FSAF (Fast subband adaptive filtering) measurement

Tikkidy said:

@dcibel

Moving somewhere that’s less prone to hurricanes, war planes doing military drills and hotted up cars from C20 roaring down the street is in the 5 year plan.

In the meantime, how can we use FSAF to see if the residual is not coming from the (rear mounted) passive radiator? The box? The room?

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I would think to use the same methods as always - neafield of woofer and PR individually and compare.

Tikkidy said:

If the answer is to build a better enclosure Eg. sealed box, another project…

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If you want to go down another rabbit hole, be my guest . Compare all the cabinets, and wonder if the cause of differences is due to change in driver excursion, air velocity, turbulence, rasonant panels, leakage, etc. Just don't forget to stop and enjoy the music once in a while...

Tikkidy said:

The ESS has some advantages in that multiple sweeps can reject plosives
I’m afraid FSAF will be misused and abused

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I would think more along the lines of "misinterpreted and misunderstood", which can be said for any/all measurements/data when the audience is the general public.

"misuse and abuse" is exactly what I am looking for. Any new technology is flaky, shaky, and full of bugs which I have not noticed because I am using FSAF too "right". It's a long way to the rock-solid perfection of a good ice-axe.

"misinterpreted and misunderstood" is out of my control, thus I try not to care... although being canceled out of the hate for my ideas is hardly a pleasant experience. Same GULAG, over and over again. There always will be people who object to your ideas by physically exterminating you.

FSAF​

You're all about sad things. How to use FSAF features? I played the music track. FSAF recorded this track. Then he compared the mathematical decomposition of the source and the recorded one. There was a difference. You can listen to it. Try to remember which frequencies have the highest levels. Decide how this happened, that is, who is to blame. And this is all against the backdrop of doubts, or maybe the difference is insignificant, maybe everything is almost fine. Then why keep looking? Maybe visualization of the remainder is needed? Spectral or in the form of a graph of % remainder over all frequencies? Then it will be easier and faster to evaluate the measurement result. It also seems to me that to use FSAF you do not need any music signal, such as mp3, but, on the contrary, the highest quality signal, more than 44100 16 bits. Maybe such a test track should be created. 32 bit floating point, 96 kHz. Or find it if it already exists somewhere. Then the difference will show approximately what a person can determine for himself, without programs, whether the musical instruments performed by the speaker under test sound true.

The best test tracks "objectively" are the same as the hardest to compress - live unedited chamber acoustic with voice, like a jazz piano trio accompanying a singer. Too many instruments - easier. Too much editing - easier. Without voice - easier. Without piano - easier. Also, it must be a very good performance of very good music (for you) - otherwise, you'll start hating it after listening to the same piece so many times.

I am all for visualizations, like

... which can pinpoint internal resonances and motor hysteresis distortions. Here, the source was bandlimited to 200...1000Hz and it's obvious that the residual is spread all over the map, far and wide. I am not sure how to condense them into a single value. Also, such visualizations require a low-noise mic like Rode NT1 5th gen and a low RT60 room. Otherwise, your ears are vastly superior to any visualizations.

A regular, high level of distortion is easily audible as residual, and visible on spectrograms. The lower, more marginal distortions sound like a cheap piano (while the real one was a true concert grand piano) and an amateur nervous signer with poor voice control (while the real one was flawlessly smooth). These are still possible to detect on residuals. When you change your listening habits, even stop listening to music - that's a sign of an even lower level of distortion. I am not sure if FSAF can help with those (yet:-).

I mentioned previously, a useful free tool for spectrogram visualization is Sonic Visualiser: