Shout about quiet power
12 October 2009
I spoke at length last week to a British company who believes it can turn the mobile music market upside down.
This is not a claim that it has invented the successor to the current phone/MP3/MP4/camera combo. It is instead is the obvious compliment to them – the portable speaker. The barrier to doing this successfully in the past has been power management.
There reached a point many years ago, when music systems shrunk to the point where it seemed inconceivable that quality could be maintained. I remember the wonderment of replacing my old ‘music centre’, admittedly at the sacrifice of the turntable, for something a quarter of the size and comparatively scaled-down speakers, and finding music quality had actually improved. I know there is now a body of opinion that believes that ‘depth’ of the sound through vinyl has never been successfully recreated in digital forms, and the old LP has made a minor, but probably permanent, comeback. However, like most people, my listening tastes are not so sophisticated, and the ability to store a room full of vinyl on my iPod far outweighs any perceived loss in quality. My music collection even stays in alphabetical order, despite other people tampering with it!
I am straying from the point. Even my new ‘midi system’ in the 80s or more recently, my iPod Dock, still need to be plugged in. Battery-powered speakers are too power hungry to last for a meaningful amount of time.
Now we have a technology from this British company, called Audium Semiconductor, that could change all that. It is one of those clever ideas that sets the imagination going, not least because I can imagine buying a products based on this technology myself. What Audium did was to analyse the power usage of speakers. In some ways this is obvious if you want to make something better – you start by analysing what needs to be improved. Class D audio amplifiers though are claimed to already be in the region of 80 to 90% efficient – so getting another 5% or 10% does not sound like it is going to extend battery life by a meaningful amount.
However, Class D amplifiers, although known for their efficiency, are only that efficient at peak power. Audium looked at the power usage across the spectrum of listening volumes and noticed that the power required by the amplifier was almost the same (within 10%) at zero volume as it was for ear-shattering maximum volumes. So when ears are being shattered, there is the comfort of knowing that your audio equipment is running very efficiently.
Most people don’t want their ears shattered though, and efficiency tumbles as the volume decreases – the input effectively staying the same for decreased output. Audium’s new chip has been designed to rectify this, having minimal quiescent input power which rises approximately in proportion to the output. The trick apparently comes from an innovative architecture and modulation scheme. At peak output there is little difference in efficiency between Audium’s new amplifier and the Class D, but at the sort of volume that most people listen to most of their music at – about the volume of a loud conversation – Audium claims that it’s amplifier requires only 5% of the input power. At the sort of volumes I would like my children to listen to their music at, this reduces even further to 2%.
This now moves the new chip (the AS1001) into the realms of a disruptive technology – something that can really alter the possibilities for portable music. Four C batteries, claims Audium, can power speakers for ten months based on a full three hours of listening every day. Not only does this open the door to viable ‘active speakers’, it could also make a massive dent in the 660 million batteries that the UK uses every year.
First products using the chip are expected in Q1 2010, so not quite in time for my Christmas list!
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