TECHNOLOGIES

In this section you can learn more about the technologies Sound Temple use. For ease of navigation this guide has been split into multiple pages and you can jump to a topic that interests you by clicking the links below.

• Introduction
• Electronic Signal Generation
• Digital Audio Signal Generation
• Sample Rate
• Bit Depth
• Digital and Analogue Audio Signal Manipulation
• Digital Audio Mastering
• Clip Removal
• Volume Control
• Panning
• Normalisation
• Compression
• Limiting
• Expansion
• Noise Gates

Digital Audio Mastering

Traditionally, audio mastering involves the use of high cost analogue equipment. Digital audio mastering involves high level processing of digital data to produce a final data file that is of optimum digital quality. This is necessary for compact disc, tape or vinyl record manufacture. There are industry standard processing functions that are essential for professional mastering results. Digital mastering processes needs to be performed in a specific order. The order is important as it prevents deterioration of the signal. An agreed order for mastering is De-clipping, DC offset removal, normalisation, stereo re-alignment and compression. Each of these processes will be explained in the following text.

Clip Removal

Recording of a digital signal requires precise line control. In order to achieve the best analogue to digital conversion possible, recording levels need to be as high as possible.

Clipping is the saturation of a digital register. Using a 16-bit register as an example, clipping occurs when the analogue voltage maps to a value of 32768 or - 32767. If a recording is 6db below clipping only 15 bits out of a possible 16 are being used. This results in only 32768 voltages being mapped compared to 65535 voltages when a full 16-bit compliment is used. Often, a digital recording is perfect but for a few samples exceeding the 16-bit size. Using a wave editor the clipped 'peaks' can be re-drawn. A clip removal function simply does this automatically, by bringing the peak level back into range. This is however only suitable for a few samples. Any more than approximateley one second and the signal quality is impaired.

Volume Control

Volume control, or more correctly gain, is the process by which the amplitude of the wave is increased or decreased by a constant value. Variation of volume over a constant time causes volume 'swells' or 'wah- wah' type effect. Volume control for mastering is essential. Compact discs are mastrered at -0.3db. Too low a volume and the listener would have to raise the volume on their amplifier. This would increase the signal to noise level and reduce quality.