Parametric (adjustable) band-type filters use a width parameter that may come as a Q (resonance) factor or as a bandwith, normally as a fraction of an octave. The tables below show equivalences from one type of representation to the other. There is no standard way to convert bandwidths to Q factors (for a start, how does one measure the -3 dB points to determine the bandwidth of a parametric bell type filter with a gain of less than 3 dB?) , but these tables may be useful nevertheless, particularly for programming DSP controllers (processors). To convert an arbitrary Q factor to bandwidth, or viceversa, you can use the BW calculator from Doctor ProAudio's calculators.
Q «» bandwidth conversion | ||||
B/W (oct.) Bandwidth |
Q |
Q | B/W (oct.) Bandwidth |
|
0,02 | 72,13 | 0,50 | 2,54 | |
0,03 | 48,09 | 0,55 | 2,35 | |
0,04 | 36,07 | 0,60 | 2,19 | |
0,05 | 28,85 | 0,65 | 2,04 | |
0,06 | 24,04 | 0,70 | 2,00 | |
0,07 | 20,61 | 0,75 | 1,80 | |
0,08 | 18,03 | 0,80 | 1,70 | |
0,09 | 16,03 | 0,85 | 1,61 | |
0,10 | 14,42 | 0,90 | 1,53 | |
0,20 | 7,21 | 0,95 | 1,46 | |
0,30 | 4,80 | 1,00 | 1,39 | |
0,40 | 3,60 | 1,10 | 1,27 | |
0,50 | 2,87 | 1,20 | 1,17 | |
0,60 | 2,39 | 1,30 | 1,08 | |
0,70 | 2,04 | 1,40 | 1,01 | |
0,80 | 1,78 | 1,50 | 0,94 | |
0,90 | 1,58 | 1,60 | 0,89 | |
1,00 | 1,41 | 1,70 | 0,84 | |
1,20 | 1,17 | 1,80 | 0,79 | |
1,40 | 0,99 | 1,90 | 0,75 | |
1,60 | 0,86 | 2,00 | 0,71 | |
1,80 | 0,75 | 3,00 | 0,48 | |
1,90 | 0,71 | 4,00 | 0,36 | |
2,00 | 0,67 | 5,00 | 0,29 | |
2,20 | 0,60 | 6,00 | 0,24 | |
2,40 | 0,54 | 8,00 | 0,18 | |
2,60 | 0,49 | 10,00 | 0,14 | |
2,80 | 0,44 | 20,00 | 0,07 | |
3,00 | 0,40 | 30,00 | 0,05 | |
B/W |
Q |
Q |
B/W |