Griffin pitches out-loud music without wires - or speakers
iPhone dock and stereo that doesn't have a speaker or power source
Griffin has created an iPhone docking station that’ll have Alexander Graham Bell and Thomas Edison rotating in their graves, because it plays music without speakers and doesn’t require electricity.
Griffin's AirCurve: no speaker, no batteries, but - somehow - sound
The translucent polycarbonate AirCurve is described as a “breakthrough acoustic amplifier dock”. It works by collecting and amplifying sound from the iPhone’s own speaker, and then blasting it out across a room with a quality that Griffin claimed is akin to a pair of desktop speakers.
A “coiled waveguide” also does away with the need for any power source.
Concerned the output might be a little on the light side? Griffin reckons the AirCurve’s sound amplification is sufficient to get you up in the morning. It's touting the iPhone and accessory as a combo alarm clock.
One drawback: if you want to charge your iPhone when it’s docked, then you’ll have to connect an additional Griffin Dock Connector Cable – which is sold separately.
The Griffin AirCurve is available now online for $20 (£9/€12).
"So that would be what most people would recognise as a "horn" then - you know, like those trumpet shaped speakers used at outdoor event for the PA. All they've done is coil one up and make it look pretty."
It's more like a folded horn. Straight horn flares usually have a compression driver fitted to them whereas a folded horn will have a regular driver in them.
The thing nobody ever told me about exponential horns was, whether it was the radius or the cross-sectional area that was supposed to vary exponentially with distance .....
Yes it's just impedance matching. No it doesn't use resonance as resonance only boots narrow frequency ranges and that would sound horrible.
However even though this does not actually amplify anything, it causes the power output of the loudspeakers to rise.
Essentially it's like this:
Air is fairly simple to move under normal circumstances, however the membrane is much harder to move than the surrounding air. So the loudspeaker puts most of it's force into moving the membrane. It could push or pull a lot harder. Now the horn makes the air appear more stiff on one side and distributes that force to a larger area.
I once did some work on horn loudspeaker design...
The major problem with horns is that the lowest frequency 3db point is a function of the area of the horn mouth and the length. It is 40 years since I did the calculations, but I seem to remember that to get down to 20Hz (the recognised limit of human hearing) you needed a horn 40 feet long and 20 feet in diameter at the mouth.
A little plastic box won't hack it for bass notes.
"akin to a pair of desktop speakers."
i.e. the cheap passive ones costing around a fiver and sounding bleedin' awful. Fair enough for the job in question, I suppose, but another nail in the coffin of audio quality delivered curtesy of the portable digital music player.