HZ Delay is a character effect which means that it doesn’t do all things equally. It deliberately does some things oddly or not at all to allow it to have the sort of character so sought after in older analog gear.
The Windows and macOS versions of the TrackEssentials and BusTools (v3) plug-ins are enjoying their well-deserved retirement after being in service for over a decade and are now made available as freeware.
While you can de-ess your vocals, you can also reduce the harshness of your highs for your overall mix, cymbals and more! Instead of a de-esser, you can also use it as high frequency "tamer" to get warmer sounds.