Compressors 103 – Going deeper

Today I’m going to go a little deeper into how compressors work. But first, I want you to do an experiment. This experiment will allow you to SEE what a compressor does. When I did this, things started to become a lot clearer for me. We have to listen differently when it comes to compressors. We are not listening for frequency, we are listening to dynamic changes (amplitude, loudness).

For this experiment it would be better to use a bass track. The reason for this is one, we ALWAYS use a compressor on a bass track and two, the reasons to use a compressor on a bass track is because we want to control the initial attack of a note and lengthen the sustain of the notes, as they fade out quickly. Try to use a track that has a regular-type bass line, not one that is super busy.

1. Find a bass track (or create one using a VI).  If a virtual instrument is used, use one that emulates a real bass guitar, not something like a synth bass. What is needed is a sound whose initial attack is strong (loud) and whose note decays after the initial onset of the note, like a real bass. Also, the track will need to be printed. For this test to work we need an audio clip, not a MIDI clip.
2. Put a compressor on the bass audio track.
3. Set the ratio to something higher, i.e. 6:1. Set a fast attack, i.e. 3 ms; fast release, i.e. 18 ms.
4. Lower the threshold until the meter shows roughly 8 dB of gain reduction. Then add some makeup gain. Set this to the amount being reduced. If the gain reduction meter shows 8 dB of reduction, set makeup gain to 8 dB. This way the volume remains the same.

What you should start to notice is that the initial attack of the notes (when the player first strikes the notes) no longer punches. Now the dynamics are a little flatter, smoothed out. The second thing you should notice is that the notes are more sustained. You will no longer hear the decay, but a nice solid note that holds out for it’s full duration of note value (i.e. quarter note, half note, etc.)

NOW, print the track again with the compressor engaged. What you should have are two printed bass tracks. One without compression and one with compression. Look at the differences between the two. The first track has a pronounced attack with high amplitude and fast decay. The second, the initial punch is now all or mostly reduced and the sustain of the note stays strong longer. Below is a picture of what this should look like. 

I have done exactly that here. I used an Instrument track with Trillian Bass module – played a bass line – printed it – ran compressor with 6:1, 3 ms attack, 18 ms release, 8 dB gain reduction, and 8 dB make up gain. I think this helps to drive home what a compressors job is. In this example my goal with the compressor was to lessen the attack and give it more sustain. If you want to see what the compressor does even more obvious than this, use the fastest attack possible, with 8:1 ratio, with a lower threshold for more gain reduction (10 dB).

I hope this helps – it did for me! Next time I will start to go into specific parts of a compressor, i.e. threshold, knee, attack, release, etc.

As always – HEY! Make it a great day!
Tim

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Compressors 102 (More of the Basics)

After learning the basics about compressors (see Compressors 101 earlier blog entry), then you can use this general guide of the type of overall effect you are going for.

If you want a Natural sound (the compressor is not noticeable):

Use a slower attack (longer than 75 ms) and gentle ratios (less than 2:1). Always allow the compressor to “relax” back to zero several times a measure.
For a Punchy Response:

For a harder, punchier sound, use higher ratios and thresholds, but keep an ear out for any distortion.

If you want a Thick and Dense sound:

For a thicker, denser sound use faster attacks, medium ratios, and lower thresholds. There will be much more gain reduction though.

If you want a Pumping Effect (for EDM, for instance):

For an overstated pumping effect use fast attacks, high ratios, and a longer release time.

DO – Avoid using extreme settings to begin with. This is especially true if you are just trying to control the dynamics.

DON’T – Add compressors to every channel just because you think you’re supposed to! Start with minimal compression and carefully choose where, when and why to add a compressor.

DO – Experiment with different kinds of compressors. There can be some big differences!

DON’T – Don’t forget to bypass the compressor occasionally to check that you’re getting good results.

DO – Remember to balance the output gain so the level doesn’t change when you engage the bypass. In other words the before and after volume level should be the same. We hardly ever use compression without changing the output makeup gain. If you add 3 dB of gain reduction (GR), then you should be able to add 3 dB or so of make up gain for the output.

DON’T – Don’t be afraid to experiment. Some of the greatest sounds in the history of recorded music came from misused and abused compressors!

The next blog about compressors I will talk about the “Knee” of a compressor! I really do hope this helps. It helped me!

As always – Make it a GREAT day!

Tim

Compressors 101 – the Basics (part 1)

Compressors seem to confuse a lot of people in the beginning, they certainly did me! Here is some helpful information concerning using a compressor in your mixing to help get you started. I will have other blogs on compression, so keep a look out!

1.  Decide what you want to achieve. There are really only 4 reasons for using a compressor – control a dynamic signal, add punch or impact, change the sound, create an unusual effect. Make a decision on what your goal is, which one of the four you would like to achieve. Keep listening with your final goal always in mind. Here is a neutral starting point: 2:1 ratio; 75 ms attack; 100 ms release.

2.  Overdo to begin with. Pull down the threshold until it starts working. It can be helpful to start with exaggeration. If you’re having to turn the threshold way down – boost input level instead. Exaggerating can help get settings right.

3.  Listen. Fine tune settings keeping end goal in mind. Once you get close, adjust the threshold.

4.  Listen again and balance different settings against one another. Higher ratios usually need higher thresholds. Lower ratios usually need lower thresholds.

5.  Experiment. Don’t be afraid to change a setting. Just keep listening! Radical amounts are common: 15-20 dB for electric guitars, room mics, drums and even vocals.

For a smoother sound – Use faster attack and higher ratio (But don’t lose energy & excitement)

To reduce ‘bounce’ – Use shorter release time & ease off threshold, or use a lower ratio. Bounce is when you hear the level ducking as the compressor kicks in and then springs back up when it releases.

To add punch – Use a higher ratio, slightly longer attack and shorter release times, but watch out for pumping. Pumping is where the end of the note is louder than the start. Also when adding punch, be careful not to introduce any distortion.

If you add stereo buss compression – be gentle – 1.5:1 and only 2 – 3 dB of gain reduction.

Don’t be afraid of using compressors. Experiment with them until you understand them. Try this experiment: print a bass track with heavy compression. Compare the original audio track with the compressed audio track. This will help you understand just exactly what the compressor is doing. You will see a visual representation of what your ears are telling you.

Compressors are a vital part of making music. We use them while tracking, mixing, and many times both tracking and mixing.

I hope this helps!

Peace – and as always – make it a GREAT day!

T