FSAF (Fast subband adaptive filtering) measurement

[John Mulcahy]

I removed the sock, and added a LR2 high pass at 20Hz. The result of this FSAF measurement confuses me, as the total distortion is reduced through the entire spectrum of the speaker, right up to 20kHz, and significantly so as well. Is there a reasonable explanation for such a change in TD throughout with only a 20Hz high pass applied?

It does seem odd, perhaps Michael will have some ideas. If I run tests over a loopback connection with artificially induced distortion the results are not affected by adding a HP on the stimulus. I wonder if room resonances are having an effect on the process and the HP is attenuating the lowest resonances? Could try higher HP frequencies and see if the results stabilise.

 

[dcibel]

Yes, the results are as expected if I compare for example a 100Hz high pass to 200Hz high pass, in that the tweeter distortion stays at the same lower level. It only becomes elevated when I include some subsonic noise in the stimulus.

I'll see if I can generate some audio track with a low frequency noise superimposed to compare with real audio.