Mastering

Mastering is about two things. Firstly it’s about careful listening by an experienced engineer, on a reference-quality reproduction system in a familiar, acoustically controlled environment. In that way, decisions on sound quality, and any changes felt necessary, may be made with utmost confidence.

Secondly, mastering is about preparing the pre-master to be used for replication or duplication. As well as the audio, this pre-master carries information such as the track start/finish information and barcode. This pre-master needs to be prepared in the way expected by the manufacturing plant, and should be free of faults which would cause problems, which at that stage can be very costly.

After listening to a recording in controlled conditions, it may be decided that it would benefit from some EQ (‘equalisation’) to alter the tonal balance, some extra reverberation, or some other process. In addition, it is often possible to remedy some minor blemishes using Cedar Retouch, resulting in a more polished sounding recording. Lastly there is also the issue of levels. It’s important that the master is made at an appropriate level, which for digital audio (like CD) means that it should peak just below the maximum possible (0dBFS). More obvious to the listener is the average level, which depends on the dynamic range of the music. In many cases it’s best to leave the listener to enjoy the full dynamic range in a natural way. There are times, however, when an excessively low average level needs to be raised, which means that the dynamic range must be controlled. Whether this is achieved manually (‘over-controlling’) or automatically (compression) will depend on the dynamic nature of the recording, and the subjective effects of these processes. When done subtly and sympathetically, very few need be aware of an ‘invisible hand’ exerting some control over levels.

The position of track markers is contained in the ‘PQ’ subcode, and this information is added at the mastering stage, along with a barcode and the International Standard Recording Code (ISRC) for each track, where appropriate. See here for more details on ISRCs: http://www.ifpi.org/isrc/

Recordings of a higher resolution than the release format (which for CD is 44.1kHz/16-bit) are processed at the mastering stage, with noise-shaped dither applied following re-quantisation for optimum performance.

We can prepare pre-masters in several ways, the most common of which are pre-master compact disc (PMCD) or DDP on 8mm Exabyte tape. We can also supply the supporting paperwork of PQ lists and verification where appropriate. PMCDs are burnt at low speed on our extremely reliable Plextor writers, using high quality branded stock. This combination has a proven track record of very high reliability and widespread compatibility.