I sometimes hear a very low level crackling noise (sounds similar to dithering) around signals that are fading into or out of the consoles noise floor. What could be causing this?
You are probably hearing the D8Bs noise shaping filter. This fixed-level filter is on each channel and designed to cut console noise and render channels completely silent when no signal is present. When the filter threshold is triggered and the filter opens, the consoles noise floor becomes present for that channel. As the level of this noise is extremely low, the vast majority of audio material will be high above the noise floor so the noise floor will not be audible. When there is a very dynamic signal present and the output signal of the console is amplified with a large amount of gain, the noise can occasionally become audible. This noise shaping filter is a standard feature of the console. It is designed to give the console extremely quiet performance and is very useful when recording high amplitude, dynamic signals. Using proper gain structure to achieve maximum gain from the mic pre into the A/D converter can minimize the effects of the noise shaping filter. V3.0 (or higher) off
