class:: BLowShelf
summary:: Low Shelf
categories:: UGens>Filters>BEQSuite
related:: Classes/SOS, Classes/BLowPass, Classes/BLowPass4, Classes/BHiPass, Classes/BHiPass4, Classes/BPeakEQ, Classes/BHiShelf, Classes/BBandPass, Classes/BBandStop, Classes/BAllPass

description::
The B equalization suite is based on the Second Order Section (link::Classes/SOS::) biquad UGen.

note::
Biquad coefficient calculations imply certain amount of CPU overhead. These plugin UGens contain optimizations such that the coefficients get updated only when there has been a change to one of the filter's parameters. This can cause spikes in CPU performance and should be considered when using several of these units.
::

classmethods::

method:: ar
argument:: in
input signal to be processed.
argument:: freq
center frequency.
WARNING: due to the nature of its implementation frequency values close to 0 may cause glitches and/or extremely loud audio artifacts!
argument:: rs
the reciprocal of S. Shell boost/cut slope. When S = 1, the shelf slope is as steep as it can be and remain monotonically increasing or decreasing gain with frequency. The shelf slope, in dB/octave, remains proportional to S for all other values for a fixed code::freq/SampleRate.ir:: and code::db::.
argument:: db
gain. boost/cut the center frequency in dBs.
argument:: mul
argument:: add

examples::
code::
s.boot;
(
z = { // toy around with boost/cut
BLowShelf.ar(
	SoundIn.ar([0,1]),
	MouseX.kr(40, 6000, \exponential),
	1.0, // rs
	MouseY.kr(24.0, -24.0, \linear),
	0.5); // mul
}.play)
z.release;

(
z = { // toy around with rs
BLowShelf.ar(
	SoundIn.ar([0,1]),
	MouseX.kr(20, 6000, \exponential),
	MouseY.kr(0.1, 1.0, \linear), // rs
	6,
	0.5); // mul
}.play)
z.release;
::