FabFilter User Forum
Linear Phase Modes
The user manual describes how linear phase (low) has less resolution, especially in low frequencies. Could you please explain this to me, the more technical the better.
I was pondering if this meant accuracy of frequency selection or related to rippling in stop/pass bands.
Many Thanks
Paul — Jan 13, 2019
Hi Paul,
In Linear Phase mode, the frequency spectrum is essentially divided into "bins" of equal width in Hz. For example, with Medium resolution at a 44.1 kHz sample rate, we use 4096 spectrum points, so each "bin" is about 11 Hz wide (44100/4096). As you can see, if you want a sharp peak or dip around 50 Hz, a resolution of 11 Hz doesn't give you enough points to properly specify this. The frequency curve will approximate what you want, but it doesn't really map to the ideal curve that you're seeing in the display. It will be less steep and have ripples.
Another way to put it: at each point (so 0, 11, 22, 33, 44 Hz etc) the curve will be exactly what it should be, but it will ripple in between if the gain change between the points is quite large. You need more points to get a better approximation.
Cheers,
Thank you for that, this is great!
I have another question, if okay. What is the bin width in Hz for Low resolution mode? As I use this mode on parallel channels.
Many Thanks,
Paul
Hi Paul,
In Low resolution mode we use half the resolution, so then you end up with a 21.5 Hz bin size at 44.1 kHz.
Cheers,