4.5 Parallel Passive EQ | |
Parallel E Q exhibits quite different sonic properti es to t he | |
familiar serial | parametric EQ. We are generall y used to |
hearing the effect of one EQ band superimposed on another, | |
as opposed to the band interaction inherent to a parallel EQ. | |
Because the bands are placed ina parallel configuration, phase | |
cancellations and | |
obvious when first encountered. | |
Passive EQ is something that is found in old equaliser units | |
and is generally known for its transparent and natural sound, | |
but has some problems associated wi th it. However, in the | |
digital domain | these shortcomi ngs do not have such an |
influence. |
|
A passive EQ does not have a ny gain elements, but can still have controls to seemingly boost frequencies as well as cut. What actually happens is that the entire signal i s cut by a n amount, but the frequencies which are apparently ‘boosted’ are simply not cut as much. Therefore the unit must attenuate either the input, the output, or both to allow enough headroom. Unfortunately in the analogue dom ain, a 20dB reduction in signal lev el p roduces a 20dB increase i n the noise floor. Luckily,in the digital domain with a
In
You may find yourself entering this mode more and more as you become familiar with the sonic signature. Larger gain changes are possible without colouration, and boost starts to become something that is useable to a significant degree in a digital EQ!
Parallel EQ does however exhibit asymmetry in its boost and cut characteristics. But this is not su ch a bad thing as m ost engineers would agree that boost is best done with low (wide) Q values and cut with a higher (narrower) Q.
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