Multiband Compressor uses

With the new MB compressor in SONAR Platinum 2016.04, I would like to ask some basic question about Multiband Compression.
 
1. What are some popular uses for it? What is most common?
 
2. What kinds of creative uses are people using it for?
 
3. What kind of problems can it solve that make it the best choice over other tools?
 
4. This may be redundant but, what can it do that nothing else can? Or is it just a case of being more convenient?
 
5. What situations would you reach for this rather than full band compression or a parametric EQ?
 
Thank you,
-Charles

I don't use multiband compressors anymore, having replaced them with more-versatile dynamic equalizers.
 
If you set the threshold low and apply a gentle knee, multiband compressors are good for leveling, especially on vocals and bass.
  
It can help mitigate acoustical issues, such as a vocal tracked too close to a wall. Similarly, it helps with inconsistent volume on a bass track, especially if the bass cab is miked.
 
You can use it as a de-esser when the offending sibilance isn't neatly contained within a single band. Along the same lines, it can be used to compensate for proximity effect when a singer has occasionally gotten too close to the mike.
 
I don't use it this way, but many do: glue compression on the master bus, where a multi-band can avoid pumping.

I bet Mr. Anderton would have something to say on this.

I can't think of any "creative" uses, which I take to mean sound-design. Like any compressor, its purpose is primarily corrective, to reduce something offensive. For example, I've used a multiband on a stereo drum mix where the hats were too prominent and I did not have access to the original tracks.

You really can use a MB on just about anything since you can choose the band crossovers and even how many bands to use.  I used it on my crappy, uneven bass playing frequently.  Create 3 bands, set crossovers as you see fit, and compress where needed.  I always play way harder higher on the neck, but don't want to compress my smooth low notes.  MB comes in handy for this type of stuff.

I think they are great and the can solve a lot of issues sometimes.  I like them in mastering.  You can get away with a full range compressor on most things on tracks due to the nature of the sound being less complex.  On full mixes multi band compressors can be better.
 
A couple of things worth doing with them though.  It is good to solo the bands and hear what areas you are effecting.  I find it helps.  Also be prepared to alter the crossover frequencies.  Don't just use stock settings because I have found altering them can give quite different results.  Solo the areas while you are setting crossover frequencies too.  Smoother more transparent operation results when tweaking the crossovers and bandwidths etc.
 
The multiband can tame just a certain area of your mix well.  It can also when confronted with a real nice mix just dance over all the bands and then it is nice to get all the bands doing equal gain reduction too.  The sound or EQ won't change.  You can still get into light conditioning over a well mixed master.  Small amounts of GR eg 1-2 dB, slow attacks and low thresholds like 1.5:1 in most of the bands. Release settings are important too.  It can impart a pro sound to your master.
 
It's cool to be able to alter the make-up gain of each band as you can turn it into a sort of nice active EQ as well.  I find I can use less mix EQ  (pre compressor usually for me)  using the make-up gains in the bands instead to fine tune a mix EQ.
 
It is nice to be able to alter the ratio and GR of any given band.  And then all bands locked together at times when making adjustments but also you have to fine tune bands individually too for best effect.
 
I like the Sonar Multiband a lot as I feel it shows you a lot of information in one look.  The Studio One multiband is a bit complex and it frightened me off at first but after a while I got all over it and it is excellent as well.  Mixbus has one of the best though.  What that can do is limit the amount of gain reduction ie it can be set so it never drops below a certain level which is actually great. Eg -2.5dB etc  Even on a loud segment, instead of a band dropping way down by crossing over a threshold with a large amplitude, it still does some GR but then stops at some point.  Overall mix EQ can be maintained well that way.  Some of the dynamic range is left in any one band. That is a cool feature, some multibands can’t do that.
 
 
 

Wow,
 
Those are some great responses. Thank you Danny, Jeff, dmbaer, mettelus, sven, b rock, and everyone else.
 
Danny, your detailed response really helped me understand. I think I get it now. Other responses helped clarify and confirm.
 
I used the new MB to tame the low frequency swell that happened on palm-muted parts in heavy distorted guitar. It would swell up on the palm-mutes but nowhere else. I put the MB on there and set it to reduce some low frequency by 3 or 4 dB, but only during those times. It really evened things out and work well.
 
Jeff, on this new MB that SONAR recently offered, it also has a "range" as you describe the one in MixBus having. You can set a limit to how much compression will take place. These two new plugs are really high quality and well designed.