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Stereo-to-5.1 Upmix Processor & SMP200 Mic Preamp 'Sneak-previewed' at IBC

Wakefield, UK, September 2008: Surround and stereo microphone manufacturer SoundField previewed two new products at IBC 2008, both aimed at the broadcast market. The first, the UPM-1, is a complete departure for SoundField: it's a hardware stereo-to-5.1 upmix processor, designed for HD broadcasters who use a lot of archive stereo material and wish to generate acceptable 5.1 broadcast mixes from stereo soundtracks.

"Most of the material broadcast by music entertainment channels, classic movie channels and sports broadcasters is of course in stereo — pretty much anything that dates from before three or four years ago," explains Ken Giles, Managing Director of SoundField. "Multi-channel recordings are hardly ever available to properly remix this material into 5.1, to say nothing of the budget and time to do so. So most broadcasters are using the original stereo, which is very disconcerting for HD viewers, as the audio keeps switching to 5.1 for recent footage and then collapsing back into stereo for older material."

Of course, software and hardware upmixing tools have existed for some years, but most of them create material for the extra three channels in a 5.1 mix by using processing, for example adding reverb or applying phase-shifts to the stereo material to create information for the rear surround channels. Instead, the UPM-1 generates the material for the extra channels by closely analysing the source stereo signal over time. Using a unique algorithm developed for the purpose, SoundField's processor can detect reverberant content in the stereo signal, differentiate it from the direct sounds in the mix, and separate it out.

"A stereo mix might only be two channels," explains SoundField's Chief Designer Pieter Schillebeeckx. "but it contains a great deal of spatial information which, if analysed correctly, can be used to create a six-channel surround mix. The UPM-1 can detect the distinctive repeated patterns and phase-shifts in the frequency content of reverberant content, and distinguish it from the more directly recorded audio in the mix. The result is a 5.1 mix that sounds much more like the original recording. Also, because the processing is based on analysis of the original stereo, the output is programme-dependent, and will change depending on the nature of the input.

As with SoundField's surround microphone systems, users can adjust the details of the processing directly from the UPM-1's front panel, with control offered over a variety of different parameters including the level of the direct and ambient components in the front and rear channels, and the divergence of the Centre channel in the generated 5.1 mix, with options from a discrete Centre channel at one extreme to a phantom Centre at the other. Output level controls are also offered for each of the channels in the final 5.1 mix. The UPM-1 will retail for £2475 excluding VAT in the UK, and is planned for release in early 2009.

The other product previewed by SoundField at the show, the SMP200, is a four-channel mic preamp, designed to complement SoundField's recently launched SPS200 software-controlled microphone. The four-capsule SPS200 is SoundField's most affordable product, and achieves this by offering software-based decoding and processing, rather than shipping with a hardware processor and control unit like all the other products in the SoundField range. For preamplification purposes, the SPS200 can be used with any multi-channel mic pre or digital interface with onboard preamps — those on the MOTU Traveler or Prism’s Orpheus are ideal. However, the output of the SPS200’s four capsules still needs to be gain-matched, and the SMP200 is designed as a one-box dedicated solution to address this need. Capable of being used as a standard high-quality four-channel mic pre, the SMP200 differs from other multi-channel preamps by offering a ganged master gain control, 48V phantom power and a low-pass filter that can be applied simultaneously across all four channels, thus ensuring the outputs from the SPS200's capsules remain matched.

"If you already have four mic preamps, you can of course use those with the SPS200," explains Ken Giles, Managing Director of SoundField. "But customers interested in the SPS200 kept asking us if we could provide them with a dedicated one-box solution."

The SMP200 will retail for £875 excluding VAT in the UK, and, like the UPM-1, is scheduled to begin shipping early in the New Year.