Tips for using equalization to truly improve your soundWhenever I think of an equalizer it brings back fond memories of the Edward Woodward TV show. GOT A PROBLEM? ODDS AGAINST YOU? CALL THE EQUALIZER! In many senses, that inviting collection of sliders in your rack serves much the same purpose. It’s job is to eliminate problems and put the odds back in your favor.
All Things Being Equal…
The primary purpose of an equalizer is to do just that, “equalize.” Make things equal. There are a number of things that are “not equal” in sound. When we say equal, we’re referring to the reproduction and perception of a full spectrum of sound. For example, if we pass 31 equal bands of pink noise through a system, those 31 frequencies will be reproduced at different levels. Some louder, some quieter. This is due to the frequency response of your loudspeakers and other in-line equipment; they simply cannot reproduce sound that’s truly flat. On top of this, every room presents a different acoustic environment for your loudspeakers. Some frequencies are absorbed while others resonate. Call me a geek, but one of my favorite things to do is to use a tone generator to sweep frequencies in a room and listen for things to start resonating. Without adjusting the amplitude, certain frequencies will seem noticeably louder as you sweep through them.
We want to use our EQ to flatten these frequencies out to account for the speakers and the room. Remember, it is always better to cut rather than boost. Be very careful when pushing your EQ into positive dBs. Once we have achieved a flat state, we can begin to “color” or “flavor” the sound to suit us. Most people don’t like a truly flat sound, even though it’s acoustically the most accurate reproduction of what was input into the system. A friend of mine who is an engineer at a loudspeaker company we all know and love has a perfectly flat system in his house. Everybody asks him what is wrong with his system, even though it is technically perfect.
Identifying the response of a system can be made much simpler with the use of a Real Time Analyzer. An RTA will often both generate the pink noise or other specific tones into your system (mine, via an XLR jack on the unit) and then measure the response (again, either via XLR or a built-in mic on the unit). This will then display the system’s response on the screen as well as recommended EQ settings. This provides a good baseline to start with. Often RTAs have several utility features such as polarity checker, decibels (with a few weighting options to choose from), and a few other neat tools. Mine also has the ability to connect to a computer’s USB port so the information can be further analyzed, stored and utilized.
DSPlay of Power
In these modern times, our lives have been made substantially easier by DSPs (Digital Signal Processors). These devices offer greater processing power than a typical analog EQ, in less space. They offer us options such as parametric EQs and easier-to-digest graphic displays of what our signal is doing. Many even connect to a computer for larger, color displays and easier manipulation of the sound. Perhaps one of the most useful features is the ability to have EQ settings for your loudspeakers (which are a constant) and separate EQ settings for the room (which vary). These settings can often be stored in multiple presets. For example, you may use different loudspeakers, or use your system in different ways; perhaps a full range system for smaller shows, and a 2-way system with subs for larger gigs or school dances. You could easily recall these EQ presets, and in some cases, also recall crossover settings and other relevant system settings. Additionally you could store a number of frequent venues that you play, thus allowing you to have optimal sound time and time again with just the push of a button.
Another tremendously useful purpose for EQs is eliminating feedback. Feedback is a “loop” generated in your system when the system “hears” itself and reproduces that sound it hears. This often just involves a few problem frequencies, again due to the response of the loudspeakers, characteristics of the room, and the response of the microphone. In live sound rigs you’ll many times find an outboard EQ inserted into the mic channels allowing for individual EQ adjustments for each mic. More practical, however, for your system is likely to be the reduction of offending frequencies with regard to your mic and your loudspeakers. Most DSPs have some type of “feedback suppression.” This is basically an EQ that senses for a boost in a specific frequency and then reduces it in a very narrow notch. It’s very handy, but the same results can be had with a good old-fashioned analog 31-band EQ in the right hands.
Any time you cut or reduce a frequency, you reduce its presence in your audio signal. While this can have positive effects for reducing feedback, it can negatively affect your music playback quality. A simple solution to this is to set your EQ for music playback, then take the wireless mic that you will use for toasts, cake cutting and other speech applications where there will be limited or no substantial music playback, out and about and re-EQ for feedback suppression. Make a note of your EQ settings prior to making these adjustments; after the speeches are over, reset your EQ for music playback.
Keep in mind that you are likely to have fewer feedback problems than your guests will when using the same mic, because as a professional you should have good mic etiquette. Here much can be done to ease the burden on your EQ by simply using a mic properly: not talking off-axis, not keeping it at an unreasonable distance from the source (your mouth), etc. Even the best equipment will be compromised by improper use.
Resist the Urge to Smile
The most common “one size fits all” use we see of EQs is the smiley face. Boosted lows, flat mids and boosted highs. It has been long debated why we resort to this kind of behavior. Bad genetics? Some will say that it’s because of the decrease in sensitivity we have at those frequencies, while others point to a loudspeaker’s data sheet and show its reduced response at the highs and lows. Yet others feel they are adding “boom and sparkle” to their music. Likely it isn’t too effective, as you’re applying a generic response to your system and room without any real regard to what the speaker is capable of reproducing, or, for that matter, where your “boom” comes from. You may just add mud to the bottom end. Use your EQ properly and listen to your system come alive. The next time you go to a concert or club and hear a system that sound fantastic (punchy midbass, deep lows, clarity and definition in the harmonics and ambiance) go check the EQ. I know you want to look at the rack anyway. See if it’s smiling at you. Chances are, it’s not.
Ben Stowe began his love of electronics at the age of 3, growing up in a TV repair shop. He began his role with NorthernLightFX (www.northernlightfx.com) 15 years ago, and continues his leadership of the company today. Ben shares his passion for technology through a number of company-sponsored educational efforts designed to help end users get the most out of their equipment. He holds a Minnesota electrical license, an InfoComm CTS and numerous other certifications. Ben can be contacted via firstname.lastname@example.org.
Filed Under: Issues from 2008, Sound
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