Analog Biquad Filter and Prewarp frequency

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dspdude
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Analog Biquad Filter and Prewarp frequency

Hello

 

Is it possible to add the following biquad to the SOF block ? This is useful for creating things like Linkwitz Transform functions used to equalize seal box enclosures etc. Also is it possible to add the prewarp frequency as an optional parameter ?

Regards

David

            (s*Tz)^2 + s*Tz/Qz + 1
G(s) = Go * ----------------------
            (s*Tp)^2 + s*Tp/Qp + 1
-
where Tz=1/(2*pi*fz)  Tp=1/(2*pi*fp)
or the more general form would be handy as well
            N2*s^2 + N1*s + 1
G(s) = Go * -----------------
            D2*s^2 + D1*s + 1

 

 

 

Axel Nilsson
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Hi David,

 

I've put in a module request for your desired feature. If we see enough demand or a strong enough need for this update then we may implement it in a future version of Audio Weaver. 

 

Thanks for the request. 

-Axel

yoke
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Are there any progress with adding Linkwitz Transformer block inside audioweaver via biquad ?

(I think that now days it should be implemented as standards just like any other filter tipe and order)

 

thanks

Josip

Axel Nilsson
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Hi Josip,

 

We have not added any additional support for creating Linkwitz Transformers inside Audio Weaver. Your interest in this feature is well received however.

Though we don't have the feature built in, you can create one yourself by using our Biquad module and a few ParamSet modules. You can calculate the coefficients within your design based on desired cutoff frequency and Q (which will come from DCSource modules), and then feed each calculated coefficient into a ParamSet module, which in turn can set the actual coefficients in the Biquad module. This will allow you to have a  biquad as depicted above that is tunable during runtime with the inspectors for your frequency and Q DCSource modules. 

 

Hope this helps some.

-Axel

 

 

dspdude
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Hi Josip

This is how I approached it for one client. You need to down convert from 192KHz to 48KHz otherwise you will get round-off errors in the filter but since it is bass then 48KHz is more than adequate ;) I used the coefficient generator from minidsp but modified the spreadsheet so that it generated the coefficients for the Audioweaver biquad correctly. (the a1 and a2 coefficients need to be negated). See below for an example ;)

cheers

david

 

 

Linkwitz Transform

 

yoke
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Thanks David, will give it a try