Home Recording Weekly

For a better mix, compress it!

I have been putting in some long hours doing just what I love to do most, writing and recording music! I have been working on some bass, drums, and vocal tracks lately, that just wont “fit” into the overall mix. The audio spikes drive the meters into the red, and the “belly” of the sound just gets lost. Levels seem to rise and fall at random, and the whole mix almost gets tossed out.

If this sounds familiar, than I urge you to please try using compressors on your tracks. I am not trying to convince you to flatten out all of your music, but, shaving off the peaks can do wonders. Plus, compressing the audio can bring the over all levels of the tracks up in your mixes. However, modern computer based DAW's (with monitors) have changed the way we use add and/or use compression. Most of us now look at the waveforms of our tracks, or the peaks and troughs, and then add compression until the dynamics are flattened. You must not spend your days “looking” at your audio to see if it is flat or dynamic. Let your ears do this part of the job. I have fallen into this trap myself, so believe me, let your ears work like they should!

Most often I use compressors in either one or two ways. Either I place a compressor in an audio track after it has been recorded, in order to control an unruly bass or drum, and then I re-record the track with the added compression. I also place a compressor across the main outputs (or the master fader) of a whole mix. Both of these methods can help to raise the overall levels of the audio by removing audio spikes. This means that we can manually raise the levels too, since there will be no spikes to push the meters into the red. This is what folks mean when they talk about “getting a louder mix”.

The only other way that I have ever used compression is across an incoming signal. Most often I place a compressor across an incoming guitar for leveling the notes of a solo, as I record it, or to level out a rhythm guitars' spikes as I record it. The problem with this style of compressing is that it cant be tweaked later, or ever removed since it has been recorded.

Let's dive in, shall we?

Compressors are wonderful tools for the home recording studio. Used properly they work like magic as they bring our tracks together, and make mixing unruly audio a snap. However, you must know how to use compressors in order to get good sounding tracks, and to avoid any unwanted “pumping” from over compressed tracks. The question that I am most often asked is “What compressor settings work best?”. Well, there are no settings that work best, it is all in what you are looking to accomplish with your compressor. So, lets quickly look at what the dials on compressors actually do.

Most compressors share the same basic controls. These controls are for attack, release, threshold, ratio, gain, and some will have a "hard to soft knee" dial as well. Let's see what these are for.

The first knob or dial that we should tackle here is the “threshold” dial. The “threshold” is the spot (or level) in your audio where you want the compressor to “engage”, or to start compressing the unruly audio. This is set at the point that is most often looked at as a “peak” in your audio track. This can be the pick noise from the bass track, the crack of a stick hitting the snare, a spike in your vocals, or any such sharp and sudden noise.

The next setting on compressors that I want to write about here is the ratio. The ratio is basically how much you want the compressor to compress once it is engaged. There are most often times settings “pre set” on the face of the compressors, which are most often times used in studios. But, this is not the rule. Common ratios are 5:1, 3:1, and the like. Like the name implies, the audio is compressed in level by the ratio of incoming level versus the ratio setting. Follow the link below to get a better understanding of ratios.

This is a better way to say all of this, taken from the Sound on Sound website.....

“Ratio: When the input signal exceeds the Threshold set by the operator, gain reduction is applied, but the actual amount of gain reduction depends on the 'Ratio' setting. You will see the Ratio expressed in the form 4:1 or similar. Ratio is based on dB, so if a compression ratio of 3:1 is set, an input signal exceeding the Threshold by 3dB will cause only a 1dB increase in level at the output. In practice, most compressors have sufficient Ratio range to allow them to function as both compressors and limiters, which is why they are sometimes known by both names. The relationship between Threshold and Ratio is shown in Figure 2, but if you're not comfortable with dB or graphs, all you need to remember is that the larger the Ratio, the more gain reduction is applied to any signal exceeding the Threshold.”

The “attack” dial is how fast or how slowly the compressor starts to compress your audio once it reaches the set threshold. So, once the audio raises above the set threshold, the “attack” level tells the compressor how fast to compress the above threshold audio. The faster the “attack” time, the faster the audio is compressed. The longer the “attack” setting, the longer it takes to start compressing the audio.

This brings us to the “release” setting. The release tells the compressor how long to keep on compressing the audio once it has been triggered. The longer the setting, the longer the compressor is lowering gain levels, before it waits for the next signal above the threshold. The shorter the release setting, the quicker the compressor stops working once it has been triggered. The attack and release work together, and need some “play time” to really get the hang of. Listen to your compressor working as you play with the attack and the release.

The last knob or setting that I wish to write about is the “gain” setting. This is not rocket science. The compressor works at removing the audio that is considered a spike. The compressor works at leveling off our audio to a better “flatter” level of consistency. Since the over all level of our audio has now dropped, the gain setting will bring it up to the desired level. Basically, the gain allows us to bring up the level of our freshly compressed audio, back, perhaps, to where the spikes were in the first place. The compressed audio will now sit in the mix better as it can be heard at one nice constant level.

Once more, too much compression will take the dynamics of our tracks away. Dynamics are the quiet parts compared to the loud parts of a signal. Proper compression will only “shave off” the unwanted spikes and leave the rest of the audio as is. This is the secret of using compression correctly.