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In one of the most challenging reviews he’s ever undertaken, Martin Colloms tackles Linn’s new digital active loudspeaker system and it’s partnering streamer interface. Can it’s £50,000 total price be justified? Linn has developed considerable enthusiasm for a loss-free path for music recordings from what it terms the source. Here the source is not the music, nor is it the studio origination (about which the consumer can do nothing). Rather, Linn defines it as the point at which, until now, a theoretically lossless, digital audio signal becomes analogue, which is of course inevitable in order to experience sound. Linn’s classic viewpoint has long been that the music source available to the consumer must be protected and optimised. Readers may well recall its historical emphasis on the importance of optimising vinyl replay quality, rather than later stages of preor power amplification, Linn aiming to drive the rest of the chain with the best possible analogue source signal. An analogue source signal suffers from well known but normally also well controlled losses at every stage of the path to the loudspeakers. Each stage will contribute some degree of impairment, due to cables and connectors, grounding issues, some inherent noise, plus distortion and bandwidth limiting defects that are inherent in analogue stages, even though they can be rather small when considered stage by stage. When an analogue audio signal from a power amplifier arrives at a loudspeaker, the usual passive implementation then involves a high power filter network (the crossover) prior to the drive units. Configured to combine the acoustic outputs of the drivers in proper order, significant quality losses occur. Active Drive Although they’re common enough in professional circles, active domestic loudspeakers are quite rare. They use power amplifiers for each loudspeaker drive unit, and carry out the crossover filter function at pre-amp electronics level. This approach can provide great rewards in overall sound quality, especially in respect of more realistic dynamics. Linn’s expertise in active speakers goes right back to the three-way Isobarik loudspeaker, introduced nearly 40 years ago, which was available in both passive (DMS) and active (PMS) versions. (I recall a most enjoyable and impressive afternoon at Paul Messenger’s place, listening to his Naim-powered active Isobarik PMSs.) Since then, all Linn loudspeakers have been specifically designed to allow them to be converted to active operation. Digital Active More recently it has been possible to shorten the analogue system signal path by converting from digital at a later stage in a high quality DAC/preamp (eg a digital streamer), which includes a master volume control and sends its output via long cables to now active analogue loudspeakers. However, Linn’s increasing mastery of DSP (digital signal processing) has set the stage for the company to remove still more lossy analogue stages from the audio signal path, hence the new Klimax Exakt DSM streaming control unit. This drives digital audio directly to the new ‘digital’ loudspeakers with a high resolution feed in stereo (and eventually up to eight channels, for home theatre installations), via a custom made, very low jitter interface running on Cat5 cable. As in some studio and other previous designs, the designers’ intention is to postpone the conversion to analogue until the last possible moment, and Linn describes this conversion point as the source. This critical conversion is done at the individual inputs of an array of linear Class A/B power amplifiers, each connected directly to a drive unit voice-coil. Linn explains that traditional analogue losses through speaker or interconnect cables and active or passive analogue crossover components are therefore eliminated. Digital input, digital crossover loudspeakers, either for studio monitoring or for higher performance home and stage audio systems have been available elsewhere for some years, so what is it that makes Linn’s implementation special? The clock jitter figures for the interfaces are extremely low (just a few picoseconds), for which there is some correlation with sound quality, and the audio channels benefit from tight locking or synchronisation. I also see some value in the ambitious backwards compatibility program for this technology, which will allow some previously purchased Linn loudspeakers to benefit from the new digital expertise.
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