Pro Tools 10 - DIY Multiband Compressor

How to Make a DIY Multiband Compressor in Pro Tools

My custom Multiband Compressor

For all of the greatness of Pro Tools 10, Avid is missing a critical element: the Multiband Compressor.  Actually, I would prefer a high-grade Dynamic EQ if I had a choice between the two (one that doesn't create phase issues, such as the Linear Phase Multiband by Waves).

Of course, there are plenty of third-party plugins available to purchase separately and integrate into PT10.  Waves, iZotope, and Blue Cat are a few of the brand names you may be considering.  However, for those of us on a budget it's not always practical to shell out $250-$500 if there's a workaround.  This brings me to my focal point for this article: let's learn how to create a Multiband Compressor without spending a dime.

The goal is to achieve dynamics control over individual frequency ranges as opposed to the entire mix.  This will allow you to fine tune how the bass comes through, blend the low-mids and hi-mids together with ease, and bring up just the right amount of controlled highs to obtain presence without harshness.  Moreover, this can be done for one track, several tracks, or even an entire mix.  The pictures from this article are from the DIY Multiband Compressor I created for my most recent instrumental mix, Alien Resurrection.

The concept is extremely simple.  Here's a step by step breakdown:

1) Route the output of the tracks you want to compress to a stereo bus.  (In this example, Bus 1-2)

2) Create 1 new stereo auxiliary track and set its input source to the bus from Step 1.  Then send it's output to another bus.  This will allow you to process the sub-mix of the source tracks prior to compression if you'd like.  (In this example, Bus 9-10)

3) Create 4 new stereo auxiliary tracks and set their input source to the bus from Step 2.  Leave their output set to Analog 1-2, which is the standard output.

4) Place an EQ on the 1st track with a Lo-Pass Filter at 120 Hz @ 24 dB/oct.

5) Place an EQ on the 2nd track with a Hi-Pass Filter at 120 Hz and a Lo-Pass Filter at 1.5 kHz, both @ 24 dB/oct.

6) Place an EQ on the 3rd track with a Hi-Pass Filter at 5.0 kHz and a Lo-Pass Filter at 1.5 kHz, both @ 24 dB/oct.

7) Place an EQ on the 4th track with a Hi-Pass Filter at 5.0 kHz @ 24 dB/oct.

Notice how each track is broken down to represent only one portion of the frequency spectrum.  This is the critical aspect of obtaining multiband dynamics control.

8) Now place a compressor on each of these four tracks.

(Note, in the picture below it shows a second EQ I placed on my Low frequency band... this was to further cut out sub-harmonic noise below about 30 Hz that I did not want to be compressed.)  Altogether, your track inserts should now look something like this:

I really like the "Channel Strip" Compressor that comes stock w/PT10.  It also has a few other things, such as a noise gate, EQ, and volume controls. (Workflow Tip: You could even set up the EQ cuts in Channel Strip instead of using separate EQ plugins, so long as the signal routing hits the EQ first and then the compressor.)

The Channel Strip in PT10 is very powerful and musical.

9) Now set your compressor how you like it on each of the 4 tracks

Ratio, Threshold, Knee, Attack, Release, and Gain are your main controls, and you can read more about how to use these in this article about parallel compression.  You may want to experiment with different compressor settings for each frequency band, and perhaps even different compressor plugins.

10) You're done!

Congratulations, you successfully created your own Multiband Compressor and now you are ready to "mix together" the various frequency bands.  It may take some continuous tinkering with compressor settings, fader levels, etc., but eventually you should be able to achieve the type of control you're after.

You may notice in the picture above that I applied some processing to my uncompressed sub-mix before sending it to the compressor.  That's because in this context, I was using my DIY Multiband Compressor as a master compressor to control levels of the entire mix.  Hence I wanted to throw some harmonics processing, reverb and EQ on before master compression (in this case, anyways - it certainly doesn't always have to be that way).  By the way, one big reason for putting reverb pre-comp is that this song has a fairly ambient environment and I wanted to bring up the volume of the reverb tails as much as possible.  I also added more harmonics processing and limiting to the entire mix after multiband compression, which may seem a bit extreme, but I was using very subtle settings.  Ultimately, I found it to be more musical to have very subtle processing 2-3 times during the chain rather than heavy processing at any one point.

One really cool feature of just about any multiband compressor is that you can adjust the frequency range for any given band.  For example, instead of setting the low mids from 120 Hz to 1.5 kHz, you could do 150 Hz to 1.25 kHz, or whatever.  And with the DIY multiband compressor, you aren't limited to just 4 bands - perhaps one very narrow range of the frequency spectrum is giving you problems... well, add a fifth band for that narrow area and build the other 4 bands around it.  That said, usually 4 bands is enough to get the job done, and if you get too wild you may introduce noticeable phase issues unless you start using a plugin that eliminates this phenomenon.