Tuesday, February 20, 2007

$13,000 speaker cable!

Save us from Audiophiles!
John Dunlavy, who manufactures audiophile loudspeakers and wire to go with it, does think questioning is valid. A musician and engineer, Mr. Dunlavy said as an academic exercise he used principles of physics relating to transmission line and network theory to produce a high-end cable. "People ask if they will hear a difference, and I tell them no," he said.
Mr. Dunlavy has often gathered audio critics in his Colorado Springs lab for a demonstration.
"What we do is kind of dirty and stinky," he said. "We say we are starting with a 12 WAG zip cord, and we position a technician behind each speaker to change the cables out."
The technicians hold up fancy-looking cables before they disappear behind the speakers. The critics debate the sound characteristics of each wire.
"They describe huge changes and they say, 'Oh my God, John, tell me you can hear that difference,'" Mr. Dunlavy said. The trick is the technicians never actually change the cables, he said, adding, "It's the placebo effect."

I remember BBC Research Department did a similair set of tests in the late eighties and concluded that the best paid ears in the industry (with the best amps and speakers) couldn't tell the difference between 10A mains cable and very expensive OFC cable. Around the same time Practical Electronics magazine did a blind test with the editors of What Hifi and HiFi World and they concluded that the mains cable they'd taken off a lawn-mower was the best sounding cable!

With all this in mind I'd point you at previous posts;
Audiophile at I-Like-Jam and Why do people have to have their say?

Friday, February 16, 2007

I always hated vinyl

Even when I was a kid watching my parents putting vinyl on the turntable I thought there had to be a better way of reproducing music. When I started working at the Beeb I had a couple of professional friends who held the view that vinyl is the better medium for enjoying music. I've always held the opposite view - to me when I listen to music from CD or DAT it sounds like what you hear in the control room of a recording studio. It sounds like what the band/engineer/producer hear, and as such it's what I'd like to hear. Have you ever been to a vinyl mastering plant and seen what gets done to the master tape while it's being prepared for transfer? The RIAA characteristic is pretty brutal!
I did make a DAT recording (on a Sony PCM7030) of the same piece of music from both vinyl (on a Pink Triangle turntable) and CD. My 'audiophile' colleague didn't realise that both pieces of music were coming from DAT - he correctly identified the source of each, but evidently the DAT was able to capture from the Vinyl whatever it was he loves so much. We were doing this blind test using DynAudio speakers and matched amplifier (whole lot £5,000) - as an aside how do people with sub-£1,000 set-ups in their living room make these quality judgements?
My own thought is that people like the sound of vinyl - all those second-order harmonics and flabby LF response sounds comfortable to them in the same way that Technicolor movies from the forties and fifties are nice to look at - but Clark Gable never really looked that colour ! I don't criticise that but I do think that the tag HiFi should be reserved for DAT / CD (even though a 'Hi-Fi' vinyl deck costs more than a thousand whereas a decent CD player is only a couple of hundred).
You can't get away from the fact that CD has a dynamic range of 96dBs and is flat to 22Khz - signal to noise and bandwidth are the things that you hear when they aren't all there, and with vinyl recordings they aren't!

Anyhow - I remembered a couple of truly bizarre record players - one I'd seen and one I'd only read about. In the early eighties (a couple of years after Sony launched the Walkman) there was the SoundBurger - It was a battery-powered gadget that wrapped around the record and allowed you to enjoy your (delicate!) records on the move. It had a belt clip and I actually saw someone walking along with this one their hip with the record spinning - a bit like Boadicea's chariot coming towards you!

The other one was Crysler's in car record player - I can only imagine how much it jumped and skipped. A further problem was that it exclusively used Columbia's 16⅔ RPM format - so you were pretty much locked in to their releases. A kind of early DRM - iTunes would be proud!

Wednesday, February 14, 2007

World’s First Commercial Quantum Computer Demonstrated

I did a degree in maths & programming in the eighties and had a fabulous time - however, one of the subjects that came up often (particularly when doing cryptography) was that mythical beast the quantum computer - tutors would say things like ¨...so you can see all possible solutions are computable at once¨ - which always made me ask how you'd separate the correct answer from all possible answers. In terms of crypto it seemed like you were just re-iterating the size of the key-space. Anyhow - D-Wave Systems of Canada have launched a processor that uses superconduction to contain the quantum elements - that's one of the problems - how do you shield the quantum processes from the 'noise' of the universe? Traditionally research has focused on using laser interference to create quantum states but the accuracy of such rigs makes them impractical.
Anyhow - the article on Wikipedia got me thinking;
...the contents of the qubit registers can be thought of as an 8-dimensional complex vector. An algorithm for a quantum computer must initialize this vector in some specified form (dependent on the design of the quantum computer). In each step of the algorithm, that vector is modified by multiplying it by a unitary matrix. The matrix is determined by the physics of the device. The unitary character of the matrix ensures the matrix is invertible (so each step is reversible).

So I think I understand that to mean that the array contains complex values with both size and direction - but in eight dimensions - wow! The unitary matrix which is the second parameter in whatever function is used (¨determined by the physics of the device¨) and the function is two-way.
Upon termination of the algorithm, the 8-dimensional complex vector stored in the register must be somehow read off from the qubit register by a quantum measurement. However, by the laws of quantum mechanics, that measurement will yield a random 3 bit string (and it will destroy the stored state as well). This random string can be used in computing the value of a function because (by design) the probability distribution of the measured output bitstring is skewed in favor of the correct value of the function. By repeated runs of the quantum computer and measurement of the output, the correct value can be determined, to a high probability, by majority polling of the outputs. In brief, quantum computations are probabilistic

That seems almost (but not quite) as much of a cop-out as my undergraduate lecturer!
I suppose that if you took a guy doing my job from fifty years ago he'd have trouble understanding not only the technology we now use (digital over analogue, compressed video, digital control systems over servos etc.) but he'd be hard pushed to see why we'd want to do things the way we do. I think I'll feel the same way about quantum computers when they eventually make it to prime time.

Friday, February 09, 2007

Cutting the cost of computing

My institute's magazine plopped onto the doormat yesterday and I was pleased to see this article about the one laptop per child project. I blogged about it previously.
The piece goes into more details about the number of territories who are bypassing traditional business IT models and adopting a more open source model. It reminded me of something that's been evident in India with their post-production market. Essentially they avoided the first couple of generations of non-linear editing technology and pretty much all of the developments of the nineties and have plunged into data-driven workflows (particularly DI for film). I wonder if this will be mirrored in other areas of technology as what was the third world becomes the tiger economies of the twenty-first century?
Essentially they let the USA/Europe make the mistakes and when the technology has been shaken down it's ready for them.

Monday, February 05, 2007

My server's autumn years!

My fileserver at home (the machine that carries this venerable blog amoungst other websites) has been a faithful box - bought in 1998 it is a dual-P2 motherboard (screaming along at 450Mhz!) it was the family's PC for a while but for the last six years it's been sitting in the cellar largely ignored! Aside from a couple of upgrades (mirrored disk, the odd clean) it's run 24-7 since 2001. Initially it wasn't just a web, FTP and Windows fileserver but it was our router/firewall/internet proxy. It was our mail and DNS server, it hosted our Skype-phone adaptor and did other things (scheduled backups etc). As cheap, dedicated network devices have become sensibly priced it's load has been lightened - first it gave up it's router/firewall duties when I bought a DLink router (and then replaced it for a wireless box), then my Belkin Skype handset relieved it a bit more. Now all my network backups are done by my little NAS box and since it's also an FTP and webserver my server may give up all serving duties. The last thing it's used for is as a player for internet audio and our music collection/podcasts in the kitchen - having tried a couple of the stand-alone devices that do this I'm not sure my server is due to decomissioning yet.
I've even shifted my email server needs back out to our ISP because they have much better spam filtering and mailboxes you can retrieve anywhere via a good web portal.
Anyhow - what has spured thoughts of ditching old faithful has been the failure of the RAID-1 disk set today. I'd been using the Windows mirroring which seems unable to recover from corruption without a bit of intervention. If you're lucky it's only a reboot, but often it's swapping the drives around so that the uncorrupted side of the mirror can re-boot the server. Now I know it's the Windows server software solution and if I was serious I'd stick a RAID card in there but it's a pain. So, over the next few weeks I'm going to migrate everything off this box on to my NAS and see how it all handles it. The good thing is I can switch the sites/blogs etc back and forth merely by changing the port routing in my DLink router.

Thursday, February 01, 2007

Spam gibberish

Have you ever wondered where junk emailers get that random English text they stick at the end of messages? It looks like it might mean something and although you understand what the individual phrases mean it's still nonsense - a bit like Timeout magazine or anything written by Will Self!
Anyhow - while reading some Newsgroup entries from 1999 I came across this chap - his name is Alan Earle and I'm sure it's just the output of some (very poor) natural language processing project - have a look at this and see if you know what he's banging on about;

They allocated although after we had a cochannel I will get their sophistication, until they exploited it to reclaim him. I cultivated before that I had every nuisance they could solicit its comprehension, before they obstructed him to curtail us.

He's all over the American political newsgroups from the late nineties.