Equalizers have been seen a lot in car audio headunits and home audio setups. They both serve the same function; to adjust and enhance the strength of the frequencies in the signal running through it. Most individuals are familiar with bass and treble controls from stock car stereo systems. These are simple equalizers and in no way unleash the full potential of your music. The two main equalizers are known as Parametric and Graphic and they both have different ways of functioning and tweaking your sounds.
Graphic Equalizers- Clarion EQS746
The most common type of equalizer is the graphic EQ which is composed of a row of sliders that are pushed up or down to boost (raise dB) or cut (lower dB) bands of frequencies. You will find these equalizers as physical sliders, knobs or in a digital format found on most aftermarket car stereos. Graphic equalizers will have a number of bands, or frequencies, that it can boost or cut. For example, a seven band graphic EQ like the Clarion EQS746 can boost or cut 7 fixed frequencies which are 50Hz (bass), 125Hz (mid-bass), 315Hz (upper midbass), 750Hz (lower midrange), 2.2kHz (midrange), 6kHz (upper midrange) and 16kHz (treble or high-frequency). The frequency can be boosted or cut by a range of +/- 12dB for this EQ but could be different for other equalizers.
So, what about all of the other frequencies, are they left out from getting a boost or cut? The Graphic EQ drags frequencies along with it, for example if you take 125Hz and cut it, the surrounding frequencies will cut with it in a slope pattern. The farther the frequency is away from the frequency being cut, the less it is cut. This might seem preposterous to some, but with 20,000 frequencies available, a 20,000 band EQ is not practical. Essentially, graphic EQs have fixed center frequencies (ex 125Hz), fixed bandwidth (frequency range the boost/cut will effect), and adjustable level (boost/cut in dB). What if you want to cut 100Hz and ONLY 100Hz? Say hello to the Parametric EQ.
The Parametric EQ is technically a different tool all together and best used after tweaking your graphic equalizer. The objective of this EQ is to shape the sound very precisely at each frequency by adjusting the level (boost/cut), the center (fixed) frequency and the bandwidth (Q) of each frequency. Think of Parametric EQs as the surgical work when it comes to frequencies. 315Hz is your culprit and seems too loud giving you a weird musical response so you cut the 315Hz fixed frequency and only that frequency. This won’t affect the surrounding frequencies like the graphic EQ does. It still sounds bad however, so you decide to up the bandwidth (Q) and bring a few other frequencies near 315HZ down as well. So, from 300Hz to 330Hz all of those frequencies will be cut in a sloping pattern, with the 300Hz and 330Hz receiving the least amount of cut.
To wrap it up, a graphic EQ gives you the quick and dirty frequency adjustments while a parametric EQ lets you go in with surgical precision and finish the job. Get a parametric equalizer and fiddle around with it, you may be surprised at the kind of music quality you can achieve.