Sound Ministry Series Part 4 - The High Frequency EQ Knob

The first knob you encounter in the EQ section of your channel strip will be the High Frequency knob (sometimes labelled "HF").

This knob boosts or cuts all frequencies above 12kHz (which in note terms is the F# in the 9th octave of the piano).

This control can be used to remove excessive 'essing' or brittle-ness from a vocal, or it can be used to add clarity and sparkle to instruments and 'airiness' vocals. If you are micing a drum kit, use it to add shimmer and brilliance to your cymbals.

12kHz is the top end of the human voice's range. This frequency would most significantly affect your soprano singer, a church organ and the cymbals of a drum kit.

Remember, as with all eq'ing, to use it gradually and sparingly. Don't just randomly turn knobs. Turn it a little, then listen carefully. Has the sound improved? Has it deteriorated? If you are making adjustments during a service, ensure that you do things so gradually that the congregation wouldn't notice you making the change.

Also bear in mind that higher frequencies are very directional (in contrast to low frequencies, which just go everywhere!). If you are making adjustments here, you need to make sure you are listening in the direct path of the speaker to hear the actual affect, or you may end up increasing too much high frequency.

For more info on eq, check out this video series: http://www.prosoundweb.com/videos/video/introduction_to_equalization/

Next time: the Midrange control knobs

Sound Ministry Series Part 3 - the PAD switch and the Low Cut filter

Your mixing desk may or may not have a PAD switch, but if it does you can use it to make very high signals easier to work with. For instance, if anything on stage has a built-in preamplifier (like a guitar effects pedal, or a specialty microphone) it may just distort when you plug it in to your desk, even with the gain and channel volume set really low. Use the PAD switch to get the level down so it is easier to control and doesn't distort.

The low cut filter (or high pass filter) is usually a button near the channel input. It essentially dampens the lower frequencies present on that channel, often from about 100Hz down. Don't use this on your kick drum, bass guitar and piano, or you will lose the low-end richness of those instruments. Do use it on all microphones and other instruments that don't produce very low sounds to eliminate traffic noise from outside, handling noise and the low frequencies from other instruments being picked up in those channels.

Next time: the high frequency EQ knob

Sound Ministry Series Part 2 - Setting Channel Gains

The "gain" control (sometimes called 'trim' or 'level') is the first control knob you encounter at the top of each channel on your mixing desk.

The purpose of this knob is to control the level of the input signal into that channel. If this control is not set correctly, you won't have adequate control over the volume of that channel when you use the fader/slider.

If the gain is set too low, the signal will be too weak and you may introduce system noise (sounds like hissing) as you turn up the channel to compensate. If it is set too high, you may introduce distortion which may damage your equipment, or the channel may feed back.

To set the channel gain is quite easy. Use the "Solo" button (or PFL on some mixers) on channel one to display that channel's levels in the visual meter on the far right of the desk. Next, have someone speak, sing or play into that channel alone at performance levels and turn up the gain until it just peaking into the orange/yellow. If it goes into the red, you are too high. If it stays in the bottom green, then ensure that the -20dB "PAD" switch is not pressed in on that channel.

Repeat for all channels. Remember to keep the volume low (or better, off) for this exercise.

Done! Now our channel gains are set. This will give you the best signal to work with, and if gains are correctly set it will be easier to balance your mix across the channels, because each fader will respond similarly to your adjustments.

Note: Mics will require large amounts of gain, so don't be surprised if you end up in the >75% range. Instruments will usually require less gain, especially if you are using DI boxes.

Next time: the PAD switch and the Low Cut filter.

Sound Ministry Series Part 1 - Setting Up

Before you even turn on the desk or the amp, you will need to set up. Start by plugging in everything (mics, instruments, etc.) so that you have the minimum to plug in when the system is on, which could damage the speakers. At this stage, turn on things like guitar amps and keyboards.

As you plug things in, remember to arrange things logically across the stage. It is good practice to use Ch 1 for whatever is furthest to the left of the stage, and then work across to the right from there, moving up the channels. Write down what (and who) is in each channel for easy reference. This way, the desk visually mirrors what is on the stage.

When everything is plugged in, turn on your desk first, and then your amplifier. This avoids the "bang!" of turning on the desk after the amp is on, which could damage the speakers.

As you approach the desk, never assume that the last mix is still applicable. If you have the luxury of time, this would be a good time to turn down all the faders and gains and zero the eq's.

Next time: Setting Channel Gains

Sound Ministry Series

After an amazing and encouraging workshop this last Saturday, I thought it would be helpful to start a series on the basics of sound operation. Very often, the guys behind the desk do what they can very willingly, but are not confident in their knowledge of the whole picture.

This series of short posts will start at the beginning and go through the stages of setting up and mixing for a Sunday service. God-willing, it will add confidence to what you are doing, expand your knowledge and help you serve the body of Christ better.

Lastly, thanks you so much for your valuable ministry!