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Mix Bus Compression Guide

Posted: Sat May 13, 2017 6:21 pm
by Lost to the Void
Right then, a simple guide here to compressing your 2bus/master bus.

Part 1:

1stly why would you want to compress your master bus? Don`t mastering engineers tell you not to?

Well, for dance music in general, and especially techno, master compression really is a part of the sound for dynamic drum based music, and you are missing something if you don`t do it *properly*. Mastering engineers tell you (if they know what they are doing and not just repeating shit they have been told or read online) to take off stuff from your master bus generally if it is effecting the dynamics where loudness is the consideration. A good mastering engineer should have no problem with compression done for colour and for creating dynamic movement. I have no problem with it as mastering engineer, providing it has been done properly.

What mix bus (master channel, or whatever you want to call it) compression can do for you is a number of things. It will glue the mix together, but also it can provide a cohesive glue to the groove of the mix, adding more movement to the overall sound that works sympathetically with the whole groove. It can add punch and that "secret special sauce" that makes the mix work.

To do so you will need a "musical" compressor, which I will explain later.

Do not be afraid of doing this, it actually is fairly simple a process.


So to begin with you want to "mix in" to your mix bus compression. That is, when you start making your tune, the compressor is sitting over the mix bus right from the beginning. That way your mix is always tuned to that compression. Adding compression later can change tonal balance and dynamic balance in ways you might not want.

So pick your compressor. For this example I will be using the Klanghelm MJUC Variable Tube Compressor. It`s pretty awesome and at 28 euros, crazy not to own it.
I also am attaching to this tutorial an example Ableton project (tough shit if you don`t use it) that you can download and look at. You will need the MJUC, but everything is with stock ableton plugins (latest full version, sorry crackheads) and stock ableton samples.

So, throw your compressor on to your mix bus.

1stly, once you have the basics of a groove down, some drums and bass and synth or whatever, we can start tuning the comp.

Take your bass channel and mute it for the time being.
Set your compressor attack to it`s fastest setting, set the release to it`s slowest setting. Dial the ratio to around mid way (roughly between 2 and 4 to 1).
Now with the music running, pull down the threshold until you get compression, we are going extreme first off, so keep lowering the threshold until you get around 6-8 db gain reduction.
Now slowly dial back the compression release until you get some pumping going on, continue doing so until the sound is pleasingly rhythmic and works with your groove (albeit in an extreme way).
Now slowly dial back the attack, you will hear the body of your kick drum returning, dial it back until your kick is comfortably back to the thump that it had pre-compression.
Now unmute your bass, this will probably throw everything out, so firstly you`ll probably want to reduce the bass channel volume a little to let the kick through and also to reduce the size increase the compression will have given it.
Next you want to find the sidechain control on your compressor, it might be called sidechain, hi pass, EQ, or sidechain EQ. But you want to hi pass/low cut out the low lows so your kick is the thing the compressor responds too rather than your deep bass. Normally 60hz or higher will do the job.

Ok, now dial back the threshold until you have between 1 and 3 db of gain reduction.

You may then want to retune the other elements in the mix just to re-address your overall mix balance, and possibly bring up the make-up gain on the compressor to return your tune to a decent listening level (or higher if you want).

That`s about it for the basics.
Now as you add elements to your tune and EQ them they will be done inside the compression and so will be made to fit.
Periodically check your levels going in to the compressor, you may need to pull down all your channel levels as you add tracks (always helps to have a meter before your comp on the mix bus, satson users will already be doing this (or other console emulation people), and/or adjust your compressor threshold to make sure the gain reduction isn`t rising above 1-3db (but never entirely returning to zero. You always want the compressor to be "working").

And that`s your deal.

Now some compressors are better than others, I use the MJUC as it mimics the characteristics of variable mu compressors, which respond in a program dependent way, so your attack and release settings work alongside to the way the compressor reacts, on it`s own, to the input. This would be called a "musical" compressor.

I`ll make a list of other great soft-compressors on another post in this thread, as they all exhibit different audio response and have different curves to the attack and release portion.

With the MJUC I recommend you start with the Mk2 setting as it is a good middle ground between the mk1 (very program dependent, fairchild like) and the mk3 (less program dependent, much more reliant on your attack and release control, a very modern comp), as it is a great place to start. And the example ableton project I include is using this comp on the mk2 mode.

Try just running the loop and switching the compressor in and out (I have gain corrected so the level stays the same, allowing you to hear the difference).
Without compression the groove kinda falls apart a bit, loses it`s swing, and the elements disconnect a little. Switch it back in and things start moving and swinging as the comp pushed and pulls the sound, and sticks it together a little.

Any further questions, stick em in the thread. Maybe someone can sticky this as well, as I still don`t think I can.

Part 2: Further down this thread

Re: Mix Bus Compression Guide

Posted: Sat May 13, 2017 6:32 pm
by Críoch
Thanks Steve.. Stickied 8-)

Re: Mix Bus Compression Guide

Posted: Sat May 13, 2017 7:31 pm
by xonetacular
Klanghelm should give you a commission since I just bought that plugin without hesitation. Thanks for this guide, will play around with it.

Re: Mix Bus Compression Guide

Posted: Sat May 13, 2017 8:18 pm
by Alume
Yes!!!

Edit: thankssssa!!!

Re: Mix Bus Compression Guide

Posted: Sat May 13, 2017 8:23 pm
by Root
Wow, thanks for sharing this!!

Re: Mix Bus Compression Guide

Posted: Sat May 13, 2017 8:34 pm
by dubdub
Thanks, when I have some time I will give this a shot and report back.

Re: Mix Bus Compression Guide

Posted: Sun May 14, 2017 12:20 pm
by Prophän
Thank you for sharing

Re: Mix Bus Compression Guide

Posted: Sun May 14, 2017 5:53 pm
by reflektah
Thanks for sharing! Tried it on a live set I'm working on and it seems to tighten things up pretty nicely.

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 12:18 am
by ekwipt
thanks mate

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 2:13 am
by Pelecaras
Cheers for taking the time to post this buddy, much appreciated.

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 9:18 am
by totalcult
xonetacular wrote:Klanghelm should give you a commission since I just bought that plugin without hesitation. Thanks for this guide, will play around with it.
^ Exactly this.

Thanks for this.

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 9:38 am
by victer
Thanks a lot for this guide !
I will definitely try this very soon.

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 12:22 pm
by bram2000
Amazing, thanks Steve! Insta-buy on MJUC over here too :)

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 12:47 pm
by Mslwte
That's gold. Thanks for sharing with the forum.

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 3:05 pm
by Plyphon
Nice, will try this later with the stock ableton compressor as I am a cheapskate

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 3:38 pm
by Lost to the Void
Plyphon wrote:Nice, will try this later with the stock ableton compressor as I am a cheapskate
Stock ableton compressor is no good for mix bus compression, the attack and release has no character at all.

Glue comp would be a better choice.

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 4:37 pm
by 1nfinitezer0
Lost to the Void wrote:
Plyphon wrote:Nice, will try this later with the stock ableton compressor as I am a cheapskate
Stock ableton compressor is no good for mix bus compression, the attack and release has no character at all.

Glue comp would be a better choice.
I happened to try this just for comparison, and yeah wow, the difference is huge. A very useful thing to observe. Although the stock Ableton Comp had more fine-tuning accuracy for settings than the glue, the trade-off in sound wasn't worth it. Sounded less smooth and groovy, did not play as nice with the highs (which I have a general challenge of getting too harsh anyways).

Steve, you gave out a glue preset a good while back with similar settings to this. Only difference was a 50Hz HPF IIRC.

Is the MJUC fast and stable enough to use in on live performance master channel? Love the SDRR, getting this is more when than if ;)

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 4:41 pm
by Lost to the Void
Right

Part 2:

In part 1. I explained how to apply compression to your mix for musical effect (we aren't limiting peaks here, we are creating movement). Hopefully the way I have explained it means that as you go through each stage of the guide, you are hearing the changes and understanding what is going on.

What I haven`t done is explained what is actually going on, so here is the nerdy technical explanation of what is happening. Hopefully in laymans terms. My goal is that with part 1 reinforced by part 2, you will more fully understand the process, and it will help you adjust to all your different tunes, and also give you a clearer understanding of compression. Some of these techniques can be applied for track or group compression also, but we`ll cover that later.


Ok, firstly I was very careful not to give you any dial settings (apart from with ratio) so that you aren`t just applying presets I tell you to apply, and you are using your ears to tune the compression, which is always the best way (although having accurate VU ballistics can also help, as reading the VU of a compressor is something you learn to do, providing you understand the VU ballistics).

So, what is happening, and what you are doing is this.

The compressor is acting as soon as any signal crosses the threshold which you set, therefore compression is dependent on input level (which is why I can`t tell you what to set your threshold at).
Once the threshold is crossed, the compressor begins to act.
The attack controls the amount of time it takes the compressor to reach maximum gain reduction (which is dependent on the compression ratio).
The release controls the amount of time it takes for the compressor to reach zero gain reduction once the level has gone below the threshold.
This is a very misunderstood part of compression.

*A compressor is only ever attacking, or releasing. People misunderstand attack as being the amount of time a compressor takes to act, but the compressor is always acting when a signal crosses the threshold, you merely control how long it takes to get to maximum compression, and how long it takes to get to no compression*

So, your stereo signal crosses the threshold and the compressor starts to act,
lets assume we have the attack at it`s fastest setting as in the beginning the tutorial,
so the compressor is reaching it`s maximum gain reduction instantly (not exactly true, but for the sake of the discussion let us say it is so), the ratio is controlling this. Ratio of 2 to one means for every 2db over threshold, one is allowed past.
Lets say the part of the stereo signal driving the highest gain is the kick drum, so the kick drum is triggering the compressor, once the kick drum is gone, the signal is now no longer above the threshold, so the compressor now wants to release to zero again reduction. The release is controlling the speed of this process, so as you reduce the release speed, the compression is returning to zero more quickly. Timing this release to act with the groove means the gain reduction is causing level pumping in time with the groove, adding a pleasing movement and enhancement to the groove.

Now currently the attack is so fast, the compressor is compressing straight away, this means the attack portion of your kick, and all your other sounds depending on the transient to define them (transients are important and contain a lot of audio information in a very short time duration) have been reduced to the same level as everything else.
So you have reduced all the dynamic interest, and even though the tune is now pumping, there is no vitality and punch to the sounds.
So this is why we dial back the attack, as we slow down the reaction speed in the race to reach maximum gain reduction, we are allowing the attack portion of our drums and synths to pop through the mix. So really you just slowly dial the attack back until the mix sounds comfortably punchy again, switch the compressor in and out to check against the uncompressed signal. And then we have the best of both worlds, dynamic movements from the pumping, and all the transient punch still intact.

So this is why more programme dependant compressors are better for this purpose.
Stuff like variable mu compressors - which is compression where the ratio increases with gain reduction, and is thus signal dependent, so the louder the transient the harder it is compressed - are great because they are reacting more closely with the state of the signal, giving more interesting movement.

Then you have compressors where the attack and release curves are non linear, again giving more interesting movement. Some even have attack and release phases that again, are signal dependent, and so they react more quickly to a loud signal than a quiet one, even if you also have control over this, like the MJUC, they are still also reacting to the programme material.

These quirks are why compressors such as the infamous Fairchild, are so well revered in mastering. Being a variable mu that actually uses tubes to apply the gain reduction makes the Fairchild very musical. It`s as noisy as all shit, but it is very musical in its action.

And this is why I recommend the MJUC, being a vari-mu based compressor (if you use the MK1 setting, this mode more closely models the type of behaviour exhibited by a Fairchild or Manley, which is great, but really more appropriate for mastering than creating mix movement) that also has reactive attack and release that you can also control to varying levels of strictness (Mk3 mode being the most strict in the level of control you get given against the program dependence).

In my next post in this thread I will list some other compressors that have more interesting non-linear behaviours that are great for the mix bus.


Also, additionally, if we apply the techniques from part 1 of this tutorial to a drum bus, with a few adjustments we can dial in New York/Parallel compression to drums.

So firstly what you are doing with NY compression is a specific technique developed in hip hop, for really adding serious mojo to a drum bus.
You basically employ exactly the same technique as I have already written, but you keep the gain reduction at a high level, you aren`t dialing back for subtlety, you are going for crazy extreme, in your face movement, think 5, 6, 7 or 8 db of gain reduction, you can even keep the attack fairly fast so the drums get more size (but lose punch).
Then all you do is dial back some of the original signal (generally a good bit of it) so you get really big, swinging drums, but all the snap and tightness of the original signal is present.

Don`t do this on your master bus though, it`s too much, it will mash your whole mix in a way that will cause all sorts of level and eq problems and you will spend another tunes worth of production time trying to get all the elements to balance, as everything will be fighting everything for space, and even then you will end up with weird transient smearing and peak conflicts......

Ok, part 3 when I have the time....

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 4:50 pm
by Lost to the Void
1nfinitezer0 wrote:
Lost to the Void wrote:
Plyphon wrote:Nice, will try this later with the stock ableton compressor as I am a cheapskate
Stock ableton compressor is no good for mix bus compression, the attack and release has no character at all.

Glue comp would be a better choice.
I happened to try this just for comparison, and yeah wow, the difference is huge. A very useful thing to observe. Although the stock Ableton Comp had more fine-tuning accuracy for settings than the glue, the trade-off in sound wasn't worth it. Sounded less smooth and groovy, did not play as nice with the highs (which I have a general challenge of getting too harsh anyways).

Steve, you gave out a glue preset a good while back with similar settings to this. Only difference was a 50Hz HPF IIRC.

Is the MJUC fast and stable enough to use in on live performance master channel? Love the SDRR, getting this is more when than if ;)
Yeah, with a good compressor, fine control on the mix bus isn`t really necessary, broad subtle strokes.....

Yeah I`ve done a couple of PA`s, my last 2 using ableton before I dumped the laptop for live, using the MJUC, though setting is much more of a fine art unless you have done good prep on your material beforehand (or are doing a lot of fine EQ work on channels as you play).

Re: Mix Bus Compression Guide

Posted: Mon May 15, 2017 8:04 pm
by Aureliano
Void, massive respect and thanks for this thread. You legend.

I gotta ask, although it could be a stupid question...

If my kick patterns change in a track, should I automate the mix bus compression for each section accordingly? For example, I sometimes write tracks that have a 4/4 kick pattern and, say, a DnB kick pattern; I like the contrast and locking into different grooves within a single song. I'm about to go experiment with it now so I may find my answer, but theoretically speaking, I'm wondering whether I ought to loop sections of the song in order to find the appropriate mix bus compression pump for that section...but then that could affect the total mix in a strange way. I don't know the answer but I'm sure someone here has experience trying something like this.