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TYPES OF EQUALIZERS
Writen By : Edmund Jude
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An Equalizer is a device that is used to control the harmonic/timbral content of a sound or signal. Equalization is the alteration of the levels of different frequencies so that the levels of certain frequencies are more or less pronounced than the others
Below are the types of Equalizers:
1)Common Tone Control
2)Sweep EQ
3)Parametric EQ
4)Graphic EQ
5)Paragrahic EQ
6)High Pass Filters
7)Low Pass Filters
A) COMMON TONE CONTROLS / SHELVING EQ
The tone controls on a Hifi or car stereo is a form of an equalizer. It operates on 2 bands BASS(low freq) and TREBLE(high freq).
When you turn up the bass control, you are increasing the low freqencies . This creates a richer or fuller sound. If boosted extremely , a boomy sound.
When you turn down the bass control, you are reducing the low frequencies resulting in a thinner or tin like sound.
COMMON TONE CONTROLS ARE ALSO KNOWN AS SHELVING EQ
B) SWEEP EQ
The Sweep EQ is much like the earlier mentioned EQ except that the frequency can be selected and then cut or boosted.
Sweep EQ's have two knobs for each band of frequencies, A Frequency Select knob and a cut/boost knob.
C) PARAMETRIC EQ
The Parametric EQ has an additional feature called the "Q". The "Q" is a feature which controls the broadness or sharpness of the frequency curve. The higher the value of "Q", The sharper the curve. "Q" settings are normally between 0.5 to 5
Parametric EQ's have three controls which are
1)CENTER FREQUENCY
2)CUT/BOOST
3)"Q"
One of the benefits of using parametric equalizers is that the frequency can be precisely selected, and the "Q" adjusted so that a minimal cut/boost can be applied to a particular frequency. The adjacent frequencies where correction is not needed will not be affected.
D) GRAPHIC EQ
A Graphic EQ is a multi frequency band pass/reject filter. Unlike typical 3 or 4 band EQ,
the Graphic EQ can operate on 8 or more Freqency Bands.
The unit is called Graphic EQ because most of them have linear slider controls. When you see them, they create a visual image that resembles the overall frequency response curve.
Commonly used Graphic EQ's in live sound setups are the 31 band Graphic EQ which has it frequency start at 20hz and goes all the way till 16kHz or even 20kHz
E) PARAGRAPHIC EQ
The term Paragraphic Eq is derived from the combination of Parametric and Graphic EQ. It
is a graphic Eq with a sweepable center frequency instead of having a fixed band center frequency.
A Paragraphic Eq is generally used for tuning out feedback , It functions like a Graphic Eq but with an advantage of sweeping the center frequency to an exact point where feedback occurs, thus allowing minimal cut to be applied.
F) HIGH PASS FILTER
A High Pass Filter Allows all frequencies above its cut off point to pass through. Frequencies below its cut off point gets attenuated.
The cut off point is the frequency at which the signal starts being attenuated. The rate at which this attenuation occurs is defined by dB per octave.
EXAMPLE OF HIGH PASS FILTER USAGE:
A Low frequency of between 5-30 hertz may be generated by footsteps along the stage floor and can get picked up by a microphone through vibrations in the mic stand and travel to the console then into the amplifiers and finally to the speakers.
These frequencies of between 5-30 Hz will not be produced by most speakers but will use up a lot of amplifier power (This may cause distortion or probably failure of the amplifier)
Using a High Pass Filter in this situation will eliminate the chances of the 5-30 Hz frequencies from entering the Amplifier .
G) LOW PASS FILTER
A Low Pass Filter attenuates frequencies above a certain cutoff point. They are normally used to cut off unnecessary portions of the audio spectrum (example: hiss and noise)
Instead of creating distortion with higher frequencies which may not be accurately reproduced by your audio system. It will be better to cut off the higher frequencies with a Low Pass Filter
This article has been writen by Edmund Jude . For Further Enquiries or suggestions regarding this topic CONTACT WRITER VIA EMAIL
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