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Changing High-pass Q - Not Working

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Wed, 06/27/2018
5:49pm
Dave Ernst
#1
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#1
Changing High-pass Q - Not Working

Hi,

I'm using a second order butterworth high-pass filter within a Second Order Filter Cascade. I would like to increase the Q of the filter but changing the value does not appear to actually change anything.

I'm using AWE Standard 6.17.05 at the moment.

I appreciate your advice. Thanks!

Wed, 06/27/2018
6:51pm
Axel Nilsson
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Hi Dave,

 

By definition, a Butterworth filter has a constant Q of 1/sqrt(2) (~.707). This means that in the inspector of the Second Order Filter Cascade module, the Q factor is actually decoupled from the module when the filter type is Butterworth. 

 

If you want to change the Q factor for a second order HPF, there is the VariableQHPF choice at the bottom of the filterType dropdown list that will meet your needs. You'll see that if you set the Q to .707 with this filterType, you'll have the same frequency response as your Butterworth filter. 

 

Hope this helps you out,

Thanks

-Axel

Thu, 06/28/2018
8:42am
Dave Ernst
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(Reply to #2)

Hi Axel,

Thanks for the support.

I realized that the VariableQHPF was not an option in AWE 6.17.05 but it is in the latest version. I'll try it out.