IMHO a "de-esser" is an ineffective tool, as a rule, although it can have some uses for controlling minor sibilance. You can also decrease sibilance by changing mic position, so the singer is singing more off-axis, *past* the mic capsule, rather than *at* it. The problem is, both of those techniques mess with the sound, more so with some mics than others. Most people don't want to hear the real answer, but here it is- the singer needs to change his or her diction. You actually have to think!!! while you sing, and shorten/lighten every S sound you make. The point is- the way you pronounce words when you are speaking is not how you do it when you are singing into a mic. Really good mic singers will also shorten dipthongs, words where you are transitioning from one vowel to another, such as "ow" or "boy".
This lesson is a sub-group of a bigger lesson. The fact is, the skill set of a live performing musician and the skill set of a recording artist aren't the same. In fact, many of the things you do on stage that make you successful work against you in the studio. Unsuccessful performers take the attitude that they are just great, and it is the studio's job to translate that into a recording. The good ones figure out that no matter how good you are on a stage, you have to learn different skills to make really good recordings. There is no magic wand, including a de-esser, that can make sibilance go away, and worse, while it is making *some* of it go away, it is also eliminating sounds it didn't need or want to. You have to learn to change the way you pronounce words, it's that simple, and that difficult. Some people have 2 dictions- speaking diction, and microphone diction. Listen to John Lennon. He changed diction like most people change T-shirts. He had literally dozens of them, which were created for specific songs. That's what comes from standing in front of a mic that long (and being a genius).
That's one of the advantages you gain from working in a cover band for a while. You can't make your voice sound like 50 different recording artists. What you *can* do, is copy their diction. Trying to copy John Lennon's diction, for me, and Roger Daltrey's,Jim Croce's, Cat Steven's, Glenn Frey's, etc., turned out to be the best tutorial I ever got in mic technique.-Richie