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Do I really need that steering wheel on my car, or can I just buy it later? This is the second discussion on sound system operation.

It seems like a silly question, doesn't it? Do you have a 31-band graphic equalizer in your sound system? If you don't, I am certain that you are unhappy with your sound. Additionally, if you do have one and it's not properly set, I am equally certain that your sound is not what it should be.

In this article we are going to explain what a 1/3 octave EQ is, and what it does. The need for it will become obvious. It is LITERALLY the steering wheel on your audio system. (Please bear in mind the EQ is only one of several audio management components that are frequently utilized, so we'll limit this discussion to EQ, as it is probably the most crucial.)

When you listen to sound directly from the source, without a sound system, it is perfect unto itself. It is what it is. Many times when we put sound through a system, the resultant sound isn't represented at all like the original sound. The sound may be thick or thin, hollow or piercing, and feedback and lingering overtones can drive you crazy. (Those of you without equalizers are now nodding your heads emphatically in agreement).

Every acoustic environment will affect the sound that emanates from your speakers, and in many cases the speakers themselves are coloring the sound as well. Cup your hands, closed, in front of your mouth and say "Hi...how are you today?" It sounds awful, doesn't it? We call this a lack of transparency. Now remove your hands from in front of your face and say it again. It sounds exactly like you, doesn't it? We call this perfect transparency, and that is what we attempt to achieve with the use of an equalizer. I say "attempt" because perfection is almost always unattainable, but we can get very close.

Now let's talk about rooms. Every room in America is built of pretty much the same types of construction materials. We all tend to use concrete and brick, gypboard and glass, carpet and tile, wood and draperies -- you get the idea. All frequencies that are put out by your speakers are reflected or absorbed to a certain degree by these materials. The frequencies that are reflected back, rather than absorbed, usually cause the most problems.

The frequencies that are reflected back to the microphone get picked up by the mic and go through the system again and again, either creating uncontrollable feedback or annoying lingering overtones. With the use of a 31-band equalizer, we can reduce the amount of sound at very specific frequencies and totally eliminate feedback and lingering overtones. Furthermore, we can "tune" in response to the acoustic environment so the system produces a product that is as transparent and natural as possible.

NOW THIS IS WHERE YOU SAY "OH SURE. RIGHT. I'M NOT AN ENGINEER, AND I CAN'T DO THAT."

How wrong you are! This isn't rocket science, and in the next few paragraphs, I'm going to prove it to you. If you have an EQ, you'll be able to tune your room and your listeners with be amazed and think you're a wizard. You don't have to tell them otherwise...let them think it!

Here's how it works:

Place all your mics on stage at the approximate locations where they will be used. Make certain they are completely behind the speakers (live mics don't belong in the live sound field).
Turn the Main Master and Monitor Master all the way off on your mixer.
Place all tone controls for each mic channel at the 12:00 position (no boost or cut), and place all 31 band EQ faders in the center position.
For now, leave the input gains and the channel faders where you had them. If you haven't read the mixer setup instructions from my first piece about mixer setup and operation, you need to do that first because proper input gain is an important factor here.
Kick everyone out of the room or tell them you are going to turn on the system and intentionally cause feedback. If they are going to stay in the room, they have to be absolutely quite for ½ hour so you can do your job.
Slowly and gently , turn up the mixer Main Master until you just begin to hear the first feedback frequency. Listen to it and try to remember it. Hum it gently to yourself. Now back the Main Master down until the feedback frequency JUST DISAPPEARS. You are now going to go to the 31 band EQ, select the frequency that you think is causing the problem.

"HOLD IT RIGHT THERE!!!" (YOU SAY). "HOW AM I SUPPOSED TO KNOW THAT!!!?????"

...TIME FOR A MINOR SIDE TRIP...

Remember the comment about construction materials? It's real. Most low feedback is going to occur around 100hz to 160hz. Most low mid problems are going to be around 400hz to 800hz, most upper mid problems are going to be 1khz to 2khz, and most high problems are going to occur between 3.15khz and 6.5khz.

100hz sounds like the boom truck that drives through your neighborhood late on Saturday night shaking the foundations.

400hz sounds like somebody playing the lowest note on a flute while they're trapped inside a cardboard refrigerator box. (Flute players hate playing inside cardboard boxes).

Pinch your nose tightly shut and, in your best 10-year-old-kid-voice, say "Doesn't this sound awful?" That's 1khz. It sounds like you're inside a soup can.

4khz is a piece of cake. It's the shrill feedback you hear when some unsuspecting public speaker steps smack dab in front of the speaker while holding the mic up to speak. It's very hard on the ears and can blow drivers in a matter of seconds. You know the one.

...OK, NOW BACK TO SELECTING THE FREQUENCY THAT IS CAUSING THE PROBLEM...

On the EQ, select the frequency that you think is causing the problem and move it UP very slightly. Remember, we were right on the edge of feedback. By moving it up, the feedback should INSTANTLY reappear, indicating you have the selected the proper frequency. If so, immediately reduce it to the -6 db point. If not, return it to the center and try another until you have found the correct frequency and reduce it. Move the frequency controls immediately to the right and immediately to the left to the -3 db point. You should now have a little V shape on those frequencies.
Return to your Main Master and gently coax it up again. If the same feedback reappears, go back and cut more at the frequency you just reduced. If a NEW feedback frequency appears, repeat the same locating process. Do this about 5 or 6 times until you can get the system Master Output fader to about plus 3 above your normal operating volume. When you drop back to your normal operating volume, feedback should not be happening.
Step to the mic and talk or sing, and listen. When you stop, are there lingering overtones? If not, great. Many good rooms won't. If so, then guess where those overtones are on the EQ, and selectively reduce those frequencies until the overtones are also gone. This guessing game of frequency location will take a bit of time on the first attempt, but you will be amazed at your own ability to differentiate if you just give it a try.
Lastly, try "tuning" the room. When you speak or sing, does it sound natural? If it does, pat yourself on the back for a job well done. If not, ask yourself if it's too boomy, if it sounds muddy, if it sounds nasal, or if it sounds brittle. If it's boomy, reduce 160hz by -3db. If it's muddy, reduce 400-630hz by -3db. If it's nasal, reduce 1.6k by -3db. If it's brittle, reduce 6.3k by -3db. Please remember that these are close ballparks. If you don't get the sound you want, try adjacent frequencies and make your decisions BASED ON WHAT YOU HEAR, NOT WHAT I SUGGEST. Your ears are unbelievably capable instruments. Use them and trust them.

You have now created a very natural sound in your system, and haven't even started to use your tone controls on the channels. If the sound coming into the channel is good quality, chances are good you won't even have to touch the tone controls on the channel strips. If the sound coming into the channel is in need of a bit of adjusting, your tone controls will be very functional in contouring the sound for each individual channel.

Incidentally, if you are using monitors, you follow the exact same procedure for them. Shut off the Main Master and use the Monitor Master and monitor EQ following the same guidelines.

If you always perform in the same room, you can do this once and then leave it alone. If you perform in different rooms every weekend, you'll have to wipe the slate clean and start the entire process over in each new performance venue. Don't worry. You'll get very fast at the process.

Finally, if you don't have a 31-band EQ, you probably want to obtain one. I don't recommend driving without benefit of a steering wheel.

I hope that this information will help you to experience vastly improved sound in your system.

As always, you can contact me at This e-mail address is being protected from spambots. You need JavaScript enabled to view it with any questions you might have. I'll be delighted to help.

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