Hey
I am using this project in Rpi - bmc0/dsp
It allows to set various effects and DSP setting to the entire audio stream of the device.
I wanted to get some common preset values like Pop, Dance, Rock, Classic, etc
The eq has the format of
I did get certain values from here and here and here
But all of them did not have a reference for the Q values because of which the EQ did not turn out as imagined.
Is there some material or online generator to get values of presets? Since what I found only had Freq and db levels, I did not know what to set the values of Q. I have been searching like anythin for past two nights. I thought it would be much better to get some guidance rather than getting distressed.
Thank you.
I am using this project in Rpi - bmc0/dsp
It allows to set various effects and DSP setting to the entire audio stream of the device.
I wanted to get some common preset values like Pop, Dance, Rock, Classic, etc
The eq has the format of
Code:
eq f0[k] width[q|o|h|k] gainBut all of them did not have a reference for the Q values because of which the EQ did not turn out as imagined.
Is there some material or online generator to get values of presets? Since what I found only had Freq and db levels, I did not know what to set the values of Q. I have been searching like anythin for past two nights. I thought it would be much better to get some guidance rather than getting distressed.
Thank you.
1st problem is that Q has no exact definition --> what they decided is the Q:bandwidth relation.
For 1st order IIR filter Q=0.5 and for 2nd order IIR filter sqrt(0.5) could be used as a default bandwidth but, it can be variable as well (anything between lets say 0.05 and 100). Sometimes Q is even put work as bw/oct.
To solve their Q -base and values used in those presets, I would try to take the responses out from those filters and then make some comparisons using MatLab or Octave as for an example. Here's some ready to use code for common biquad filters -
https://users.aalto.fi/~ssarkka/pub/eq-design-demo.zip
There are also online calculators you could use to check the Q:bandwidth relations - Q factor vs bandwidth in octaves band filter -3 dB pass calculator calculation formula quality factor Q to bandwidth BW width octave convert filter BW octave vibration mastering slope dB/oct steepness EQ filter equalizer cutoff freqiency - sengpielau
For 1st order IIR filter Q=0.5 and for 2nd order IIR filter sqrt(0.5) could be used as a default bandwidth but, it can be variable as well (anything between lets say 0.05 and 100). Sometimes Q is even put work as bw/oct.
To solve their Q -base and values used in those presets, I would try to take the responses out from those filters and then make some comparisons using MatLab or Octave as for an example. Here's some ready to use code for common biquad filters -
https://users.aalto.fi/~ssarkka/pub/eq-design-demo.zip
There are also online calculators you could use to check the Q:bandwidth relations - Q factor vs bandwidth in octaves band filter -3 dB pass calculator calculation formula quality factor Q to bandwidth BW width octave convert filter BW octave vibration mastering slope dB/oct steepness EQ filter equalizer cutoff freqiency - sengpielau
I did take 1.0 as the default but that did not yield the desired result.
For your reference this is what I had set, just for the Rock preset
eq <f0[k]> <width[q|o|h|k]> <gain>
eq 20000 1.0 7.3
eq 10000 1.0 7.3
eq 5000 1.0 6.7
eq 3500 1.0 3.0
eq 2500 1.0 -3.0
eq 1750 1.0 -5.7
eq 1250 1.0 -6.6
..
..
For your reference this is what I had set, just for the Rock preset
eq <f0[k]> <width[q|o|h|k]> <gain>
eq 20000 1.0 7.3
eq 10000 1.0 7.3
eq 5000 1.0 6.7
eq 3500 1.0 3.0
eq 2500 1.0 -3.0
eq 1750 1.0 -5.7
eq 1250 1.0 -6.6
..
..
Not a surprise. Default value usually is sqrt(0.5) ... = 0.7071... but EQ filter might have it differently set (depends on count of the EQ bands).
Did you dig those three other projects as I suggested ... ?
Is there a possibility to plot the output from the filters one by one you have selected for your preset with Q set to 0.7071...?
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