I have spent the last few months going over the basics of HOW sound systems. All of you have varied levels of proficiency with regard to your sound technician skills; however, going over basic principles is a good thing. Do you ever ask why your priest, pastor, rabbi, etc., has gone over some of the basic tenants of your particular religion more than once? Their purpose is to build a strong foundation for your faith. Well, it’s the same in worship sound. Obviously, not as lofty, but we can agree that a solid foundation to our work (volunteer or not) is a good thing.
That said, on with this month’s installment. I want to take a closer look at your average compressor. More than likely you have one of these in your outboard rack. If you don’t, talk with your worship leaders about purchasing one. A compressor is also known as a dynamic processor. It is designed to automatically control the volume or dynamics of the sound traveling through it. Compressors can improve the intelligibility of vocals and control where instruments are placed in the overall mix.
Understanding the Parameters
To understand how to properly use a compressor we will need to understand the parameters of this piece of outboard gear. I have no idea what make or model you have in your house, but I will touch on the five main elements of compression: threshold, ratio, attack, release and gain or gain make-up.
“Threshold” is defined as the point where compression begins. Turning your threshold knob to the right will raise the dB level as to where the compressor kicks in. Turning this knob to the left has the opposite effect. In a high-threshold setting you will only be compressing the up decibel levels of your audio signal. As you lower the threshold, more of the audio signal will be compressed. Setting your threshold knob to the center position is a good place to begin. Then use your ear as you raise or lower the threshold.
“Ratio” will be our next concern. It is the difference in decibel reduction from the input signal to the output signal. Your compressor’s ratio knob typically ranges from 1 to 10. For example, setting the ratio at 2 creates a 2 to 1 ratio (2:1). This means that if 2 dB of signal enters the compressor above the threshold setting, 1 dB exits the compressor. A 4:1 ratio lets 4 dB in and 1 dB out. With these two parameters we can now adjust when we capture the signal and how much we compress it.
Our next adjustment would be “attack.” This controls how fast the signal is captured and operates in milliseconds (ms) — 10-25 ms would be a very fast attack. This is good for removing the sibilance or sizzle from a vocal, making it more intelligible. Slower attack times have a multitude of uses. Once again, this is a good time to use your ears. Once you have captured the audio signal you have to decide when to release it. The “release” knob does just that. Also calibrated in milliseconds, a faster release time will cause the compressor to follow the signal closely so that rapid input changes (ratio) will not be lost during compression. Slower release times smooth out the overall compression effect. The dynamic process of compression will reduce signal level. As a result, many manufacturers add a gain control to their compressors in order to add back level.
Making It Work
Now that we have a pretty good idea about what a compressor does and how to operate it, I would like to share some of my settings with you. If I am compressing an exuberant preacher, I will set my attack time to fast, my release at medium and ratio from 4:1 to 5:1. For my singers, I set my attack time to medium, release to medium and ratio from 2:1 to 4:1. Should I have an acoustic guitar, I will set my attack to medium, release to medium and ratio from 3:1 to 4:1. If I’ve got a bass guitar, I will attack the signal fast and release it fast at a ratio of 4:1 to 6:1. Kick and snare drums will be attacked and released fast at a 4:1 ratio. Should I have a lively brass section, attack and release times are set to fast at a ratio of 5:1 to 7:1.
This should give you some actual settings that you can use when compressing your preachers, singers or instruments in your house of worship. Lastly, be sure to connect your compressor through your channel inserts if you are working on one particular audio signal. Or take your main mixer left and right outputs and connect them directly into the inputs of your compressor to compress the entire mix. Next month, we will look into some other outboard gear. Until then, have fun…
You can e-mail Jamie at jrio@fohonline.com.
