Two completely different topics—I know. Stay with me. I am writing this from an undisclosed location near Nashville. My family and I are here for a wedding of a dear friend of mine, Zach (of Zach and Sarah fame from John and Sherry in the morning on K-Love if you hear that where you live...). It's really fun because I haven't seen Zach in some time and he is one of the first people I ever trained in audio. Last night I was invited to his impromptu "Bachelor Party." I have to tell you it was great to sit around with his peers and hear how much of an impact he has had on their lives. I thought back to 15 years ago when I was leading the youth group and he and I had so many deep discussions about theology and leadership. I was reminded of the verse, "Know that your labor in the Lord is not in vain." What a joy to see how God used what I had to give years ago to now be such a blessing in others lives. Zach is truly one of the "good guys," and it is truly an honor to know him. Zach, I wish you and Sarah all the very best God has in store for you.
I write this not only to indulge my sense of nostalgia, but also to encourage you, dear reader, to continue to invest in the lives of others. At times it may not seem like it makes a difference, but when we give of ourselves to others in the name of Christ, it does not return void. God will use even our most feeble efforts to accomplish His goal. What a privilege to be part of that.
Now on to our topic at hand—Pastors (OK, speakers) and compressors. I'm not speaking of a magical device that will shorten a 40 minute message to 30, rather the magical device that keeps the level of the speaker's voice under control.
I'm a firm believer in compressing the spoken word. If I have enough channels of compression, I will compress everyone on stage who talks. I do this for two reasons; to make sure that the voice levels are high enough so that everyone can hear every word and to keep the listeners from becoming fatigued. Let's tackle one at a time.
First, compression will help ensure the level of the speaker is sufficient to get over all the other noise in the room. It's seems counter-intuitive that a device that lowers gain will help you keep levels up, but work with me.
Pretty much any room will be noisy, even when it's "quiet." People rustling papers, coughing, HVAC noise, babies crying; all of these things (and more) add to the noise floor of the room. In order to make sure the pastor can be heard, we need to keep the level above the noise floor. Placing a compressor on the insert of that channel gives us the ability to keep the average level up while not allowing peaks to get too loud. The compressor keeps the level more consistent, and more listenable. It's not possible for a sound tech, no matter how good, to "ride" the level of a speaker and keep it smooth. The compressor does it more quickly and more consistently while the sound tech can keep an eye on the big picture.
You see, the challenge of putting the voice through a system capable of generating ear splitting levels is that the voice can easily get so loud that it hurts. In our room for example, we have a few speakers who can easily fill the room with just their voice, especially when they are making an enthusiastic point. All of those dynamics add up to listener fatigue when run through the sound system. The speaker gets so loud that it is plain uncomfortable to listen to. What I try to do is keep the speaker's voice supported with the sound system when he (or she) is speaking quietly, and let their natural voice do the work when speaking loudly. The compressor allows this to happen smoothly and (if set correctly) transparently.
So how do we set it up? It varies a little from speaker to speaker, but I like to put the compressor on the channel insert for their mic. After I set the gain on their mic, I will start with a mild ratio of 3:1-4:1, and start lowering the threshold of compression until I get between 2-4 dB of gain reduction. This "leveling of the peaks," is enough to lower the overall dynamic range and make it more easy to listen to. When loud passages come along, or if I'm dealing with a more dynamic speaker, I like to let the compressor take out enough so that the increase in energy is apparent, but doesn't result in the hair of the audience being blown back. Sometimes this means 6-9 dB of gain reduction. If you get into too much more than that, it will start to sound unnatural. Keep in mind, gain reduction of that magnitude is for brief periods of time, as in a word or two. You don't want to run a steady state of 6-9 dB reduction.
I may accomplish this by lowering the threshold, or by increasing the ratio. If a speaker is mostly steady state, with occasional flashes of energy, a higher threshold with a higher (5:1-6:1) ratio may keep those loud moments under control. There is definitely some experimentation to be done here.
As for attack and release times, I will often just use the "auto" setting on the DBX 166XL I use for this. If you aren't happy with that, or don't have a good auto setting, try 30 milliseconds of attack and 100 ms of release. This may or may not work for your speaker, but it's a good starting point. You want to keep the release time short enough that a loud word doesn't kill the volume of the next sentence.
One thing to be aware of is that you want to set the gain on the channel with no compression or gain reduction (or gain increase on the compressor). Either pull the insert out, or set the output at 0 and raise the threshold all the way up (on the compressor) while you set the gain (on the board). The danger is that if you set gain with the compressor active, you can end up overloading the pre-amp while still seeing 0 dB on the channel. The compressor will just compress whatever you send it, lowering the volume back to the channel, meanwhile you can have the gain on the board cranked into nasty distortion zone. So be aware of that. If you see red clipping lights flashing even though your level appears in the green, that's what's happening.
I also recommend that if you are not familiar with compression that you do some experimenting at a time that is not the service. In fact that's a good rule of thumb: Don't try out new technology or settings during the service (don't ask me how I know this).
So there you go—a brief (yeah right!) tutorial on compression. Happy mixing!