Let us learn to set up the parameters of a sidechain-compressor Waves C1 comp sc. This is one of the plugins, which I often use when mastering my tracks. I use it to add some certain dynamical pumping feel to the track. I also must add here, that this plugin can be used not in all cases, not in any track. In some cases using this plugin can lead to unwanted volume level duckings of your master sound.
However, if you are not sure, just try to insert this plugin into the master chain and set it up, and then by switching it on/off several times try to compare, how good or bad your track will sound with it or without it. It is possible that you will not hear the effect of this plugin at the first time. It will come with some experience. But the plugin performs its function. I use it in those cases, when my mix sounds too flat in dynamical sense. For example, when bass drum doesn't bring enough pressure in the mix and just go next to the mix, while not making some feel of a kick or punch.
And now let me describe how the plugin works. Any sidechain compressor works like it simply compresses the sound with accordance to some external sync signal. In our case Waves C1 comp sc will be driven by a sync signal of a bass drum kick. We will set its filter that way, so it will be controlled by the main low frequency of the bass drum of our mix in about 50 - 120 Hz. A compressor must be set up that way, so it must pass the first front of a bass drum kick unchanged, and later, after some very short time, with a small latency began to work by decreasing the volume of our mix. Then, somewhere after the middle point between the two kicks of the bass drum, a compressor must release the volume of our mix back and return it to its normal state. The result of all these actions will lead to so called "pumping" effect of our mix. This process will repeat automatically each time after every kick of our bass drum.
And now let's get closer to business. Below at the figure you can see C1 with the settings, that are maximally close to those, which I usually use in mastering.
To begin, you must set the EQ mode parameter to "Sidechain".
Threshold. I set this parameter in the following way. When a bass drum hits, the red indicator of compression must jump to -3...-5 dB (as shown in the figure above), and in a moments between the bass drum hits this red indicator must be minimal and close to zero. It provides reacting a compressor only on a bass drum kick, and not on other parts like a bass line for example. If your sidechain compressor will react on bass line (red indicator will drop down enough in the moments between the bass drum kick), then instead of pumpin effect you will get only some random unwanted volume ducking of your mix. If you have this situation, then it means that you possibly incorreclty tuned up the plugin, or maybe you incorrectly mixed a bass drum with the bass line in your music (they are conflicting by frequency or by volume; you should try to rise up or down the volume of the bass drum or the bass line). Also, here can happen a following situation. If you have a very loud and deep bass line in your track, then you will probably not be able to process your mix with C1 plugin at all, because you will not be albe to make the plugin react only on the bass drum and not on the bass line. In this case simply don't use this C1 plugin in the mastering of this track.
Ratio. This parameter defines how strong a compressor will duck down your mix volume when a kick drum will be played. The more ratio, the more strong will be the compressor's action. I set it in a range of 1.50:1 to 3.00:1.
Attack. Defines the time of a delay between the moment when compressor "detects" the bass drum kick and the moment when compressor starts to react. The more parameter's value, the more part of the kick drum's beginning a compressor will leave unchanged. With a minimum setting of attack you will hear only a short high frequency click instead of your kick drum. It sounds not very good. When you start to increase the attack, you will start to hear also some part of the bass drum kick. That's what I'm trying to achieve from C1. I usually set this parameter in a range from 5 to 30.
Release. Defines the time amount, after which a compressor releases the volume of the mix, returning it to its initial normal state. I usually set it in about 20 to 70.
Freq. This parameter sets up the frequency of a filter. We must set this parameter that way, so it must maximally correspond to the most loud frequency of a bass drum kick sound. It can be done by adjusting the Freq parameter in a range between 40 - 120 Hz. When a correct frequency is set up, the red indicator of the plugin will react (drop down) only when a bass drum hits, but it will remain around zero value between the kick sounds, not reacting to the track's bass line. If a red indicator reacts not only to the bass drum, but also moves randomly when onther sounds like bass lines are played, then it means (as I mentioned before), that you incorrectly tuned up the compressor. Try to experiment with the settings of the Threshold, Freq and Q parameters.
Type - filter type. I usually use a bandpass filter (as shown on the figure). You can also use a low-pass filter, sometimes it can give you some good effect.
Plugin Waves C1 comp-sc is placed into the master section of your project before the plugins Izotope Ozone and Waves L2. In the next articles I will show you how to set up the other plugins that I use when mastering my tracks.