A Short Guide To

Mastering & Manufacture

Introduction

This page is designed as a brief guide to the processes involved in turning your studio master into saleable CDs, and cassette. It is impossible to cover every aspect in depth, but we hope that this information will help you make informed decisions and to avoid costly mistakes. We have made every effort to ensure that the information is accurate, but technology and processes are changing rapidly. If you are unclear about anything please do ask.

After the studio

Once you have been in the studio and spent time, energy, effort, and possibly a considerable amount of money committing your project to tape (or disk), you probably want to have it duplicated either for sale to the public or for distribution to record companies, etc. in order to secure a deal. Hopefully the studio will have done a good job for you, and you will be pleased with your master. There are now various process which your material will need to pass through in order to be manufactured.

Initially these are the same for cassette, CD but they then diverge and there is a separate section for each of these.

The diagram below should illustrate this (stages in blue are optional):

Mastering & Pre-Mastering

The master which you have recorded and mixed at the studio is normally known as an ‘Original Master’. It will normally be on either a Digital Audio Tape (DAT), which should ideally be recorded with a sampling frequency of 44.1 kHz, with start identification marks (Start IDs) and absolute time (A Time) or Timecode, or as audio files (such as .wav, AIFF, etc). Many studios will get your material in the right order, but it is often then necessary to make adjustments in order to create a Production Master which can be sent to a factory for manufacture. This involves pre-mastering and may also include mastering:

• Mastering (sometimes called Pro-Mastering) - affects the audio in some way (eg. level, eq, compression, etc.).
• Track spacing - the gaps between songs affects the pace of a production. There are no hard rules, and often they are set by feel.
• Fades - fading out (and sometimes in) is normally done during mixing, but many analogue mixing desks produce ‘lop-sided’, uneven or crackly fades, and many budget digital desks introduce noise and distortion at the bottom of the fade. If you intend having your project edited or mastered, consider doing the fades at this stage as they are usually much better quality.
• Relative track volumes - very often songs are mixed and recorded at maximum level on the original master. It is then necessary to set the relative levels of songs to get the right feel.
• Corrective equalisation - this can be used to compensate for imbalances in the studio monitors/engineers hearing (!) when the songs were mixed. Common problems are too much or too little bass caused by mixing on small speakers (eg. NS10s), and harshness caused by adding too much upper mid because the monitors were dull.

Creative processing including equalisation compression and multi-band dynamics can dramatically increase the impact of a production by adding extra energy and allowing a higher average level. There is often an improved sense of space. Experience has shown that having a new and fresh pair of ears at the end of a project can yield an improvement of between 5 and 50%! It’s definitely worth considering.

Pre-Mastering - preparing and creating production masters.

Material is checked for technical faults (overloads, distortion, clicks, drop-outs, etc.) and then a Production Master is created which is suitable for the format required:

• Cassette production master: your material is transferred from the original source master (or previously mastered material) onto our edit system. The material is divided into two which represent the two sides of the cassette. Ideally Side 1 is normally set to be longer than Side 2. The maximum level is noted and 'line-up' tones are added before the programme starts in-order to ensure that the duplication plant can set their equipment to get optimum results for your material. The material is then played out as a production master (either a DAT or audio CDR), played and monitored for errors and drop-outs.
• CD production master: your material is PQ coded and then transferred onto one of four formats; DDPi files on a DVD-R, DDP Exabyte, 1610/1630, or CDR.
  • DDPi is the newest format. Disk Description Protocol files are generated and then burnt, together with Check Sum data, to a DVD-R and verified. Together with DDP Exabyte, this is the most reliable format and all data can be fully verified to ensure no errors creep in.
  • DDP Exabyte is a very secure high speed computer data tape system which has been in use for many years by banks, etc. It too can be fully verified to ensure no errors creep in. It is becoming less come now as it is slower to use.
  • 1610/1630 was the original format used for CD production. Digital audio is recorded via the Sony 1610 or 1630 processor onto a UMatic video tape. The data on the tape can be verified, but the tape is expensive, bulky and delicate. This system has almost been phased out, but we retain the ability to make new masters and transfer existing ones.
  • Compact Disc Recordable (CDR). CDRs are ‘burnt’ with a special laser which heats up a layer under the surface of the disc, leaving a pattern of dots. There are several potential problems with CDR:
    • firstly many systems do not accurately transfer the data,
    • secondly any dust and contamination on the surface of the disc or airborne particles in the writer can prevent the laser from burning the correct pattern onto the disc (this can affect the sound of the CDs and may even mean some discs are unplayable),
    • thirdly most CDR systems cannot check the data which has been transferred, so you may not realise there is a problem until it is too late.

The Digital Audio Company uses either DDPi files on DVD-R or DDP Exabyte for CD production masters because it is very secure (we have never had a master fail!). We have run extensive listening and data tests, comparing original source material with production CDs to check that what the client supplies is what the final CDs sound like. We have never found any evidence of changes in sound when DDP is used.

Quality control is very important during CD pre-mastering. All CD masters are fully auditioned for audible problems either as they are loaded onto the edit system or played out. Our DAT machines have error indicators and the edit system analyses the digital audio for errors. As the master is being written it is automatically checked for data errors which are corrected. Once the master is written it is then verified (double checked) and for Exabytes and 1610 masters a report is printed to guarantee the quality. PQ coding is the process which adds extra information to the CD which tells the CD player where each song starts and stops, and its duration.

A CD can have up to 99 tracks and each track can contain up to 99 index points (although not all CD players can access indices).

It is also possible to embed a Bar Code number and International Standard Recording Codes (ISRC) into the table of contents on an audio CD to identify the owner of each track. ISRC's consist of a series of letters and numbers which are allocated by the PPL in the UK, and regulated worldwide by the IFPI. ISRCs can be used by radio stations, etc., to automatically log play out of your material for royalty payments. Visit their web site or for more contact information see our links page.

CD text is a relatively new addition to the CD specification and we can include information such as track title, composer, arranger and artiste when creating a DDPi master. Please ensure that you supply all CD text information with the correct spelling.