I think it’s safe to assume we all know what a mixer is for: you use it to combine separate sound sources into one ‘lump-free’ mix. A mixer is a device that combines many audio signals into one destination signal. You take two separate audio sources, such as a microphone and an MP3 player, connect them to a mixer and all of a sudden you can combine the two sources and play them as if they are one and the same.
So let’s look at what it takes to hook a mixer to a PC and a microphone to a mixer. In its simplest form, a mixer contains inputs, or channels, to which you can connect audio sources. The cheaper the mixer, the fewer the channels (or inputs) the manufacturer will give you, and the opposite is also true. Each input has its own control, which is used to send more or less of the signal to the output of the mixer. The (stereo) output can then be fed into an amplifier or a recorder of some sort such as your computer.
How to Use an Audio Mixer with Your PC
First of all, you need to hook the mixer up to your computer. If you are one of the lucky ducks with a USB mixer, then all you have to do is find the USB port on the mixer, locate the same on the computer and connect them by using the designated cable. More than likely, you will not have a USB mixer, but don’t worry, just find the line-in jack on your computer. Typical connectors are stereo mini jacks or RCA (in which case there will be two). On your mixer, find the connectors that are labeled ‘main out ‘. On some mixers you will find a ‘tape out’. Either will work, but if you do have a ‘tape out’, it’s probably easier to find the correct cables for it, be cause ‘tape out’ connections usually use RCA cables. Even if the line-in on your PC’s soundcard uses stereo mini jacks, though, you should have little trouble finding the right cables at your local wire-farm. Just remember the rule you learned about basic shapes when you were a toddler: you can’t fit a square peg into a round hole! So find the connectors and the proper cables and just string them all together.
We know that mixers have dedicated inputs for microphones, or at least inputs that can be switched from line-level to microphone-level. There is good reason for this. Not all sound sources are created equal, and as these things go, microphones are about as ‘unequally’ created as they come. Compared with line-level sources (CD players, MP3 players, computers, and so forth), microphones put out a very, very weak signal. All microphones require extra amplification, and you can’t just ‘pump up the volume’, because you’d be pumping up the noise that a microphone generates all by itself to unbearable levels.
Microphone inputs (or channels) on a mixer have built-in pre-amplifiers. These inputs should also have another extra, a 48-volt phantom power supply. This extra power supply is there because condenser microphones need external power. Now it’s time to hook up that microphone.
Set the master volume of your mixer to 0 dB. Set the fader on the channel strip that you’re plugging the microphone into to 0 dB as well. Find the gain/trim knob for that channel (hint: it’s usually right under the XLR connector). TURN IT ALL THE WAY DOWN!
Go ahead, now plug in the microphone. And just in case you are wondering which cable to use, just remember…Square peg, round hole. After plugging in the microphone, you will have to do three things at once, but first locate the VU Meter on your mixer. It’s usually found close to the master fader and typically consists of a needle-type gauge (like the speedometer of a car) or a set of vertically placed LED lights ranging in color from green at the bottom to red at the top. The last green light will be labeled 0 dB.
Now for the three things that need done simultaneously: Look at the meter; Talk into the microphone; and turn the gain/trim knob clockwise. Keep talking and keep turning the little gain knob clockwise. As you keep talking you want to make sure that you don’t vary the distance from the microphone to your mouth too much and that you talk at a volume slightly louder than what you expect to use while recording. What you are after is a signal that peaks right around the 0 dB mark on your VU meter. (You were still watching it, weren’t you?)
You now have your mixer set so that when you speak normally, the mixer is not artificially boosting or cutting your signal. You are getting out of the mixer what goes in, more or less. You can now start playing around to your heart’s content. Turn up the volume (you will hear when it is too loud – it will sound ugly), play with the EQ, add sound effects that your mixer may have built in, turn the fader for the microphone down but push the gain/trim all the way up (to get some nice fuzz), and so forth. When you royally mess up and it sounds horrible, you now know how to get back to a basic working setting.
To Sum Up
Just one more thing…Remember the phantom power that I mentioned earlier? If none of the instructions in the last paragraph worked, and if turning up the gain/trim had no effect and you heard NOTHING, then you most likely have a condenser microphone, and you will need to look in your mixer’s instruction manual for how to turn it on!