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Q-factor formula in filtergraph~

July 9, 2013 | 6:28 am


Is it somewhere explained how the Q factor is defined for "peaknotch" filters in filtergraph~ ? It doesn’t seem to follow the typical "half-gain" or "peak -3dB" bandwidth approach. Any help would be appreciated!


July 9, 2013 | 7:14 am

Hm… I’ve never heard about the "half-gain" or "peak-3dB" approach when talking about the Q-factor. AFAIK the Q-factor of an arbitrary filter is defined as the quotient of the stored and the dissipated power. For band-pass filters, this can be approximated as the quotient of the centre frequency and the bandwidth. For peaknotch, no idea…

July 12, 2013 | 7:14 am

Hi Adam,

Thanks for trying ;)
For peak/notch filters there is indeed more than one way to define it. Some clarity from Cycling’74 on that would be appreciated to be able to transfer easily those filter into an embedded platform. Using the biquads coefficients is an option, but not so flexible and convenient.


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