Meridian America Meridian 518 Dynamic-rangeoptimisation with Gain, Dynamic-rangeoptimisation with Pre-emphasis

Appendix 4 –Resolution Enhancement 51

Figure 3. Showing the audibility of noise in the LP system for comparison with digital channels.

Dynamic-range optimisation with Gain

The noise-floor of a digital system is determined absolutely by the lowest preceding wordsize. For nearly all commercial material this is 16 bits.

518 allows you to get the best out of whatever comes next, by making sure that the full output capability is used. Gain can be used in Resolution Enhancement and Mastering to boost the level of the signal to fill the available capacity.

For some reason, many CDs are recorded well below maximum level. By boosting these we are able to reduce the audible effect of noise in subsequent processing, or digital filters in DACs, or in the analogue electronics.

Getting this right is easy – 518 immediately tells you if had to 'clip' the output because you asked for too much. See page 18.

Dynamic-range optimisation with Pre-emphasis

Real-world music and speech signals do not have equal energy at all frequencies. Typically the loudest sounds happen in the mid-range and peak levels are much reduced above 5kHz.

This fact has been exploited extensively in audio systems over the years, with a system known as pre-emphasis.

Input Pre-emphasis Channel De-emphasis

Using Pre-emphasis and de-emphasis to improve channel performance

The diagram above shows the general pre-emphasis method. To take best advantage of the channel – which could be an AM or FM radio link, an LP record, a tape recording, a CD or a DAC – high-frequency signals

518 User Guide