6. X-EQ Filter Types
6.1 Bell Filters
Q Definitions
P – 3dB – Classical definition that means Q is measured 3dB below peak for boost or 3dB above peak for cut.
0 – 3dB – Definition used for bells in some US products, the bandwidth for Q calculation is measured 3dB below 0dB line for cut or 3dB above for boost. Q in both definitions correct only for +6dB boost/cut.
P/2 – New “musical” definition based on the bandwidth measurement in the middle of a bell filter, between peak and 0dB line. Normalisation – All 12 equalisers are normalised to have exactly the same bell shape for +6dB boost.
Classic Symmetrical
The m ost po pular p arametric EQ shape used i n various mi xing consoles and outboard gear. Almost constant Q characteristic.
P – 3dB
Asymmetrical | Classic |
Often features in older equalisers. Boost as above but much |
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narrower cut characteristic. |
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P – 3dB boost |
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0 – 3dB (x2) cut |
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