KEF at the cutting edge


There’s a very interesting and comprehensive paper by KEF on the design of their Reference Series speakers. It shows, I suppose, that there is a huge difference between ’boutique’ manufacturers and a world class company that can pour huge resources into optimising every aspect of a design. I can’t say I have heard these speakers, but I would be expecting something pretty impressive.

I like the idea of the ‘tangerine waveguide’ which seems to be an object whose shape was possibly ‘evolved’ in a computer using finite element analysis (FEA). This could be an example of the power of ‘dumb’ software alone to trump all human expertise. By that I mean that once a computer can be programmed to simulate a physical system effectively from first principles, it can be given the task of finding an optimal solution to a particular problem – if such a solution can be found at all. The process can be speeded up using human intuition to define the starting conditions perhaps, but the computer would eventually find the answer anyway.

In this case, the human input might involve the desire to modify the tweeter’s dispersion so that it blends perfectly with the surrounding mid-range driver, with an expectation that a small object placed in front of the tweeter might do it, but with no idea of what the shape of that object might be (that would be my situation anyway!). I imagine that a virtual model of the tweeter dome and mid-range driver cone could be provided, along with some constraints on the shape of the waveguide – it has to be manufacturable – and that the computer could start simulating the system’s performance in terms of on- and off-axis frequency response, slowly homing in on better and better solutions using genetic algorithms, perhaps. The waveguide takes shape as a complex 3D object that in the good old days of audiophile yore it might not have been possible to make, but can now be manufactured using CAM machines. At no point in this process would a human even need to understand the mathematics of the shape, but they could verify that the solution is robust by checking the virtual performance with extremes of manufacturing tolerances, surface finishes and so on. The presence of the waveguide will influence the design of the crossover, and again the computer could be programmed to come up with the optimal solution for that, also.

It is a heady brew, I think: the person who can program a computer to simulate systems from first principles has at his fingertips the power to exceed all previous human design expertise. This expertise was, in reality, just rules of thumb and short cuts, and engineers of all kinds have always engaged routinely in trial-and-error optimisation of systems; they may ‘understand’ the mathematics behind the system they are designing, but ultimately they optimise using trial-and-error anyway.

There were a couple of sections within the KEF paper that I looked forward to reading, anticipating that the engineers might have some difficulty sounding enthusiastic:

(a) the whole notion of passive crossovers vs. active. Given the KEF engineers’ apparent freedom to build an optimal speaker from the ground up, they are still constrained commercially by the convention of having to use passive crossover filters. And their arguments against linear phase filters (which would solve a lot of their problems and make more of a case for active filters) seem half-hearted.

Ultimately, the way I see it they have a space age speaker that is limited by steam-age technology. You may disagree.

(b) they admit that bass reflex (ported) speakers do not behave well in terms of time domain response and other difficulties, suggesting that 100l enclosures (about the size of my woofer enclosures) would be a ridiculous size, but that they would perform well. A more “reasonable” size of 15l requires the use of a port. The analysis is very detailed, but presumably this does not actually make the problem go away! Ditto giving the user the option of whether to use a full-blown port or an interchangeable reduced-strength version – in fact, on the larger models there are two ports per speaker, each of which can undergo this change, so there are several permutations for the user to try. Surely this means that one of them will be optimal..? I would, ultimately, say no – but you may think that my holding such a critical opinion of an aspect of this engineering tour de force is laughable, of course…


Going backwards…

One of the running themes of this blog is the observation that the hi-fi industry is going backwards: it reached sonic perfection (almost literally) in digital audio, yet most audiophiles now aspire to own ever-more ‘retro’ hardware (“My digital system is OK, but not as good as vinyl, obviously”, as one person told me) and they want to hear recordings via the media of the past. We have had valves and vinyl for a while, then the mono cartridge, and we may be seeing the first stirrings of the mechanical-only movement that I thought I was predicting a while ago.

In this piece, the writer is squarely in the hi-fi mainstream in his certainty that vinyl is superior to CD:

Maybe I’ll buy an inexpensive CD first to see if I like his albums a lot and then upgrade to the vinyl…

But he then goes on to describe the joys of the mechanical-only playback system:

When I play 78s for friends, I sometimes see a look of confusion on their faces as they somehow expected a high fidelity stereo recording to come out of the monaural gramophone. Instead they hear this loud-but-small music which somehow punctuates and fills the room, much in the same way my 5.1 surround system does.

I have to remind them that this is a different medium and you have to listen differently. You have to be involved with it, getting up every few minutes to switch discs, needles and cranking up the motor.

I can enjoy a mono 78 RPM disc of Duke Ellington from the 1920s just as much as Steven Wilson-produced 5.1 remix of Yes’ Close to the Edge or Beck’s Morning Phase on 180-gram vinyl made at a fancy European audiophile pressing plant in 2014.

Clearly, people are craving less ‘sterile’ experiences in their lives, and I think the actual music may only be tangential to this; the collecting of 10,000 LPs and the messing about with old hardware is the bulk of ‘the experience’.

There may also be something else: at the real technological cutting edge (not that many audiophiles ever get anywhere near it at overall system level) absolute progress in audio quality is now more-or-less impossible. By going ‘retro’, a very attractive prospect presents itself to high end manufacturers and hobbyists: the chance to apply modern techniques to technology that was developed using slide rules and old school manufacturing methods. If, at a stroke, we simply define vinyl as inherently better than digital, then absolute progress is suddenly back on the agenda! Technology has progressed in the few decades since vinyl was ‘put on hold’, so we can now start designing and manufacturing low cost turntable parts using CAD/CAM, regulating platter speed with microcontrollers, making things out of carbon fibre… because we can. And so on.

Many ‘retro’ audio products are amenable to this ‘progress’. For example, speaker horns can now be 3D printed to exact mathematical shapes derived from simulations (- it doesn’t mean they’re valid, however; they will no-doubt still sound wrong!). It is an engineer’s playground that can be extended as required by simply re-defining various old technologies as inherently superior to the misperceived sterility of solid state, digital audio.

Later with Jools has still got it…

Curtis Harding and band.

Curtis Harding and band.

As ever, last night’s programme provided the nearest thing to seeing some great artists close up and live in a very clean setting. The sound is excellent, really putting across an impression of ‘live’ – wonderful bass sounds from Curtis Harding’s band, Paul Weller and the rest. The camera work is superb, as is the quality of the image and the lighting – the makers of this programme have always maintained the 50Hz frame rate for maximum ‘live-ness’. On a decent telly, you are there.

I’m not keen on Jools Holland’s predilection for flabby soul/big/swing band music, and my other complaint is that the programme could do with a hint more edge now and again – it feels relentlessly and self-consciously inoffensive with its carefully-chosen ‘audience in the round’, like a party political conference. But on the whole, I’m still glad it’s there after 23 years. Long may it continue.


It seems that there is a new smart interface for your music collection, mentioned here and here.


I’ll bet it is good if you like that sort of thing – but worth $119 a year? You decide.

Many’s the time with Spotify I have wished that it could simply display a full screen image of the album art while playing – not much to ask, but seemingly too difficult to arrange. Not to mention being able to sort search results, a useful facility that seemed to disappear with an update some time ago and is bitterly regretted by the users – but bizarrely lives on in the Linux version (I have been trying to work out the story behind why they thought it was a good idea to remove it, but can’t!). Clearly, it must be possible to do something better in the non-Spotify world, and I have every confidence in roon.

But something caught my eye in the various mentions around the web: people are enquiring about roon’s sound quality, and no one knows, or wants to give them a straight answer.

Well let me do it: the sound quality will be exactly what you can get / are getting right now. There is no mystery. Digital audio is not mysterious. It is just numbers. A new user interface is not going to change the numbers. And unless something is very wrong, it is not going to change how the numbers are sent to your DAC. OK?

The Power of Ideas… to enrage audiophiles

I just had a somewhat abrasive online encounter. I had the temerity to comment on some blog articles about digital cables and found that what I was saying seemed to send people apoplectic with rage.


Basically, I asked: if digital cables are responsible for changing the sound in any way, then how could high quality online streaming services work at all? The signals are sent over long distances of dubious cable, non-audiophile optical fibres and satellites not even made of silver, and yet, supposedly (and actually), the signals emerge in real time, utterly perfect – except, that is, for the deleterious effects of that pesky final cable…

As always with this sort of idea or thought-experiment, I was told I was “missing the point” – the articles were primarily about cables’ effects on noise injection, hum loops, jitter and so on, so such “philosophical” arguments were irrelevant, they blustered.

But if we accept the notion that high quality online streaming is possible (audiophiles have no trouble accepting that TIDAL is “CD quality”), and that it is independent of the types of cables in the global internet (changing dynamically from moment to moment), and indeed is indistinguishable at the DAC from a network-based CD drive (for example) on our local network, then the implication of the ‘noise’ agenda must be that all the ‘noise’ from the thousands of miles of bog-standard cable and bog-standard digital gubbins along the way can be removed before it even reaches our network. So why can the DAC not incorporate this 100% noise blocking function itself? If it can (and it can) then the final cable in the chain takes on only the same significance as any other of the myriad cheap, long cables in the chain i.e. demonstrably none whatsoever. And, indeed, that was the whole idea of digital audio in the first place – an idea that has somehow become forgotten along the way.

Of course I accept that some digital audio implementations are poorly-designed and could, indeed, be susceptible to noise injection, hum loops and so on. Some may even suffer from power supply noise related to the digital signal and “how hard the chips have to work”. But if so, then messing around with cables is a red herring; trying to fix a fundamental problem with a sticking plaster. But even this overstates the case: at least a sticking plaster is designed by clever people who understand the problem. It is effective at what it does and doesn’t pretend to work simply because it is made of a certain material or incorporates an ancient Celtic weave. A common mistake is to believe that audiophile hardware is ‘higher quality’ than standard, but that rationalists don’t believe it is worth using. No. The truth is that rationalists don’t even believe that it is ‘higher quality’. Probably the opposite. It may be more expensive. It may use materials that are sacred to audiophiles. But it is just a manifestation of ignorance and magical thinking, and is worthless or worse. A more expensive cable can/will not fix the problems with your defective DAC. The only way to fix the problem for real is to design the electronics competently, and to design the last digital node to block ‘noise’ in the same way as earlier nodes can, apparently, block all the noise of the entire internet.

The unpalatable truth is that if you hear differences in your system when you change your digital cables you are either:

  1. imagining it, or
  2. the owner of hardware that is defective (by design).

I would bet that (1) is the more common. Given a suitable measurement setup whose resolution equalled or exceeded the resolution of your audio DAC, you could verify your system’s immunity by feeding in known digital test waveforms and checking that what came out of the DAC was always the same regardless of cable and any other upstream hardware. This idea, too, was met with seething fury!

Maybe I have realised something: many people simply cannot process “philosophical” ideas. The only way they can get a handle on them is for someone first to ‘downsample’ them into a form they are comfortable with:

  • brand names and products
  • industry gossip and hero-worship
  • low level engineering trivialities as a substitute and/or smokescreen for genuine ideas
  • shop-floor nuts and bolts

But this is a lossy process. It is impossible to ‘upsample’ the low level tittle tattle back into the world of ideas. Any attempt to do so, or a refusal to ‘downsample’ in the first place, causes panic, abuse, then meltdown.

Music – where does it come from?

I just found a new chord sequence on the piano. Well, new for me. I am sure I must have heard it in some famous records, but I can’t quite dredge from my memory what they might be. But I found my fingers – at least six of them simultaneously – creating this rather rich progression, and that I further could embellish it with approximately the right notes from higher up the keyboard and it still sounded great. Just like real music, in fact. Fast or slow, low or high, with key changes, it all worked. I could have started singing and added another dimension to it, but just the basic sequence contained a world of melancholy, resignation, tension, resolution and elation. Or something like that. The point being that it came from nowhere, and that pulling it out from all the other nondescript things I was playing was an act of curation rather than the romantic notion of creation. Turning it into a full piece of music would be a case of building upon it, spinning some lyrics that fitted the images that the sequence conjured up in my head, and maybe mechanically and calculatedly applying a structure of verse, pre-chorus, chorus… middle eight…. etc. The composition could be given to a real performer who would, like an actor, put him/herself into character and emote their way through it. That would be one way of doing it. Presumably it could be done differently: starting with a great phrase in the lyrics, an interesting rhythm, an unusual sound, or with nothing but the objective of creating a song to fit a scene in a film or as an entry for an international televised song competition.

Just as with books or films, enjoyment of music requires some suspension of disbelief on the part of the ‘consumer’. They have to look past their knowledge of the behind-the-scenes stuff and believe that it was created spontaneously by an individual or group of gifted people, or even to believe that it emerged fully-formed without human agency. Surprisingly, it seems that people are able to do this, even if they are music creators themselves.

Recently, I went to see a well-known rock superstar in concert. Well, more of a ‘polymath’ superstar. He is well known as having a strong work ethic, and perhaps this spoiled my enjoyment of the show. I found myself watching and listening to his piano playing and thinking how simple it was, and perhaps how similar to my own doodling on the keyboard. I then considered how the dour, brooding songs were the result of hundreds of hours of ‘work ethic’ and that, even then, not much happened in them. Suddenly they didn’t seem so great…