While system flexibility and adaptation is central to recording, the ‘Chapel’ control room provides an acoustically neutral and consistent monitoring environment for mixing and mastering. A high quality, linear critical listening system is essential for this process, and for me, this is provided by active loudspeakers from ATC. SCM100 speakers are used for Left, Centre, Right, while movable SCM50 and SCM20 speakers are used for surrounds. An SCM0.1/15 is also available when Low Frequency Effects are needed. This system therefore adapts readily to stereo, 5.1 or 7.1 formats, as required.

It is worth noting that my immersive mixes, while referencing balances used for final stereo output, are new mixes derived from discrete multi-channel recordings of the original capture space, and are not ‘up-mixes’. The difference here is that I am seeking to make recordings with more authentic and realistic spatial rendering, not simply adding digital effects to bounce sound around the listening room.

Processing is provided by DXD-capable (352.8kHz/ 24bit) plug-ins as well as a small assortment of quality analogue units from Focusrite (ISA115 EQ & ISA131 dynamics), DeMaria Labs (ADL1500), Teletronix (LA2A), Amek (CIB) and Peach (stereo tube preamp/compressor).

For mastering, the complete suite of CD/SACD creation tools and Final Check Metering available within Pyramix provide comprehensive control for final optimisation and output. Multiple file sets can be generated including all common digital release formats from mp3 through to DSD256, as well as pmi and DDP images for CD replication. All immersive formats are supported as well as Ambisonics.

A brief look at why high resolution and multichannel recording are worth bothering about

The human brain detects and uses inter-aural time differences as short as 10 μ sec (and some would argue 5 μ sec) to build a model of the sonic world around us and give us information about the placement and distance of sound sources within it – an ability humans have depended upon over the ages for survival. 5 micro seconds equates to 1/200,000 of a second or 200kHz as a sample rate. Taking note of the Nyquist criterion, this means that for a digital recording to render this timing detail undistorted, the sample rate would need to be 400kHz. And so this is the sample rate that may be required for our digital recordings to approach being indistinguishable to us from the sound of the original performance.

The illustration on the right shows how digital recording deals with a 3 μ sec impulse, and how increasing the sample rate enables much closer rendering of transients in the analogue world.

Not shown here is DXD, which has a sample rate of 352.8kHz and so rivals DSD, and is also getting pretty close to our 400kHz target.

This is a single channel frequency analysis of a recorder and string quartet mix (Alicia Crossley & the Acacia Quartet – ‘Muse’ album) from a DXD recording showing high frequency musical energy extending well beyond 100kHz, albeit at relatively low levels. While we may not hear these frequencies directly, the sound, even on small speakers at relatively low level, has a beautiful overall silkiness that is unmistakable.

Increasing the number of playback channels beyond the standard pair for stereo, in combination with this higher resolution results in a much more engaging and compelling musical experience than usual for a recording; one that’s much closer to what we hear in a live performance.