narrow band graphic eq

Jan 23, 2014 at 6:19am

narrow band graphic eq

Hello all,

I’ve been trying to find a way of modifying the max example of the 1/3 octave graphic eq to reduce the bandwidth of each filter, maybe suffering like 1/6 or 1/9 octave wide.

Does anybody know if this is possible or am I wasting my time?


Jan 24, 2014 at 12:24am

I’ve made a bit of headway with this – using several fffb~ objects (as the maximum number of filters per object is 50).

The only thing that I am struggling with now is the filter frequency ratio – I notice that the 1/3 octave eq quotes this as “A third-octave equalizer has a frequency ratio of the cube root of 2, i.e. 1.259921…”

I’m not sure as to where this number comes from – or the calculation to find the ratio for narrower bandwidths.

Any ideas?


Jan 24, 2014 at 7:12pm

You can get this using mtof. For third of an octave, just increment the pitch value going into mtof by 4.

Jan 24, 2014 at 8:09pm

the calculation is always the same for no matter how many keys per octave. like peter suggests, mtof, which performs the math, can also take float, and lets you do any number per octave you want.


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