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[john11]

Hi and thanks for reading this post.

Not too sure what q means in the parametric eq.

I have the frequency set at 20khz, the q is set at default which is 1

Which frequencies will be boosted with these values

Also what is the max boost allowed, most eq's i have used are + or - 12db

Many thanks. John.

[mattkhan]

Q is just a measure of the bandwidth of the filter; the lower the Q, the wider the frequency range it has an impact on. Put another way; higher Q is a notch filter, lower Q is more like a tone control.

A Q of 1 would normally mean the -3dB points will be about 1.4 octaves wide so at 20kHz this is a range of ~12kHz to 32.5kHz (more precisely the range would be 20000/(2^0.7) to 20000*(2^0.7) Hz). I think you need to be upsampling to a higher sample rate for it to actually have that effect though, not 100% what happens to the shape of the filter if it is curtailed by nyquist (1/2 sample rate).

You can find a calculator/description here http://www.rane.com/note170.html and a graphical calculator in http://www.earlevel.com/main/2013/10/13/biquad-calculator-v2/ (choose the peaking option)

[sorepinky]

As an example, I used REW (Room EQ Wizard) to measure my in-room response from the favourite seat and it determined a couple of filters to flatten the modal region response a bit, those being -9dB at 40 Hz and -2.5dB at 110 Hz.  Both Q=3.  With these typed in to DSP Studio's Parametric EQ section I tested to see what MC does to a REW sweep by setting the JRiver WDM as the default Windows audio device.  Here is the result showing both the magnitude and phase responses with the two filters in place:



Cheers.

[john11]

Hi. Thanks for the replies,much appreciated.

I decided on a q of 7 not sure why sounds better maybe different. Which frequencies will this affect if q is 7 and frequency boosted is 20khz.

Also what is the max boost allowed, most eq's i have used are + or - 12db

Many thanks.

[sorepinky]

Why would you want a sharp boost around 20kHz anyway?  Most people can't even hear that high.  You could blow your tweeters for nothing.

[jjazdk]

You didn't even bother trying out the links mattkhan gave you?

The biquad calculator shows you what happens when you apply a 20kHz boost with a Q=7.

But... such a filter doesn't make any sense at all, which you should be aware of if you want to play with high Q filters.

Hi. Thanks for the replies,much appreciated.

I decided on a q of 7 not sure why sounds better maybe different. Which frequencies will this affect if q is 7 and frequency boosted is 20khz.

Also what is the max boost allowed, most eq's i have used are + or - 12db

Many thanks.

[john11]

Hi. Thanks for the replies.

Even though your words of wisdom are invaluable to me it does not explain what the max boost allowed is

Most eq's are + or - 12 db

Why is a q setting of 7 nonsensical?

Thank you.

[mattkhan]

A high frequency notch filter is an unusual thing for sure.

I am not aware of a limit to the magnitude of the filter, make it as big as you like

[jjazdk]

There is no such thing as a max boost, it all depends on the actual application, but... keep in mind that for every 3dB you are doubling the power, so a 12dB boost requires 16 times more power!

A Q=7 is not in itself nonsensical. But a boost at f=20kHz with Q=7 does not make any sense, just look at what it does in the frequency domain, why would you ever want to apply such a narrow band boost at 20kHz?

Generally speaking, it is not advisable to correct very narrow (high Q) dips, but it is perfectly okay to dampen peaks. Also, our ears are a lot more sensitive to peaks than dips.

Hi. Thanks for the replies.

Even though your words of wisdom are invaluable to me it does not explain what the max boost allowed is

Most eq's are + or - 12 db

Why is a q setting of 7 nonsensical?

Thank you.