Metal Detectors

If it's transparent loudspeakers you crave, David Price implores you to seek out Usher’s new Be-10!

Much to my chagrin, the only science I wasn’t terribly good at was Physics - not a great admission for an electronics obsessed, internal combustion engine-fascinated fifteen year old. But then, a curious ability at Chemistry kind of made up for it. I’d never been particularly excited at the prospect of test tubes, Bunsen burners and fume cupboards (although the occasional opportunity to add water to acid was never missed), but somehow almost by accident, I took to it like a duck to water...

One of the reasons was learning about the Periodic Table. “Wow,” I mused, “here’s everything you need to know, all the chemical building blocks mapped out in front of you - learn that and I’ve cracked it”. Thus began my slavish, by rote, chanting of “H-He-Li-Be-B-C-N-O-F-Ne-Na-Mg-Al-Si-P-S-Cl-Ar-K-Ca”. Although it wasn’t quite as easy as “Every Good Boy Deserves Football” for my Music ‘O Level’, the mnemonic eventually sunk in and lo and behold, Chemistry GCE was a pushover!

Well, a decade or so (ahem!) later, my increasingly porous grey matter has retained little of my school science exploits, but one thing it does remember is the Periodic Table, and my interest in materials technology remains. That’s why I’m still fascinated at the way loudspeaker designs choose different substances to make drive units - from plastic film membranes for electrostatics to slivers of metal for ribbons, or any number of variations of doped paper and plastic with conventional moving coil cone drivers. The fun thing is that there are no rules - aside from that the thing or bit that moves the air should be as light and rigid and unresonant as possible...

Oh, and I forgot the final dictate - with commercially available speakers at least - cost. Let’s not forget that there’s got to be a point in making them in the first place (i.e. the company’s continued existence), so financial considerations hold sway. That’s why most speakers use moving coil drivers (they’re the cheapest and/or the easiest to source or make), and also why most moving coil drivers use plastic cones of one type or another. Again, the same sort of thing you make Coke bottles out of or dispense Shampoo from is never going to break the bank now, is it?

Still - before we get too ‘knowing’ and cynical about why the commercial reality of production loudspeakers is generally so far away from the theoretical ideal - let’s not forget that this is only half the story. Just because you’ve got the best drive unit material doesn’t guarantee you will have the best sound - you need to integrate those drivers with the cabinet and other drivers successfully before you even come close. However, what you can be sure about is that if you haven’t got the best driver materials, you’ll never be able to get the best sound.

And so to the Usher Be-10 - which makes a very earnest attempt to achieve the state of the loudspeaker art by using not polypropylene or paper, but Beryllium for its treble and midrange units. My ‘O Level’ Chemistry textbook reminds me that this is the lightest stable metal on the planet, and only the fourth heaviest element in existence. The prospect of using Hydrogen or Helium to make your speaker cones is - shall we say - ‘airy fairy’, and I wouldn’t want to sit too close to a Lithium tweeter unless it was sitting in a bath of oil - to prevent it spontaneously combusting like a Spinal Tap drummer! In short then, ‘Be’ is ultra light yet stable, and as such ideal for use in a transducer. Because of its very nature, it is far better suited to the job of moving air than anything made from heavy old Magnesium or Aluminium. Well, Beryllium would be ideal, were it not for the fact that it’s so expensive to produce safely - for consumer loudspeaker applications, the price certainly isn’t right.

This explains why so few speakers have ever employed this material - with the standout exception being Yamaha’s NS1000M which I use to this day. Sure, they have their weaknesses, but the speed, clarity and insight is like no other I’ve heard. The Yamahas’ strength comes not from using a Beryllium tweeter, but from mating one to a five inch Beryllium midrange dome so well. With this speaker, you have all the most audible frequencies handled by phase-coherent, identical sounding transducers, and the results are startling. Well, to this select group you can now add the Usher Be-10s - for they too run Beryllium tweeters and midrange units, although with the Be-10 Usher have chosen to invert the midrange dome to a cone profile. This, says the company, is the first ever such driver.

£10,500 buys you a very big (365x715x1215mm) box weighing no less than 92kg (including its base). The Be-10 is, like so many of my favourite loudspeakers, a big three way running a 1.25” Beryllium tweeter from 40kHz down to 3.46kHz, after which that 5” inverted Beryllium dome takes over. This goes down to 550Hz, when an 11” Eton woofer handles everything right down to 25Hz (claimed) with the help of bass reflex loading. One problem for the bass unit to contend with, with two of the world’s fastest, lightest drivers pulsing away above it, is how to keep up. For this reason, Usher have chosen Kevlar - which is another light and stiff material (a patented para-aramid synthetic fibre) - famous for being used in bulletproof jackets, amongst other things, due to it being five times stronger than steel on a weight-for-weight basis. The cabinet is a familiar profile for Usher, being rounded at the back (to reduce resonances) and angled backwards (to provide time-alignment). Needless to say it is massively braced and the standard of finish is - as you’d expect from high end Ushers -

immaculate.