to hear differences
  • a participant who has his own agenda may choose to ‘lie’ in order to pretend he is not hearing differences when he, in fact, is.
  • etc. etc.

The tests are difficult and tedious for the participants, and no one who holds the opposing viewpoint will be convinced by the results. At a logical level, they are dubious. So why bother to do the tests? I think it is an ‘appeal to a higher authority’ to arbitrate an argument that cannot be solved any other way. ‘Science’ is that higher authority.

But let’s look at just the logic.

We are told that there are two basic types of listening test:

  1. Determining or identifying audible difference
  2. Determining ‘preference’

Presumably the idea is that (1) suggests whether two or more devices or processes are equivalent, or whether their insertion into the audio chain is audibly transparent. If a difference is identified, then (2) can make the information useful and tell us which permutation sounds best to a human. Perhaps there is a notion that in the best case scenario a £100 DAC is found to sound identical to a £100,000 DAC, or that if they do sound different, the £100 DAC is preferred by listeners. Or vice versa.

But would anything actually have been gained by a listening test over simple measurements? A DAC has a very specific, well-defined job to do – we are not talking about observing the natural world and trying to work out what is going on. With today’s technology, it is trivial to make a DAC that is accurate to very close objective tolerances for £100 – it is not necessary to listen to it to know whether it works.

For two DACs to actually sound different, they must be measurably quite far apart. At least one of them is not even close to being a DAC: it is, in fact, an effects box of some kind. And such are the fundamental uncertainties in all experiments involving the asking of humans how they feel, it is entirely possible that in a preference-based listening test, the listeners are found to prefer the sound of the effects box.

Or not. It depends on myriad unstable factors. An effects box that adds some harmonic distortion may make certain recordings sound ‘louder’ or ‘more exciting’ thus eliciting a preference for it today – with those specific recordings. But the experiment cannot show that the listeners wouldn’t be bored with the effect three hours, days or months down the line. Or that they wouldn’t hate it if it happened to be raining. Or if the walls were painted yellow, not blue. You get the idea: it is nothing but aesthetic judgement, the classic condition where science becomes pseudoscience no matter how ‘scientific’ the methodology.

The results may be fed into statistical formulae and the handle cranked, allowing the experimenter to declare “statistical significance”, but this is just the usual misunderstanding of statistics, which are only valid under very specific mathematical conditions. If your experiment is built on invalid assumptions, the statistics mean nothing.

If we think it is acceptable for a ‘DAC’ to impose its own “effects” on the sound, where do we stop? Home theatre amps often have buttons labelled ‘Super Stereo’ or ‘Concert Hall’. Before we go declaring that the £100,000 DAC’s ‘effect’ is worth the money, shouldn’t we also verify that our experiment doesn’t show that ‘Super Stereo’ is even better? Or that a £10 DAC off Amazon isn’t even better than that? This is the open-ended illogicality of preference-based listening tests.

If the device is supposed to be a “DAC”, it can do no more than meet the objective definition of a DAC to a tolerably close degree. How do we know what “tolerably close” is? Well, if we were to simulate the known, objective, measured error, and amplify it by a factor of a hundred, and still fail to be able to hear it at normal listening levels in a quiet room, I think we would have our answer. This is the one listening test that I think would be useful.

The Trouble with Hobbies

Have you ever suddenly been inspired to embark on a brand new hobby?

Maybe you’ve never owned a boat before, but having seen one chug by on the river you have thought “I’d love to do that!”. A quick browse in the classified ads shows lots of boats that look fine, and they don’t cost all that much. Basically any boat would be great, and you could gradually do it up, even if it is a bit shabby now. In your mind’s eye, your family will love you when you are able to take them on spur-of-the-moment, cheap weekends messing about on the water, starting in a few weeks’ time.

From this high point where the world is your oyster, you begin to take the advice of the magazines and other experienced hobbyists. Before you have even owned a boat, you become aware of the hierarchy of boat owners, and the boats that would render you a laughing stock if you owned them. You become aware of the general consensus on different types of bilge pump – not something you ever wanted to know. You begin to form an idea of the boat you should really go for – and it is not one of the bargain basement jobs you first saw. You might just about be able to stretch to a boat that would put you in the lower echelons of boat ownership but, importantly, not on the very lowest rung. You could always, perhaps, move up from there over time.

It now turns into an all-consuming hobby with the goal of having a boat on the river at the end of the year. In the end it costs thousands, and your children have grown up and left home before your boat finally takes to the water. You hit a bridge and rip the top off your boat the first time you take it out. You feel sick and abandon the whole hobby (a true story).

That’s the nature of male hobbies. They start out as wonderful, spontaneous ideas, but can turn into nightmares – mainly due to the existence of other hobbyists! Audio is one of those hobbies, I think. Ridiculously, the prices paid for bits of audio knickknackery rival the costs of boats.

A person could be seized one day by the idea of hi-fi as a way to improve their life, buy an amp and some secondhand speakers off Gumtree for £100, and plug their tablet or laptop headphone socket into the amp using a £2 cable. Hey presto, a hi-fi system that will sound much better than what they had before, and which has tinker-ability via the buying and selling of speakers and the audio streaming/library software options; there is no urgency in changing the amp and tablet hardware as they are pretty much perfect in what they do. The speakers are almost like pieces of furniture, so the person can indulge their tastes in how they look as well as how they sound, and they can be restored using standard DIY skills – a nice mini-hobby.

But what if the person does the natural male thing, and starts to read the magazines and forums? Immediately they will realise that their tablet’s headphone output is a joke in the audio world. They need to spend at least a few hundred pounds on a half-decent ‘DAC’, plus a couple of hundred on a budget cable. And of course, this is only for convenience: real audio quality can only be had if they own a decent turntable and a special vibration-free shelf to put it on. Where do they go from there? They need to make a decision on which turntable and which cartridge to go for. They need to take a view on cables, power conditioners, valve or solid state amps, accessories like cable lifters and record cleaning machines. Each decision, they are assured by their fellow hobbyists, will result in “night and day” differences in the sound.

After some months agonising over it, they assemble a beginner’s system for about £3,000 – they will upgrade as budget allows. It sounds OK, but they know that even though the brand is a highly recommended one, the particular model of valve amplifier they could afford has “hints of a slightly reticent mid range” – one of the magazines said so – and if they listen carefully, perhaps they can hear that… But the more powerful 18 Watt model cost £800 more and they decided against it. Perhaps they made the wrong decision. The nightmare unfolds…

Thoughts on creating stuff

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The mysterious driver at the bottom is the original tweeter left in place to avoid having to plug the hole

I just spent an enjoyable evening tuning my converted KEF Concord III speakers. Faced with three drivers in a box, I was able to do the following:

  • Make impulse response measurements of the drivers – near and far field as appropriate to the size and frequency ranges of the drivers (although it’s not a great room for making the far field measurements in)
  • Apply linear phase crossovers at 500Hz/3100Hz with a 4th order slope. Much scope for changing these later.
  • Correct the drivers’ phase based on the measurements.
  • Apply baffle step compensation using a formula based on baffle width.
  • Trim the gain of each driver.
  • Adjust delays by ear to get the ‘fullest’ pink noise sound over several positions around the listening position.
  • ‘Overwrite’ the woofer’s natural response to obtain a new corner frequency at 40 Hz with 12dB per octave roll off.

The KEFs are now sounding beautiful although I didn’t do any room measurements as such – maybe later. Instead, I have been using more of a ‘feedforward’ technique i.e. trust the polypropylene drivers to behave over the narrow frequency ranges we’re using, and don’t mess about with them too much.

The benefits of good imaging

There is lovely deep bass, and the imaging is spectacular – even better than my bigger system. There really is no way to tell that a voice from the middle of the ‘soundstage’ is coming from anywhere but straight ahead and not from the two speakers at the sides. As a result, not only are the individual acoustic sources well separated, but the acoustic surroundings are also reproduced better. These aspects, I think, may be responsible for more than just the enjoyment of hearing voices and instruments coming from different places: I think that imaging, when done well, may trump other aspects of the system. Poorly implemented stereo is probably more confusing to the ear/brain than mono, leaving the listener in no doubt that they are listening to an artificial system. With good stereo, it becomes possible to simply listen to music without thinking about anything else.

Build a four way?

In conjunction with the standard expectation bias warning, I would say the overall sound of the KEFs (so far) is subtly different from my big system and I suspect the baffle widths will have something to do with this – as well as the obvious fact that the 8 inch woofers have got half the area of 12 inch drivers, and the enclosures are one third the volume.

A truly terrible thought is taking shape, however: what would it sound like if I combined these speakers with the 12 inch woofers and enclosures from my large system, to make a huge four way system..? No, I must put the thought out of my head…

The passive alternative

How could all this be done with passive crossovers? How many iterations of the settings did it take me to get to here? Fifty maybe? Surely it would be impossible to do anything like this with soldering irons and bits of wire and passive components. I suppose some people would say that with a comprehensive set of measurements, it would be possible to push a button on a computer and get it to calculate the optimum configuration of resistors, capacitors and inductors to match the target response. Possibly, but (a) it can never work as well as an active system (literally, it can’t – no point in pretending that the two systems are equivalent), and (b) you have to know what your target response is in the first place. It must surely always be a bit of an art, with multiple iterations needed to home in on a really good ‘envelope’ of settings – I am not saying that there is some unique golden combination that is best in every way.

In developing a passive system, every iteration would take between minutes and hours to complete and I don’t think you would get anywhere near the accuracy of matching of responses between adjacent drivers and so on. I wouldn’t even attempt such a thing without first building a computerised box of relays and passive components that could automatically implement the crossover from a SPICE model or whatever output my software produced – it would be quite big box, I think. (A new product idea?)

Something real

With these KEFs, I feel that I have achieved something real which, I think, contrasts strongly with the preoccupations of many technically-oriented audio enthusiasts. In forums I see threads lasting tens or even hundreds of pages concerning the efficacy of USB “re-clockers” or similar. Theory says they don’t do anything; measurements show they don’t do anything (or even make things worse with added ground noise); enthusiasts claim they make a night and day improvement to the sound -> let’s have a listening test; it shows there is no improvement; there must have been something wrong with the test -> let’s do it again.

Or investigations of which lossless file format sounds best. Or which type of ethernet cable is the most musical.

Then there’s MQA and the idea that we must use higher sample rates and ‘de-blurring’ because timing is critical. Then the result is played through passive speakers with massive timing errors between the drivers.

All of these people have far more expertise than me in everything to do with audio, yet they spend their precious time on stuff that produces, literally, nothing.

The Subjectivist/Objectivist Synthesis (Audiostream’s latest article)

Audiostream has posted a new article on the Objectivist/”Subjectivist” debate.

(I have to be careful to put inverted commas around the word “subjectivist” because, as an earlier commenter pointed out quite rightly, “subjectivists” rarely justify their name; in reality they are usually claiming that their subjective experiences are a superior form of objective measurement).

In summary, the new article says “Hey, everyone’s views are valid. Let’s not too get dogmatic, and just have a beer”. I think this misses the point (or several points). For me, the biggest ones are these:

  • Measurements are always incomplete, and are just part of the picture; this seems to be misunderstood by many people, who think that there is a supernatural mystery as to why supposedly good measurements don’t always correlate with good sound. I don’t think there is a mystery.
  • Subjective experiences are always affected by spurious factors; if the measurements of what comes out of the speakers show substantial deviation from the signal (i.e. are ‘bad’), this, for me, trumps the subjective opinion. But as mentioned above, if the measurements are ‘good’ they may still be incomplete.
  • Let’s only start worrying about the above when we’ve designed the system to avoid the obvious errors as best we can. This is neither objectivism, nor “subjectivism”, but rationalism. For reasons of tradition and ‘folk intuition’, this may be rare in the world of hi-fi.
  • I would be only too keen to hear people’s subjective experiences if they are referring to something measurably out of the ordinary and arguably good; less so if they are describing differences between digital cables that, rationally, cannot be affecting the sound. Some people do it all within the same article!

More digital cable fun

Audiostream has another digital cable promotional article.

Within it is a little aside of a type that I often see:

<some company> is choosing to keep mum on the specifics relating to how these cable’s differing materials and construction impart different sonic flavors.

In fact no one has ever revealed the secret of how an ethernet cable (or any cable for that matter) imparts different sonic flavours – for the simple reason that it is impossible. We know it is impossible because this is a man-made, engineered system, one of whose primary purposes is to make it impossible. If, in fact, an ethernet cable physically changes the sound (as opposed to placebo effects), then this is not a digital audio system at all. It would probably be best to repair it, re-design it, or throw it away sell it to the nearest person who believes that manufacturers of audio cables “keep mum” only because they have valuable secrets to safeguard.

Digital cables: a lack of understanding

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There’s a new article about digital cables which is directly relevant to my post a couple of weeks back – it even features the “eye diagram” I referred to.

It purports to ‘debunk’ the idea that “bits are bits”, but in reality it does nothing of the sort. It starts off with a question that it fails to answer and doesn’t come back to again:

Asynchronous USB audio to the rescue?

The remainder of the article is about isochronous USB and seeks to suggest that it is not just about getting all the data through intact, but that there are issues with timing, jitter and noise. Judging by the comments that follow, the readership is entirely unaware that it is a non sequitur they have been reading.

There is a strange little “Note” placed halfway down in tiny lettering that says

Do not confuse ‘asynchronous USB’ with ‘Isochronous,’ an asynchronous USB system still uses Isochronous mode to transfer audio.

I am not quite sure what that is supposed to mean, but again it seems to be an appeal to the false idea that it is beyond the wit of man to deliver digital audio data without it being corrupted, or affected by timing. As I have said before, if this were true, then systems such as TIDAL could not work: the data has come through thousands of miles of cheap cable not even made of silver or raised from the floor on little ceramic pots, through hundreds of utilitarian digital switches, and eventually into your home via the cheapest connector that your telecoms company could provide. And yet it works perfectly; all the electrical noise of the world’s internet, and all the jitter that comes from being re-routed dynamically hundreds of times every second, is completely absent.

As I said in my earlier post, we need to understand the system at a higher level. Asynchronous USB and other on-demand packet-based systems are immune to cable quality once it is beyond some minimum standard, and electrical isolation removes the possibility of noise being injected into your audio system – even enabling you to listen to music off the WWW without all the electrical noise of the global internet spoiling your listening pleasure. Really, getting data from a file/CD/stream into your DAC and reading it out at a precise rate is a simple engineering problem, rendered trivial and cheap for the consumer by some very clever people who actually understand the problem, and have solved it.

Understanding vs. Knowledge vs. Expertise

Reading Archimago’s latest article, I am struck by two things:

(a) he’s probably a much nicer person than me

(b) the high end audio business may not be so much a scam as a <word that begins with “cluster”>.

What I’m thinking is that millions of words (not Archimago’s I hasten to add) and thousands of product developments can all stem from an incomplete understanding of something, plus the obscuring of central ideas with mere facts and ‘expertise’. Case in point is the subject of digital cables, discussed in the article. Archimago has endless patience and ‘plays along’ with the manufacturers and their disciples, giving them the benefit of the doubt by testing their products, even though he knows that they will always give more-or-less identical results. I am more inclined towards the idea that we should just ignore them. Unfortunately, neither approach can rid us of the cloud of confusion that surrounds the subject, and which must ultimately divert attention away from real progress (and with the Kii Three and Beolab 90, for example, we at last have some real progress to evaluate, and hopefully to make cheaper).

Which of the the following propositions are false?

1. Digital audio is degraded by jitter.

2. Cables carrying digital audio signals impart jitter onto those signals.

3. High quality cables can be designed to reduce jitter compared to others.

4. Digital audio can be improved by high quality cables.

I would say that none of them is completely false in all circumstances, and herein lies the problem. An entire industry is sustained on these propositions; manufacturers talk knowledgeably (and who knows, maybe honestly) about them. But while the propositions may all be true individually and with qualifications, they are an incomplete representation of the role of cables in digital audio. An understanding of digital audio at a system level would show that many implementations are certain to be immune to cable quality (and the remainder of implementations are highly insensitive to it). Those bi-directional implementations that deliver the audio data in packets on demand, slaved to the DAC’s sample rate, are immune to cable-induced jitter by design. Case closed. We could simply move on.

But if you have the misfortune to enter into a discussion about the subject on a forum, you will quickly encounter many vociferous people with detailed factual knowledge and expertise regarding cables, and that that is all they want to talk about; it won’t be long before someone brings up “eye patterns”, transmission line theory, the “skin effect”, “six nines” copper, monocrystalline metal and so on. Or they want to talk about listening tests and statistical ‘p-values’. This lower level knowledge, even if correct within its own little sub-fields, is not really relevant, but unfortunately forms a smokescreen that obscures all understanding.