Meridian splits HDMI sound and vision for better quality

HD audio and video don't mix - at least not on HDMI connections. That's the thinking behind the new HD621 switcher from Meridian, which is designed to extract the HD audio from an HDMI hook-up and transmit it to the company's AV components.

The HD621, which sells for £1495, is a six-way HDMI switcher, allowing multiple sources to be fed to a single output to a TV, monitor or projector. It's controlled by other Meridian equipment via the company's comms link, but as well as providing convenience it also separates out high-definition audio from the video.

The audio can then be fed to suitable Meridian surround processors via the proprietary  Meridian Multichannel High Resolution connection. This is able to carry eight channels of balanced digital audio at up to 96kHz over a cable terminated with RJ45 plugs.

HD over HDMI not ideal
Meridian explains that transmitting HD audio and video over HDMI is hardly an ideal solution: "...audio travels down an HDMI cable in bursts, and this can significantly increase the level of jitter in the signal. Digital video signals have traditionally been the bane of those in search of the best audio quality. They include very high frequency signals with very fast rise-times and thus tend to radiate an enormous spectrum of harmonics.

"Ideally, therefore, it makes sense to separate audio and video signals, in particular minimising opportunities for audio quality to be degraded by the presence of video.

Up- and down-sampling
"The HD621 performs up- and down-sampling of digital audio to ensure the very best sound quality from today's varied sources. Meanwhile, Meridian's highest-performance FIFO [First In First Out] buffering technology removes jitter, consistently delivering a significant improvement in sound quality from all HDMI sources.

"The HD621 integrates HDMI sources seamlessly into your Meridian system; so seamlessly, in fact, there's even a programmable lip-sync delay to be sure sound and picture remain in perfect synchronisation – one of the most important details in a quality video experience."

The HD621 is available now, in both rack-mount and freestanding versions.

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