In this free video tutorial, Pro Tools Expert team member Julian Rodgers demonstrates a free alternative to using a dynamic EQ to tame harshness.
A standard de-esser is just a compressor with a filter in the side chain. When the filtered frequency is strong, it passes the filter, exceeds the threshold and compression occurs, but only when the particular undesirable frequencies occur. This compression is full bandwidth.
More sophisticated de-essers have filters in the side chain and only compress part of the signal when the threshold is exceeded. Some de-essers are very clever indeed offering extensive control. The Avid Channel Strip covers basic de-essing in the but the venerable Dynamics III De-esser has a useful extra feature over full band de-essing in that it has an HF only mode.
HF Only Mode
In HF Only mode the de-esser compresses from the frequency range set by the side chain filter upwards - effectively making an HF shelf dynamic EQ. While this can't compete with a genuine dynamic EQ with its bell-shaped bands of dynamic EQ, it is much better than full band de-essing in this application.
The electric guitar is particularly suitable for this technique as it doesn't contain a great deal of important HF information above the high midrange. In an application like dealing with a ring on a snare drum in the overheads, this technique would be less successful because the HF shelf would pump the cymbals in an unacceptable way.
So in spite of its limitations, this technique can be useful on the right source material, and at present Pro Tools doesn't ship with a dynamic EQ.
What About Multiband Compression?
If you have the Avid Pro Series plug-ins you have a better solution available in the form of the Avid Pro Multiband Dynamics. the line between a dynamic EQ and a multiband compressor is sometimes blurry and this powerful plug-in is more than capable of taming harshness.
Watch the free video to see this in action