The music goes round and round and comes out backwards

16 May 2012 — dan

A reader writes:

Sometimes when I plug in my headphones it seems as if I'm not receiving any vocals. Its still stereo, but I find that the headphone jack isn't completely in. What's going on here? And why does it work so effectively at removing vocals?

Simon

The quick answer: You're hearing the two stereo channels mixed, with one of them out of phase with the other.

I can't for the life of me figure out how this happened, though. In the interminable rambling below I talk about a couple of other crossed connections that can, and often do, happen, but unless there's a bit of wire stuck in the headphone socket or some other such oddity, I don't know how you could have the exact symptoms you report. Unless, of course, what you think you're hearing isn't what's actually happening, which is eminently possible since the ear is as easy to fool as the eye.

Anyway, mixing one stereo channel with an opposite-phase version of the other channel means that any component of the musical mix which is essentially monophonic - in the middle of the stereo "soundstage", the same on both channels - will be cancelled out.

Singing in popular music is, usually, pretty much in mono in the middle of the stereo mix. So mixing one side with a phase-flipped version of the other side will cancel out said singing; all you'll hear of the singer is any stereo reverb or difference in volume between the two sides (a.k.a. panning).

This technique, called Out Of Phase Stereo or OOPS, is used in this simplest form by old and/or cheap karaoke machines that let you "mute" the vocals on normal music, so you don't need a special vocal-less karaoke version of every song.

Simple OOPS doesn't work very well, because vocals are seldom exactly in mono (they usually have some stereo reverb, for instance), and if any other component of the mix - drums, bass, whatever - is also mono, then that'll be muted too. Smarter OOPS vocal-muting tries to identify and mute only the vocals, based on the pitch and possibly even the timbre of the sound.

This weirdness can come about because headphone plugs use TRS (Tip, Ring, Sleeve) connectors. TRS connectors come in a variety of sizes - the big old-fashioned 6.35mm (quarter-inch), the ubiquitous modern 3.5mm (eighth-inch), and the usually unnecessary and irritating 2.5mm (3/32 or 1/10 inch, depending on who you ask). All three-contact audio TRS connectors are, or should be, wired the same way; the tip of the plug is left channel, the ring is right channel, and the sleeve at the base of the plug is a shared ground.

(This sort of cylindrical plug connector should only be called "TRS" if it has these three contacts. Mono-audio cables with the same sort of plug, like for instance guitar leads, omit the ring contact and should therefore be called just "TS" connectors. Connectors with two ring contacts, as for instance used for stereo headsets with a microphone, should be called "TRRS". Sometimes you'll see any plug of this basic form called a "TRS" plug, though, regardless of how many contacts it actually has.)

Most headphones today have a 3.5mm plug; fancier ones...

Sennheiser plug

...come with a 6.35mm adapter for it, too.

Some headphones mix it up a bit. One of these Sennheisers has a simple 3.5mm TRS plug on both ends of its cable, so you can very easily and cheaply replace the cable if it's damaged...

Sennheiser cable plugs

...but the other has a 3.5mm TRS on one end of its cable, and at the other end the cable splits into a pair of 2.5mm TS plugs, one for each side of the headphones.

If a TRS plug isn't fully inserted, contacts on the plug can touch the wrong contacts in the socket.

(This characteristic makes this shape of plug a bad fit for many applications. I once bodged up a two-voltage power-supply connection for an external SCSI drive box for, of course, my Amiga, using a 6.35mm TRS plug and socket. I avoided the dangers of connecting one voltage to the other's contact and the other voltage to the ground contact by only connecting or disconnecting the power supply when everything was turned off. Or, at least, connecting or disconnecting it really fast.)

A partially-inserted TRS plug could, for instance, leave the tip contact on the plug touching the ring contact of the socket, and the plug's ring contact not touching anything, and the sleeve of the plug still touching the sleeve of the socket, because the sleeve is much longer than the other two contacts. This sort of mis-connection will give you the signal meant for your right ear in your left ear, and no sound from the right side of the headphones.

(The sleeve of the plug is connected to the braided or foil shield of the cable, and any or all metalwork on the plug that is not the tip or ring contact will also be connected to the shield - it's all one big sleeve contact, basically. TRS sockets almost always work the same way; the socket has small tip and ring contacts, but the rest of the socket's metal is all sleeve. This makes it very easy for the sleeve of plug and socket to remain connected when the plug isn't all the way in, and if the plug's a long way out of the socket it also makes it pretty easy for the plug's ring contact to touch the socket sleeve contact.)

I encourage readers, by the way, to try this out yourselves; it's pretty much impossible to hurt your headphones or anything you plug them into by only plugging them in half-way. So do that, especially if you find my interminable blather confusing, or just want to see if you can create Simon's symptoms for yourself.

Another mis-connection could have the plug-tip touching the socket-ring, and plug-ring touching socket-sleeve. Now you'll hear the signal meant for the right side through both ears, but it'll sound weird, because it's out of phase, as mentioned above.

This is because the left and right "drivers" of the headphones (the electromagnetic transducers that actually make the sound) are, with this mis-connection, now wired in series, with the wire going "out" of the left driver that's meant to connect directly to the sleeve contact instead only being able to connect to the sleeve through the right driver and the plug's ring contact, thereby feeding the right driver "backwards".

This causes the right side to be out of phase - when the left driver is moving toward your head, the right one should be too, but now its phase is inverted and it's moving away.

There are two reasons why I'm rabbiting on about this stuff at such outrageous length. The first is that basic audio cabling like this is something that almost everybody has to deal with, and it pays to know what connects to what even if you don't intend to be soldering up any cables of your own - though basic soldering is easy to learn, cheap, and can save you quite a bit of money.

(Just yesterday, I turned a couple of not-that-cheap Apple laptop power supplies, one electrically dead and the other with a fractured and fiendish-to-repair MagSafe plug, into one working power supply with an extra-long cable. Even the dodgiest off-brand MagSafe power supplies are about $US20; a genuine Apple one is $79. With basic soldering skills and equipment, this sort of thing is a literal five-minute job.)

The second reason for this ridiculously large post is that phase problems are actually very common in home audio, and not only among people who fix their own headphones and get one set of Profanity-Allowance-consuming minuscule wires backwards.

People have been creating phase problems ever since the invention of stereo, occasionally by mis-connecting a turntable cartridge, but usually by wiring one of their stereo speakers the right way around (red terminal on the amplifier to red terminal on the speaker, and black to black) and the other the wrong way (red to black, black to red). In this case, each speaker actually is playing the signal that it should be, but one is phase-inverted.

(It doesn't really matter whether you've connected red-to-red or the other way around, as long as both speakers are the same. In theory, having both out of phase with the way they should be, but in phase with each other, could cause an audible difference, but in practice it's only detectable by golden-eared audiophiles who see no need for tiresome things like blinded tests.)

If you've got two working ears, you definitely can hear when stereo has one side out of phase. It's hard to describe, though; it's sort of like having a head cold that's blocked one of your Eustachian tubes but not the other, or how things sound when an air-pressure change has popped only one of your ears. Here's a page that explains this, with nifty audio samples including one (MP3 link) that should sound mono in the first half and out-of-phase pseudo-stereo in the second half.

Out-of-phase audio sounds different on headphones and speakers, because of the basic differences between the two devices. Headphones deliver pretty much pure left-signal to your left ear and right-signal to your right, but each of your ears hears both members of a stereo speaker pair, plus umpteen reflections and resonances from the room you're in.

For this reason, if you're listening to stereo speakers with one side out of phase, there will be strangely little bass, because low-frequency sound has a long enough wavelength that the out-of-phase speakers can mix their sound even if they're separated by a few metres. Higher-pitched centre-mixed components of the music won't cancel as much, though.

Just to make things even more complicated, sometimes it's good to reverse the phase of a subwoofer or surround speakers, to compensate for subwoofer location or the distance of the surround speakers. There's often a hardware switch on a subwoofer or a configuration option on a surround receiver that'll let you do this, or of course you can just switch the wires around or make a crossover RCA cable.

There are also some stereo recordings on which phase reversal is undetectable, because the two channels share nothing at all. Many early stereo rock tracks are like this, and are pretty much intolerable to listen to with headphones because the stereo mix puts each instrument entirely on the left or right channel. Ringo and Paul on the left, John and George on the right. Nobody minded this very much at the time, because almost everyone heard this music in the mono mix, but to make these tracks listenable with headphones you need a fancy headphone amplifier, or music-playing software, that has a "crossfeed" control, to deliberately mix some right into the left and some left into the right.

Out-of-phase mono - the same signal on both sides, but one way round on the left and the other way round on the right - kind of sounds like stereo, because you genuinely are hearing something different on each side. So what I think you, Simon, are hearing from your partially-connected headphones is a mixture of left and right, with one side's waveform inverted, the resultant mono signal being heard one way round on the left side and the other way around on the right. I just can't figure out how you could electro-mechanically get this to happen by only partially plugging in the headphones. I presume there's one contact on plug or socket that's touching two contacts on socket or plug, but I don't know which.

It is, again, entirely possible that you're not perceiving what's going on correctly; psychoacoustic effects can be powerful. But perhaps I'm just insufficiently imaginative. Any ideas (or experiment reports!), commenters?

Posted in Electricity, Electronics, Music. 8 Comments »

Horniness

13 March 2012 — dan

A reader writes:

Why do horns make things louder?

I mean, I accept that they do, on gramophones and megaphones and PA speakers at the train station and brass instruments and so on, but what's actually going on there? Why does the sound of your voice get louder just because you're holding a conical thing in front of your mouth? Is it just making it more... directional?

Dennis

The great problem of audio production, and audio reproduction too, is coupling the sound-producing thing to the sound-transmitting medium, which is usually air.

Air is very light. Most things that make sound are, in comparison, very heavy. The moving parts of loudspeaker drivers, the strings of a violin or piano, the lips of a trumpet-player who's blowing a sort of highly controlled raspberry into the mouthpiece of the instrument; all very very heavy, compared with air. All not good at moving lots of air, which is what you want your sound-making thing to do. Wave a brick around in the air and you'll invest a lot more energy in accelerating and decelerating the brick than you manage to impart to the air.

One way of solving this problem is to make your speaker driver very light too. Electrostatic speakers use a big flat sheet of super-thin plastic as a driver; the sound-producing element in a plasma speaker is made out of ionised air (or other gases, if you're a big wuss who doesn't want ozone poisoning).

Horns are a simpler way of solving, or at least reducing, the coupling problem. When you put a heavy-compared-with-air vibrating object at the small end of a horn, the only air it can move is the air right in front of it at the small end. Moving this air is still pretty easy, but the restricted air's mechanical "impedance" is nonetheless quite a bit higher than it'd be if it were unconfined.

As sound pressure waves move down the horn, the gradually widening shape of the horn (for loudest results, an exponential curve) allows the small amount of higher-pressure air next to the driver to transfer its energy to a large amount of lower-pressure air. The end result is that more of the energy of the driver ends up as sound waves.

A sealed-box loudspeaker has an acoustic efficiency - the amount of the input electrical energy that comes out as sound energy - of about one per cent, at best. Horn speakers can manage thirty per cent without much trouble, and quite a bit more if you design them for loudness rather than fidelity. Take the horn off a phonograph and you'll have to put your ear right next to the diaphragm to hear much of anything, but with a big horn on it, a wind-up phonograph making sound by scraping a needle over a disc of shellac can legitimately be described as quite loud.

(Some phonographs let you remove the horn, or never had a horn in the first place, and allowed you to listen through one or more rubber tubes that went to a headset of some sort - essentially, primordial headphones. This allowed you to listen to your records in privacy, albeit with weird stethoscope-y sound colouration on top of the lousy fidelity of the phonograph system in the first place.)

Outside of Physics Experiment Land, acoustic horn design and implementation has many engineering tricks. For instance, modern horn loudspeakers usually have a horn throat that starts out much smaller than the diaphragm of the actual driver, which may be in its own actual rectangular speaker box stuck on the small end of the horn. There are also horn loudspeakers, like the legendary Klipschorn, that use various workarounds to fold something that acts somewhat like a horn into a speaker that can be mainly built out of flat wooden panels.

Also, the lowest bass frequency a horn can reproduce is determined by the size of the mouth of the horn; that's why public-address and hand-held megaphone speakers always sound tinny. Speakers like the Klipschorn have their horn mouth on the back of the enclosure, and are meant to be shoved into the corner of a room, so the walls behind them can provide a bit more effective horn size. Horn loudspeakers are also deliberately designed to be further away from an ideal horn shape than is strictly necessary, to balance the efficiency of the horn with the hard bass cut-off that a "pure" horn, with a mouth small enough to fit in a room, has at low frequencies.

The old phonograph horns have been reborn, too, as "amplifiers" for MP3 players and cellphones. The phone, MP3 player or ear-bud headphones plug into the small end of a horn, and suddenly the tsss-tsss-tsss of someone else listening to their iPod on the bus turns into actual music.

Some of these devices are very fancy and very expensive, but if you search eBay for "amplifiers" for MP3 players you'll find lots of cheerful-coloured horn doodads among the actual electrical amplifiers. The going rate for a combination iPhone stand and horn "amplifier" now seems to be about two bucks delivered.

Psycho Science is a regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

Posted in Music, Psycho Science, Science. 1 Comment »

Psychoacoustics again, again, and again

4 September 2010 — dan

Today's addition to my ongoing Psychoacoustics Archive comes courtesy of Ben Goldacre.

When listening to the exact same recording, apparently being played by similar-looking but differently-attired female violinists, evaluators consistently thought the music was better when the performers were more "professionally" attired.

This turns out to be an entirely uncontroversial finding. Until I read this Bad Science post, I didn't know that orchestra auditions are now usually blinded (the auditioner plays behind an opaque screen). This is because unblinded auditions have repeatedly been demonstrated to create unfair discrimination, even when frank racism is not involved. Even listeners who apparently honestly don't consciously believe that, for instance, women are worse musicians than men, will often rate female performers lower. And that's before you even start to consider attire and physical attractiveness. (Witness the recent global astonishment when an unattractive woman, apparently against all that science and art has ever told us, turned out to have a decent singing voice.)

The evaluators in this latest study were just music students and professional orchestral musicians, though, not audiophiles. I'm sure audiophiles would have done much better.

Posted in Music, Science. 10 Comments »

From the "any publicity..." file

23 August 2010 — dan

Imagine my delight at receiving the following:

From: "Clink Admin" >admin@clink.com.au<
To: dan@dansdata.com
Subject: A review?
Date: Sat, 21 Aug 2010 15:21:37 +1000

Hi Dan,

I was wondering if you would do a review of something on my website, address in signature.
Not sure if anything on there is along the lines of stuff you would normally but think there may be a couple of items that fit in.

Would love if you would do a review of my Vortex Analogue Interconnects, these have proven very popular cable.
http://clink.com.au/audio/stereo.htm (bottom of the page)
So would be great to get an independent and unbiased view of these.
Would only ask you to do a cable review though if you feel it is something that has an impact on audio quality.
If your of the school of thought that they have no impact then prefer not to have a review done as it would be very short, probably in the under 10 words variety of short.

Gregory
Cinema Link, Sales
675 Elizabeth St
Waterloo NSW 2017
Ph: (02) 9698 4959
www.clink.com.au

[There was a bit more to this e-mail; I've corresponded with Gregory previously. He asked if I'd like to check out one of his HDMI switches, which I don't actually have the equipment to test but which seem quite handy; by linking to them and other pages of his without so much as a nofollow, I hereby repay Greg for what's going to happen to him in the rest of this post!]

My answer:

Yeeeahhh... you haven't read much of my site, have you :-)?

(Or this blog, for that matter.)

It's the "school of thought" part that I think is the problem. There's no need to separate people into pseudo-religious "schools of thought" over a question that can be settled by scientific means.

We know, with the same certainty that we know that the GPS system and personal computers work and for many of the same reasons, that none of the conventionally-measurable electrical characteristics of analogue cables have any effect on the sound. Well, except in particularly pathological cases where some truly bizarre cable architecture adds substantial reactance or something, in which case it only makes a system sound better if there was something wrong with the system in the first place. Like, your speakers have 14 drivers wired in parallel and thus have far too little impedance for your amp to happily drive, so hooking them up via carbon spark-plug leads or something that add a lot of resistance un-ruins the sound.

(See also those occasional fringe-audiophile products that are actually quantifiably bad, like
this amplifier, plus a veritable cavalcade of dreadful valve amplifiers. All of which have users who insist that they sound GREAT.)

[Oh - in case you're wondering, yes, Cinema Link have fancy digital cables, too...]

The analogue-cables-sound-different response to the electrical-engineering argument is to say that DC-to-daylight frequency and phase analysis just doesn't measure some special something that they know when they hear it, science doesn't know everything, et cetera.

But a vanishingly small percentage of the people who say this ever bother to do even a simple single-blind test to see if they, themselves, can actually hear any difference between their special cables and lamp cord. Such tests really are not difficult to do at all - all you need is a trustworthy friend to flip coins, swap cables and make notes, some very elementary experimental design, and a spare afternoon - but they're amazingly unpopular. Un-blinded tests remain immensely popular, but it's trivially demonstrable that those don't work.

This is my favourite recent example, but there are countless others, covering the entire breadth of live and recorded sound. Vision and hearing are subject to an immense amount of processing by the brain before consciousness gets to perceive them.

(Another favourite of mine: Famous concert violinists are often certain that they can tell the difference between a priceless antique violin - especially if it's their Stradivarius or whatever - and a high-quality modern instrument. But when you do a blinded test, the results, once again, drop to chance levels! They can probably pick the Strad blindfolded if they're actually holding it in their hands, but that's all.)

Some audiophiles go so far as to say that no matter how perfect the experiment design, with no possibly-sound-colouring ABX switchboxes or skull-resonance-changing blindfolds involved, these sorts of differences just can't be detected by science, in the same way that God will never permit Himself to be detected by scientific investigation. Exactly how these people figured out that the new cables sounded better is, in these cases, something of a mystery.

(The people who insist that cables need "burn-in time" have a particularly neat way out of blinded tests; they can just assert that the... phlogiston, or whatever... leaks out of burned-in cables when you disconnect them. But I'd be willing to bet quite a lot of money that swapping out their expensive burned-in wires for hidden $2 interconnects and bell-wire speaker cables would pass entirely unnoticed.)

I'm inclined to go easy on people who buy fancy cables and reckon they sound good. We all fool ourselves frequently, which is why science is so important, but a fooling of oneself that leads to essentially harmless happiness is not a major crime.

But I really must insist that people who're in the business of making and selling fancy cables have no right to make any claims about the "sound" of their products, if they haven't at least hired a few first-year electrical-engineering students to spend a day doing an independent test.

If, when blinded tests were done, they at least reasonably frequently showed that fancy cables sounded better, then it'd be no big deal to sell such products without doing the tests yourself. But what we instead keep seeing is that in a blinded test people can't tell the difference between Monster Cables and (literal) coat-hanger wire. (Monster products may be overpriced and often sold in a blatantly dishonest way, but surely they ought to beat coat-hangers!)

Given this, I cannot help but consider the basic rationale for products such as your cables as being as unproven as the notion that a chiropractor can cure diabetes, or that all poor people are poor because they do not adequately desire wealth.

It's not the Middle Ages any more. We know where lightning comes from, we have machines that routinely fly hundreds of people thousands of miles in (relative) comfort, and our doctors have figured out that it's a good idea to wash your hands before operating. Every day, people in First World nations are surrounded by proof of the effectiveness of scientific inquiry that's so bright, loud and ubiquitous that we, apparently, have developed the ability to tune it out when it suits us. But that doesn't make it a good idea to do so.

You're not a quack, and I don't think you're a scam artist, either. Your cables aren't outrageously expensive relative to the price of the components and assembly - they might as well be free, when compared with the truly out-there cable vendors. And you don't sell $1000 power cables, either (...do you? Tell me you don't!). But this doesn't mean that sending samples of new cables to your existing customers and using their testimonials in advertising is an acceptable way of proving your claims.

If testimonials were a good way of proving the scientifically dubious, I'd be torn between devoting all my time and money to Transcendental Meditation in order to develop the ability to fly and walk through walls, or devoting just as much time and probably even more money to Scientology in order to develop the ability to control space and time.

At the end of the day, I suppose you do end up with "schools of thought", but the members of those schools are not "people who reckon special cables sound better" and "people who don't" (or "people who reckon Uri Geller has paranormal powers" and "people who don't"; I'm sure you can provide many of your own examples). They're "people who believe this question is amenable to rational investigation" and "people who don't care".

You're allowed to not care. Everyone's entitled to his opinion. But nobody's entitled to be taken seriously.

Gregory replied:

Thanks for taking the time to reply in depth, and for the informative links.

I've taken a little more time this time to read some of the pieces on your site and understand a little more of your thoughts on audio cables.

So I'll take that as no, or at least I'll take it as something that would be detrimental to my business health.

To which I replied:

...and you are thus acknowledging that if you made an attempt to figure out if your fancy cables worked, you'd find that they didn't? :-)

[Greg's, regrettably, not yet found time to reply to that.]

As I said, for hi-fi this really doesn't make a whole lot of difference either way. Even the really wacky Shun Mook or Peter Belt (...or just about anything else that 6moons thinks is fantastic...) sort of hi-fi cultism doesn't really hurt anyone - certainly not by the standards of the usual kind of cult. Some nut out there has probably bought speaker wire instead of nutritious food for his children, but that is hardly a probable situation.

That doesn't mean that the same patterns observable in truly harmful things like crazy cults and medical quackery aren't valid when you see them in other contexts, though. One I find particularly common, which is very much on show in the audiophile world, is the peculiar and inexplicable situation in which the better you investigate something - eliminating extra variables, reducing experimenter bias, reducing the ability of subjects to fool themselves - the less effect that something turns out to have.

When "lousy test" shows "huge effect" and "better test" shows "medium effect" and "further-improved test" shows "not much effect at all", it may be that the latter two tests were false negatives.

But it usually does actually mean that "perfect test" would show "zero effect".

Posted in Electricity, Music, Science. 20 Comments »

Three-card Monte... with three queens?

31 July 2010 — dan

A reader writes:

I wanted to bring your attention to Dream Acoustics speakers. I'm hoping you might review some.

I bought a set on eBay recently.

I replaced the surrounds on my Logitech Z-5500s with these, thinking they would do music better, and actually I am really quite impressed!

$120 for five speakers, including "full range" (almost) tower speakers!

Anyway, there is tons of cheap gear on eBay, all under "Dream Acoustics". I would love to see you write up your opinion on it, as I know audio is one of your specialities.

Stephan

Well, this is a weird situation. It's sort of like finding someone pulling the Violin Scam, except they're not claiming the fiddle's worth more than $5.

I don't think it's at all likely that "Dream Acoustics", or the other companies whose products are functionally indistinguishable from the Dream ones, would ever send me anything for review. There's a whole gaggle of them - "Pure Audio", "Omni Audio", "Dynalab", and the list goes on. Collectively, they're often known as "white-van speakers", because classically they're sold, inflated prices, by scam artists in vans, to whoever they can flag down.

The Wikipedia article currently has a lengthy list of white-van speaker brands, as do other sources. Many white-van brand names are deliberately similar to the names of companies that make high-quality loudspeakers. Again, Dream Acoustics seem to be taking the high road here; they're not trying to sell speakers labelled "DunAudio" or "BJL" or "Woofdale" or "FEK" or some other brand you'd expect to see on a set of speakers in Grand Theft Auto.

The one unifying characteristic of all of these odd-branded speakers, of course, is that they are not actually very good. They're usually pretty nice-looking, but that's the most complimentary thing you can say about them.

If "Dream Hi-Fi" were to send me some of their speakers to review, I'd take them apart, photograph the humiliatingly small magnets on the backs of the drivers and the lightweight, under-braced enclosures (which may not have any damping material in them, not even a token handful of cotton waste...), and observe that speakers just like these have been made available to the public by blokes in white vans for many years now.

I've been hunting for people who've actually done acoustic and electrical measurements on these sorts of speakers, or better yet torn one down and looked inside, but unfortunately there's a pretty small intersection between the set of people who buy white-van speakers, and the set of people who know how to test speakers. A hi-fi outfit called GR Research, however, has looked at a few of them - but none of the articles are still on the GR Research site for some reason, so I had to dig them up from elsewhere, like archive.org.

Here's GR Research's piece about some "Dahlton" white-van specials, which the tester says have "the worst response curve I have ever measured on any speaker".

(Including, by the way, these "Digital Audio Titan Line Hammerhead Eagle iThrust 3810SL" white-van speakers he wrote a short piece about earlier. At the time, they had the worst response curve he'd ever seen. Another reviewer has suggested that one should expect these speakers to sound like a crate of donkeys falling down a staircase.)

The Dahlton speakers can, at least, manage the usual department-store-speaker big muddy 60Hz bass boom, provided you make sure to aim their side-firing bass drivers at a wall at the correct angle. (Bass response below the 60Hz resonance peak is pretty much zero.)

And yes, he opened the box, and found thin wood, no bracing, and no damping material. And a really cheap crossover - but at least there was a crossover, which is apparently not something you can necessarily count on in this sector of the market.

(Without a crossover, woofers will be trying to reproduce treble and overheating, tweeters will be trying to reproduce bass and distorting, and midranges will have both problems at once. Turn the volume well up and you will damage each driver in turn, starting with the tweeter.)

Oh, and apparently the Dahlton manual gives advice about bi-amping the speakers, but the speakers' apparently-electrically-separate terminals on the back panel are actually connected together inside the box. So anybody who actually tries bi-amping will probably blow up at least one amplifier!

There's also this piece (for some reason archived on someone's Comcast home page) about some "VMPS 626R" speakers, which are the worst speakers the GR Research guy has ever looked at that didn't (in this one case, at least) come from blokes in a van. Again, they've got lightweight cabinets with no bracing, but there is at least a tiny useless puff of damping material! The VMPS speakers also feature drivers that don't fit properly in the holes in the box, atrocious crossover design with slightly different components in each speaker, large changes in frequency response from small changes in listener position, and overall assembly quality that suggests that the people who put the speakers together were forced to do so in some sort of reeducation camp.

The difference between you, Stephan, and almost everybody else in the world who has bought speakers like this, is that you have not been ripped off. As you say, $AU120 (less than $US110, as of late July 2010) for five speakers is not a bad deal, even if the speakers aren't very good. As long as they don't have any of the special driver-popping, amp-killing features of the very worst of the white-van crowd - which even cheap eBay speakers really shouldn't have - you'll be fine.

I think this is a good opportunity for a further digression about the white-van scam. It's perpetrated every day in most, if not all, affluent nations, and it always works the same way.

There is, you see, a company that imports these could-be-mistaken-for-expensive speakers in great numbers for ridiculously low unit prices. The company does not sell the speakers directly. It instead - on paper, at least - sells them on consignment to a bunch of "independent contractors", who're the guys in the, usually white, vans. Those contractors then head out and look for suckers, spinning a story to explain why these super-expensive very nice speakers are so very cheap, today only, bargain of a lifetime, et cetera.

Perhaps they just fitted out a hotel or something and have one set of speakers left over, officially these lovely speakers are already installed along with all the others, the hotel's loss could be your gain, and so on. Or maybe these speakers, um, fell off the back of a truck into our van, mate, nudge nudge. There's almost always some sort of underhanded flavour to the story, as is the case with so many scams. One of the best ways to get money out of a mark is to make him think there sure is a scam going on, but he and the scam artists are in it together, ripping off someone else.

(People often expand this into the maxim "you can't scam an honest man", but that's rubbish. Of course you can scam an honest man. You just can't scam him with a technique like "would you like to buy this property which I strongly imply is not actually mine to sell?")

Officially, the speaker importers never tell the "speakermen" to do anything underhanded at all. They're just drivin' around askin' people if they'd like to pay $800, which is half the retail price, buddy, for sets of flimsy speakers that wholesale for fifty bucks.

Actually, the sky's the limit for the alleged "retail price" of these things. In the case of these examples....

...it's $3,659!

If you start haggling, the speakermen know they've got you. They can turn a profit from almost any final sale price, no matter how broken the mark believes the speakermens' balls have become. The only thing the speakermen have to do is remember to keep a straight face when they allow you to pay a mere $250 for those $50 speakers.

What usually seems to actually happen in the world of the speakermen is that the importers and the van men all get together at the beginning and end of each day and have themselves one of those SELL SELL SELL HAHA WE ARE THE MODERN HIGHWAYMEN STAND AND DELIVER scam-artist Come-To-Satan revival meetings.

Well, that's what I think you'd probably see if you hid a spy camera in the distribution warehouse (here's an actual hidden-camera exposé!). But if anybody ends up in court, it'll transpire that the distributors actually can't even clearly recall the speakermen's names, much less any information about what those crazy kids might have gotten up to.

The only speaker-scam van I can remember personally seeing was actually green, not white. White vans are apparently much more common than coloured ones, though, I presume because legit small commercial vehicles are so often white. Some white-vanners even go to the trouble of getting their dodgy speaker brand of choice painted on the side of the van - or, at least, printed on a big magnetic sign.

(I've probably actually seen many speaker-scam vans over the years, without knowing what they were. Only if the speakermen go for the time-honoured "shout at potential marks while you're all stopped at the lights" fishing techniques can you identify them in traffic.)

I think some really slippery crap-speaker manufacturers even made a few "genuine" speakers, which they sent to reviewers or put on display in a showroom... and then went into bulk production with their standard awful speakers, that resemble the good ones. I don't know whether any manufacturers are bothering with that now, though.

Getting back to the eBay speakers: The crucial difference between a $AU199-plus-delivery Dream Acoustics five-speaker set (the Buy It Now price seems to have gone up since Stephan bought his speakers), and their white-van brethren, is that the eBay sellers seem to be asking a quite fair price. The specifications are all outrageous fantasy, of course, but that's nothing new in the low-end audio market, and I think factory quality control is now good enough that the speakers do usually work, for suitably small values of "work".

(The current $AU199 Dream Acoustic 5-speaker sets claim a total power handling for the five speakers of nine hundred and fifty watts. Expect the voice coils to actually be slapping the end stops at maybe a twentieth of that power, not that this actually matters for even quite loud normal listening. The specs also shamelessly claim the main speakers have response from "35 - 22,000Hz". This is more bullshit, but it's the same bullshit you'll find on the spec-sheets for countless big-brand department-store speakers and amplifiers. My favourite example of this nonsense is the decorative response graphs printed on those plastic speaker-surround doodads for mounting six-by-nines on your sedan's parcel shelf.)

Shipping for a five-speaker set makes the bargain a bit less impressive. Melbourne metro delivery from "Dream Hi-Fi" is only $AU39 for a five-speaker set, but shipping to most other Australian capitals costs $AU79, and if you're out in the sticks a bit like me here in Katoomba, you're looking at $AU158. That's not a secret, though; just plug your postcode into the shipping calculator on their eBay listings.

(When I did a "completed listings" search on ebay.com.au, I turned up numerous five-speaker Dream Acoustics surround systems that've auctioned for little more than $AU100. That low-low-low sale price can be considerably pumped up by shipping charges, but if the all-told price works out at less than $AU40 per speaker, it's difficult to complain.)

I think I should also mention that you don't have to troll the lowest-priced eBay dealers or wait for some guy in a van to yell at you if you want to buy some crappy speakers. I mean, look at these preposterous Kenwoods from a few years ago. They may sound better than white-van speakers, but I wouldn't bet on it.

Companies that're famous for making speakers, and nothing else, seldom sell crap like this. Even Cerwin-Vega's world-renowned Speakers For Drunk University Students are way, way better than true department-store crap. If the brand of your speakers can also be seen on televisions, microwave ovens and jaffle irons, though, watch out.

(Do not buy a telescope from a department store, either.)

Oh, and as a general rule, the more closely the front panel of a one-box "mini hi-fi system" resembles the cockpit of one of those tanks from Tron, the more dire will be the quality of the actual sound, which is largely limited by the quality of the speakers. (You can substantially upgrade cheap mini-systems by hooking up just about any old pair of full-sized garage-sale speakers in place of the standard ones.) It's perfectly possible to buy one-box "hi-fi" systems that really do have quite high fidelity in the first place, though. Look for wooden speaker cabinets, and minimal dekotora-ism.

Getting back, finally, to Dream Acoustics, their US site links to Dway Corporation, their distributor here in Australia. Curiously, though, the multi-speaker sets listed on the Dway site are all much more expensive than the eBay speakers. Different models seem to come and go rather frequently; at the moment 5-speaker sets start at $AU499, and you can pay as much as $AU1299 for the fanciest set. Plus delivery, which can easily add more than $100 extra, as I found after doing the old pretend-you're-buying-something dance to get the site to tell me what shipping would cost.

(The US site has prettier pictures, but no prices. If everything there had a price north of $1000, then it'd look exactly the same as the Web sites set up to fool people into thinking that various kinds of white-van speakers are actually high-end gear. Note, just to be clear, that I am specifically not suggesting that Dream Acoustics are actually associated with the white-van scam.)

Dream Acoustics aren't the only purveyors of suspiciously marvellously inexpensive loudspeakers on ebay.com and ebay.com.au, of course. I wouldn't be at all surprised if you can, by now, buy on eBay products from every Chinese factory that also supplies speakermen. It just took a while for someone to realise that all but the very worst white-van speakers actually are a product that can be honestly sold.

Most products at the centre of a scam, or of an exploitative multilevel-marketing deal that's not quite technically a scam, are essentially worthless. (Sometimes they're worse than worthless.)

But white-van speakers - the less-awful ones, anyway - aren't. EBay's low overheads probably do make it possible to make an honest living out of selling these things.

There is, let me be clear, a very large and very audible difference between the sound quality of even the very finest white-van loudspeaker and that of any "proper" speaker, of the sort that an actual hi-fi store would not be embarrassed to sell. (Or, for that matter, of the sort that you can build from a kit!)

But many white-van buyers are quite happy with their speakers, especially if said buyer is still wrapped up in a warm and fuzzy psychoacoustic blanket because they think they've gotten a huge bargain.

If you don't get slugged too hard for delivery, it becomes arguable that you can't go wrong in buying these sorts of speakers on eBay, provided you don't actually want particularly high fidelity. Here, for instance, is a page about Dream and some similarly-unnervingly-cheap eBay speakers, which do seem to be perfectly OK for the - very small amount of - money.

I, personally, would much rather get my movie audio through two good small speakers than through five lousy big ones. The Loudspeaker Kit's venerable build-'em-yourself M4 mini monitors, for instance, can now be had for $AU258 the pair, including delivery.

But I haven't actually listened to any of the eBay cheapies. If anybody reading this has, I invite you to tell us all what you think of them in the comments.

I'd also especially like to hear from any readers who have in fact bought speakers from a couple of blokes in a van.

I know you're out there.

Go on.

It'll be therapeutic.

Posted in Music, Scams. 20 Comments »

Squeak squeak SQUEAK! Tingle-ingle squeak!

25 May 2010 — dan

There are two silly-sounding musical instruments whose names I keep forgetting. With any luck, this post will fix them in my memory.

The first one makes a sort of tinkling "sproing" noise, and the second sounds like someone squeaking a cleaning cloth on a drinking glass, or window. They're both surprisingly common - considering how weird they sound by themselves - in Latin music.

This much information wasn't quite enough, however, for Google to lead me directly to the answers. (Not the first time, and not either of the later times when I forgot again, and looked them up again.) But I got there in the end.

The sproinger, frequently heard in the sort of 1970s cop-movie music that opens with frantic bongo drumming, is called a "Flexatone", or "Flex-a-tone" to give it its full original 1920s-patent trademarked name.

Flexatone

The Flexatone is as unlikely-looking a device as its sound (OGG audio sample) would suggest. It's essentially a percussion variant of the musical saw; the Wikipedia article explains how it's played.

A "genuine" Flex-A-Tone will set you back at least $US26.99 (or $US34.50, for the deluxe version!). But this eBay seller has, among a variety of other instruments that look absolutely ideal for giving to the small children of people whom you do not like, a "Flexitone" for only $US24.99 delivered within the USA, or $US33.99 including delivery to Australia.

Speaking as a man who already owns a siren whistle (not nearly as good as the expensive Acme version), a melodica and two Stylophones (the old analogue type, of course), I can't say I'm not tempted.

[UPDATE: I just noticed that a Flexatone is part of the striking apparatus of one of Tim Hunkin's ramshackle clocks! It's featured at the start of the quartz-watch episode of The Secret Life of Machines.]

And then there's that rubbing-glass-sounding drum.

Cuíca drum

It's called a Cuíca, and it actually is played by squeaking a cloth on something. There's a stick inside the little drum, anchored to the middle of its single head. You rub the stick with a damp cloth to play the instrument, and alter pitch by pressing on the outside of the head with your other hand.

Cuica stick

Here's a 4.6Mb video tutorial, which makes clear that certain jokes about the motions involved...

Cuica playing

...are far, far too easy to be worth making.

The Cuíca is also known as a "laughing gourd" or "laughing drum" (not to be confused with the various kinds of talking drum). That's a fairly straightforward name, which made the Cuíca easier to look up than the Flexatone. Many other novelty instruments also have names deducible from their sound, like the humble "slide whistle", here demonstrated...

...in Ben Cowden's inimitable "Wayward Calliope" (via).

Posted in Music, Toys. 11 Comments »

"...but some elves came and helped them, WHO WEREN'T EVEN IN THE BOOK..."

20 April 2010 — dan

Martin Pearson's The Unfinished Spelling Errors of Bolkien is very funny, very clever, and very hard to find.

[UPDATE: Martin says it's OK to download it for free!]


(MP3)

It's a two-hour, two-CD, filk-infested one-man comedy show about of The Lord of the Rings - both the book and the film versions.


(MP3)

Even if you don't usually like those The Fiftieth Time Some Dude Put Stuff About Elves And Cthulhu To The Tune Of "Jailhouse Rock" sorts of songs, I assure you that you are going to have a very hard time not finding Bolkien funny. C'mon, the guy actually sings the Black Speech inscription on the One Ring to the tune of "King of the Road".


(MP3)

The total length of the double CD, not counting six minutes of out-takes at the end, is about 115 minutes. And there are a lot of songs in it, but there's a lot of talking too.


(MP3)

The Bolkien CDs were recorded with a live audience, which is of course essential for this sort of thing. There are also not many of those annoying comedy-record moments when everybody laughs, but you don't know why, because it's a visual joke and you don't have video.

(There are a few videos of Pearson on YouTube, by the way.)

There are also only a couple of jokes that you won't get if you're not Australian.


(MP3)

Honestly, half of the world's English-speaking nerds should have a copy of this.

But they don't, on account of how it's not very easy to buy it.

Bolkien is listed here and there on podunk online CD stores (Pearson also has his own Web site, which is currently somewhat unfinished). The only online store I could find that even claims to have Bolkien available for sale, though, is Ducks Crossing, where the double CD costs a handsome $AU40 plus $AU6 delivery in Australia, or $AU12 to the USA. They do at least accept credit cards and currency-convert the total price, though, so US customers will pay a total of a mere $US48.36, delivered, for the double CD.

Which is, of course, a bit on the bleeding steep side.

Apparently you're also meant to be able to buy the CD through 7th Dimension Music. But for months now there's been nothing in that site's shop, and the product page for Bolkien has, for lo these many months, been a database error. Some of his previous stuff used to be on this site, too, but now it's broken as well. It's all very depressing.

So I e-mailed Mr Pearson (pearsonmartinXX@XXhotmail.com, without the XXs) and informed him of the large number of people who would like to give him money, if only the CDs were available at a reasonable price. I also asked whether he'd considered opening the money-tap rather wider by letting people pay for downloadable MP3s.

Martin said that if people want to buy the CD, they can e-mail him. And maybe mail him a cheque, so he can put it on a wooden table and take a picture of it, et cetera.

It struck me that buying CDs by e-mailing the artist personally is not necessarily a completely optimal e-business paradigm. I suggested he try out a sell-your-files service like (to pick a random, presumably-honest example) PayLoadz, or of course CD Baby, who sell physical CDs, and can also put artists' MP3s up on iTunes and Amazon and so on. (This is CD Baby's "Artist Sign Up" section.) But he didn't go for it.

So allow me to postulate a hypothetical situation.

Suppose, hypothetically, that someone were to illegally download The Unfinished Spelling Errors of Bolkien, from one of those intarweb bit-waterfall things that the kids are so enthusiastic about. Beats me how you'd find it, but perhaps some cunning search string featuring Martin's name, or just the word "Bolkien", might do it.

If that someone decided they liked it, they could go on to send a few bucks to Mr Pearson via PayPal. (Once again, that's pearsonmartinXX@XXhotmail.com, without the XXs.)

Martin doesn't have a PayPal account either, but I think he may be persuaded to get one if a thousand bucks pile up waiting for him.

UPDATE: Martin Pearson his own bad self showed up in the comments below, and officially gave free BitTorrent distribution of Bolkien his blessing.

So here's the torrent, people! Remember to PayPal Martin, pearsonmartin@hotmail.com, a buck or three if you like it!

(Alternative torrent link. This is the magnet URI.)

Posted in Humour, Music, Nerdery. 29 Comments »

The difference is as plain as the ear on your face!

6 July 2009 — dan

A reader just pointed me to this comparison of the recording quality of the Samson Zoom H4 Handy Digital Recorder, the Zoom H4n, and Sony's PCM-D50 portable audio recorders, on Brad Linder's blog.

These things are little high-quality digital audio recorders. They're smaller than most portable compact-cassette recorders - actually, they're approaching the size of an old microcassette dictation recorder - but they have sound quality that the old concert bootleggers could only dream of. These sorts of recorders come with built-in microphones, of far higher quality than the mics in any small portable recorder before low-power portable audio-processing hardware and low-cost Flash RAM made this sort of device possible. You could have put super-high-quality mics on an old cassette recorder if you wanted to, but it was pointless; nothing you could stick in even a large pocket could record good enough audio to justify expensive mics.

(Yes, I know there were some relatively small analogue-tape field recorders that gave very good results - usually because they recorded on something better than a cassette - if you plugged a quality mic into them. There was probably also some integrated-microphone doodad that recorded on small reel-to-reel tape or Type IV cassettes with Dolby S or something, about which I just haven't happened to hear. But modern digital field recorders are still amazing, all right?)

Anyway, Linder set up all three recorders next to each other, and talked and then played guitar into the built-in microphones. Then he posted the audio from the three recorders, for his readers to audition.

Overall, the commenters opined that the H4 was OK, the H4n was better, and the PCM-D50 was best. They were pretty much unanimous that the difference between the H4 and the Sony was as plain as day - compared with the Sony, the H4 was "muddy" or "muddled", "disjointed", "scrambled", or slightly noisier; one commenter called it "not even worth talking about". One guy even said he heard wow and flutter. There was general agreement that the Sony was clearly superior.

The only problem with all this - which another commenter soon discovered - was that Brad actually screwed up. Instead of pasting in the embed code for all three recorders, he pasted in the H4 code, then the H4n code... and then the H4 code again. He just labelled it as the Sony PCM-D50.

So the first, and the third, sound clips were precisely identical. On account of being the same sound clip twice. But the one that was labelled Samson Zoom H4 sounded lousy, and the one that was labelled Sony PCM-D50 sounded great.

Psychoacoustics: It ain't just a river in Egypt.

Wait. That didn't come out right.

This happy accident reminds me of the techniques James Randi has so often used on people with alleged supernatural abilities. I'm re-reading his classic Flim-Flam!, which contains a number of examples. When, for instance, a woman said she could use dowsing to find ancient ruins just by examining a map, without even a scale or North-pointer, Randi tested her on three maps in sequence, all of which were actually of the same well-explored part of Peru, but rotated and scaled differently.

Needless to say, her exceedingly vague results put "ruins" in different places every time, and not a one of 'em even managed to hit Machu Picchu, which was exactly the sort of thing she said she could find.

(Audiophiles usually seem to address psychoacoustic problems by adding as many more uncontrolled variables to their sound comparisons as they can. I presume this is some sort of demonstration that their perception of sound is not merely superhuman, but super-mega-ultra-hyper-human.)

Posted in Music, Science. 13 Comments »

Rockin' out over SCSI 1

20 April 2009 — dan

Via Hack a Day:

The creator couldn't get four ScanJet 3Cs at a reasonable price, so the scanner is overdubbed into four voices. But everything else is live - hence, presumably, the less-than-perfect sync between instruments.

Johnny Five is still totally headbanging at four minutes 11 seconds, though.

Posted in Hacks, Music, Nerdery. 2 Comments »

The quarter-size violins of the electronic-instrument world

14 March 2009 — dan

Everybody who found the SX-150 demo from that post to be agonising listening: The first of these videos is safe for you. The second is not.

This track's held together by the DS-10, of course, which is a proper little music production environment. Both the Stylophone and the SX-150 are sweetened up by a lot of reverb, as well.

But just the same - this is actual music, using the actual particular capabilities of these funny little synths. The SX-150 has My First Analogue Synth tweakability, and the Stylophone lets you do effortless "keyboard" glissandos, including only the "white notes" or - with some more dexterity - the whole chromatic scale.

Play these instruments "dry", though, and you get something more like this:

Still an actual tune, but not exactly easy listening.

Posted in Music, Nerdery, Toys. 6 Comments »
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