[Rwp] Dynamic EQ

[Snowman]

Well, I know this list is not about such things.  But, since we were buzzing a bit about this Dynamic E Q plugging, and I was flagrant enough with mad money to buy it, even though I don't really need it, I thought I would jot down what I have learned about it in the little time I have actually had to play with it, in case you were curious, just to give closure.

This is not multi-band compression, as we all suspected.  Instead, it is a toy for playing with the stereo spread of your mix, to make it sound wider, or mor enarrow.
It uses the concept of M signals, and S signals.  Such terms are actually common, I guess.  But, if you are not familiar with it, the M signal is the summation of left plus right.  S is left minus right. 
And, this tool is about making dynamic combinations of m and s.  When just running normally, with all gains constant and at unity, you can dig up your basic algebra, and use a little simple mathematics to return to left and right, since 
m plus s,
which is really (l+r) + (l-r) 
yields 2*left, 

Likewise m minus S yields  2*right.  

To support this, the tool gives you two filters.  You can choose the style and frequency for each filter.  The m signal passes through one filter, and the s signal passes through the other, and they are combined at the wet output.  Yes, there is a wet/dry mixer as well.

In addition, each filter has a trigger signal, which is a copy of the original input, with it's own trigger filter style and frequency.  So, now we really have 4 filters, two for each section.

The trigger for the M  section is a mono signal, l plus r, passed through the M trigger filter.  The amplitude of that trigger output can be used to either increase, or decrease the gain of the main M filter band.  It doesn't sharpen the filter, it just modulates the gain of that filter output.  

Likewise, the S section output is modulated by the S trigger filter output.  The S trigger input is the original l minus r signal.

The output of each trigger is fed into a circuit that gives you control over threshold, attack and release.  

You can solo any of these signals, and will notice that the S trigger contains no audio if you feed it a mono sorce panned to center, because the two channels cancel one another out.
But, when you pan left or right, you start turning up in the S trigger, with a phase inversion depending on which side you are panned to.

The basic idea for widening or narrowing a mix, is that if the gains of the two stages, m and s, are equal, the resultant output will be a regulard stereo mix, with middle being middle, hard left being hard left, and hard right being hard right, just like normal.
But, if you change the relative gains between the m and s sections, then only partial cancellation occurs, or too much cancellation, in which case you start hearing out of phase stuff, which kind of makes it sound like it is behind you.
So, they use the outputs of these triggers to modulate those gains, and make the mix fluctuate in sync, or sort of in sync, with the dynamics of the program material.
You can hollow out the middle, and force more stuff to the sides.  Or you can do the opposite.  
It's a cute little tool, and you can probably create some interesting effect with it, if you are into that sort of thing.

But, you can also just use one section, such as the m section, just as a regulared 2 track stereo, and just modulate the gain of that filter by it self, or in combination with the dry signal, to get partial effects,  like an acoustic guitar that gets a bit brighter when a bass note is hit, just to keep the upper notes from getting buried.  Just set the m trigger frequency down in the bass range, and use it to expand the m filter, with its frequency set up high, and a wet dry mix to fill in down low where the filter doesn't go.

Yes, this tool can be a nice little single band  compressor or expander if you want it to.  But, you've already got a few of those.

Anyway, for what it's worth, that is what I know about it.

 


 
 
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