This step is an additional and optional step based on personal preferences that is reasonably effective in reducing some unwanted noise. Records containing loud and distorted passages may benefit from selected dynamic compression which aims to reduce some of the high frequency "rattling" that accompanies groove wear and tear.

This step should be done after trying to resolve the problem using the various impulse noise filters thru selective filtering and amplitude reduction. The aim is to stabilise the noise-sound pattern for the continuous noise filter (CNF) whilst trying to retain the original fidelity as best as possible. The aim is to reduce the amplitude of loud distorted passages and/or reduce the high frequency amplitude in loud passages that may otherwise escape the CNF and promote unwanted digital artifacts.

The settings vary depending on the fidelity of the original content. For example, acoustical recordings will benefit from a lower filter frequency of ~2500-3000Hz whilst later electrical recordings will sound best if the dynamics compressor operates around 3500-4000Hz or higher depending on the nature of the unwanted noise being suppressed. Similarly, the detection threshold will depend on the amplitude of the recorded content and overall dynamic range. In the end, the effect is overall best if there is a 3-6dB reduction in high frequency noise around loud passages or up to 12dB for distorted/damaged passages. In DC 7 onward you can use either the "Punch & Crunch" multi-band dynamics processor, or the original simple dynamics processor tool as shown below:

For extremely distorted sections of a recording, use the dynamics processor tool more aggressively on selected areas as you would the impulse noise filter.