Alesis Q20 manual 35

Overview - Chapter 3

Shelving EQs

Lowpass Shelf and Highpass Shelf

A shelving EQ can boost or cut frequencies in its pass band, while allowing the frequencies outside its pass band to go through it. The shelving EQs of the Q20 provide gains from -14dB to +14dB in 0.1dB increments. Shelving filters are well suited for applications in which high or low frequencies need to be boosted or cut, but the remainder of the audio signal is to pass through unchanged. Applications for shelving EQs include removing high end hiss, and Òtightening upÓ the sound of a bass instrument. The Highpass Shelving EQ is useful to compensate for a lackluster source that needs its high end brightened. The Lowpass Shelving EQ can be set to cut low frequencies to eliminate PA rumble.

+14dB			+14dB
+11dB		Gain = +14dB	+11dB	Gain = +14dB
		(boost)		(boost)
	Cutoff				Cutoff
0dB	Frequency		0dB		Frequency
		Gain = -14dB		Gain = -14dB
-11dB		(cut)	-11dB	(cut)
-14dB			-14dB
	Lowpass Shelving EQ			Highpass Shelving EQ

Single Band EQs

1 Band Low Parametric and 1 Band High Parametric

A single band parametric EQ allows frequencies within its passband to be amplified (boosted) or attenuated (cut) while allowing the remainder of the audio information to pass through unchanged. The Q20 provides a low frequency version (20Hz to 2000Hz), and a high frequency version (1500Hz to 10kHz). Single band parametric filters work well to highlight specific frequencies in a mix; for instance, bringing a tambourine to front and center, or boosting a repetitive bass line to achieve a realistic Òinner-city throbÓ.

	Bandwidth
+14dB
+11dB		0dB
		Center Frequency
		Bandwidth
0dB		-4dB
	Center Frequency	-7dB

1 Band Parametric	1 Band Parametric
(boost w/ low bandwidth)	(cut w/ high bandwidth)

Q20 Reference Manual 33