Project radio has been quiet for some months due to higher priorities and consulting workload.
There are several projects waiting to attention though, with Bang and Olufsen’s Beolits top of the list. The new BeoLit 12 box designed by Cecilie Manz caught my eye but it’s a far cry from Jacob Jensen’s innovative design from the early seventies. Instead of radio the 12 is called a ‘portable music system’, I’m thinking that’s very similar to a transistor radio as it’s portable and contains components that work systematically. Instead of analogue input the BeoLit 12 accepts digital media sources. Terrestrial channels and stations replaced by metadata filters selecting streaming internet radio from anonymous servers in the cloud.
Technology changes with ever more complexity to source data. One maker recently combined the two ends of the spectrum (pardon the pun) and grafted a bluetooth receiver to a seventies Beolit radio to give BeoLit 12 functionality to a Beolit 600. Wonder what it sounded like? Well that set me thinking about upcycling a few of my old Beolits that are sitting broken and unloved. So check back in a couple of months to see what morphs.
Sound quality of portable devices often falls short and I’m looking at ways to improve the audio experience. Lack of bass frequencies and muddy raspy vocals annoys the most. Roberts classic analogue revival series was a major disappointment when I first switched one on. It looked good, echoing the original 50s design. The R250 has a solid wooden case with a cheap looking 75mm diameter 8Ω speaker that has a small permanent magnet. I’m guessing the speaker’s unit cost is less than 50p in the bulk that Roberts buy and this untimately determines the tone and timbre heard. So it’s no surprise that replacing the standard speaker with a better driver improves sound quality. But it’s not quite so easy. Magnet size is not a good measure of quality – size is not everything! The example below shows a larger more powerful driver than the usual one and it sounds worse!
So why is this? I suspect the speaker cone flexibility – or rather the surround – plays an important role in frequency response and intermodulation distortion or just plain old harmonic distortion. There are ‘full range’ drivers available for less than £7 that sound much smoother with far more clarity – see Roberts R250 Speaker Upgrade. They too have larger magnets but also wider foam surrounds that flex better than crimped paper on the cheaper units. Bass is still not great – the 65-70 cm diameter surface area can’t pump enough air I suspect. Displacement of air – piston action – well bigger diameter pushes more air. Just make sure the driver’s depth does not exceed 38-40cm as it won’t fit inside without touching the circuit board.
Audio for the speaker comes from a small 8-pin device that can deliver nearly one watt of ‘music power’. There’s another marketing phrase that misleads the customer. Speaker sensitivity is important to ensure the replacement is loud enough.
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