Well, I have come across something interesting. Some of you may recall from a few pages back that I was confused as to why
phase linearisation is audible, compared to no phase linearisation ...
when phase is supposed to be inaudible. I said that drivers that were phase linearised seemed to have the dynamics sucked out of them, they become more polite, but also sound lifeless.
I was wondering whether everybody is wrong about the audibility of phase, but what are the chances of some hobbyist in Australia being right and the luminaries of audio are wrong? I do not have that kind of arrogance, but I can not deny the obvious audible difference. The far more likely explanation is that said hobbyist has made a mistake or is misinterpreting information. So I convinced myself that the phase correction must have done
something to the signal, and the difference I am hearing must be something else, and not phase.
Then I hit upon the idea of looking at the impulse response. Voila!
I dug out an old measurement. The intention of the measurement was for time alignment of the midrange horn, so it contains the tweeter as well as the horn, and the sweep was taken from the MLP. I then normalized the volume of both sweeps so that the amplitude can be compared. I switched to the impulse window, and this was the result. The
red measurement shows the driver with no phase correction, and the green measurement has the phase linearisation procedure applied. The amplitudes are much higher with the red measurement, indicating that the dynamics are better.
I breathed a sigh of relief when I saw this. Finally, proof that I am not imagining it.
But this raises even more questions.
1. Do you think this is a valid way to measure the subjective phenomenon of dynamics? I have never seen anybody describe this method before. Have I invented a method, or has it been described before (and I have missed it in my reading), or is it totally wrong?
2. Why should phase linearisation kill the dynamics like that? I still have no explanation! I have been discussing this with a fellow ASR member, and he has subjectively noticed a similar phenomenon in his system - that phase linearisation kills dynamics. Of course it is possible that two ASR members using different software packages are making the same error, producing artefacts as a byproduct which kills the dynamics.
Then there are other subjective phenomena which are unrelated to dynamics which I can not explain. Like, the phase linearised version has noticeable effects on the soundstage. It seems to "lift it off the floor" and compress the vertical height (bad), and it pushes the soundstage further back and seems to make it wider (good). I am starting to wonder if a less aggressive correction will provide some desirable qualities (improved depth and width of soundstage) whilst minimizing the negative qualities (vertical compression and killing dynamics). There is no "phase target" that I am aware of, because nobody seems to think that phase is audible.