[ricardojoa]

Hi,
i got a question on peq equalizers. As i understand peq allows a cut or boost of frequencies in a narrow and wide Q. My question is, if the frenqurncy being cut ot boost had a wide Q, does that mean that frequencies above and below the set frequency gets affected as well?

[Davey]

Hi,
i got a question on peq equalizers. As i understand peq allows a cut or boost of frequencies in a narrow and wide Q. My question is, if the frequency being cut or boost had a wide Q, does that mean that frequencies above and below the set frequency gets affected as well?

You bet they do.  Parametric equalization is well explained on numerous websites.  Here's a nice, simple example:

http://www.rane.com/pdf/ranenotes/Bandwidth_in_Octaves_vs_Q_in_Bandpass_Filters.pdf

Dave.

[ricardojoa]

Thank you for the link. 

[Russtafarian]

Q is what makes PEQ's so tunable and powerful. 

Let's say the system sounds a bit zippy.   You could fix this by turning down the treble control (usually a shelf filter @ 10khz).  But that would diminish the sparkle and air in the system as well. 

With a PEQ, you can cut by about 6 db then sweep the frequency control to find where the zip diminishes (somewhere between 6 and 10khz).  Then you can use the Q control to narrow the filter enough to tame the zip while preserving the top end sparkle.

Say the next record you play is a 45 rpm Pet Shop Boys dance club remix with so much grating treble energy the local pets flee the neighborhood.  By temporarily widening the Q of your zip filter, the record becomes somewhat listenable through your diamond beryllium magnesium dome-ribbon hybrid tweeter.

[andy_c]

Hi,
i got a question on peq equalizers. As i understand peq allows a cut or boost of frequencies in a narrow and wide Q. My question is, if the frenqurncy being cut ot boost had a wide Q, does that mean that frequencies above and below the set frequency gets affected as well?

Yes they do.

Here's an example of the response of a parametric EQ when Q is varied. I've chosen the round number of 10 dB for the boost and 100 Hz for the center frequency, and plotted the results from 10 Hz to 1000 Hz on a log scale. I've varied the Q in a 1, 2, 5 sequence as follows:
Q = (0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0)

The smallest value of Q gives the "fattest" curve, while the largest value is the "spikyest". So you can consider Q to be the "spikyness factor". You can see that the boost area is quite "fat" for low values of Q and becomes much narrower for larger Q values.

Notice also that many of these Q values are way too low to be useful for EQ. They are for demonstration purposes only.