Keith_W DSP system

[OCA]

Funny -- seasoned (maybe), not exactly "expert" as I don't even have a good grasp of some of its other features. I've actually been using the more "stable" standard release version recently in my old Win 10 laptop which I prefer to use for quick REW measurements over Linux. Now, I am a little piqued by the beta changes so will take a peak. To be honest, it took me quite a few months to finally get used to some of the UI changes like the new PEQ window interface so I've kept two software versions installed... it's always jarring when you can't find buttons in their "original" locations.

True that! It took me with quite a bit of a shock at first but I am slowly getting a grasp of it I guess.

 

[Keith_W]

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.

 

[Tim Link]

My take on it is that the green response is "faster" in the sense that it dies down faster. Am I looking at it right. At the same time, if the initial pulse is as loud on both of them, might the phase corrected version come across as lower in volume overall? What's the scale at the bottom? Is that seconds? If so, I think up to 0.2 is within the time fusion window, so it'll all just sound louder.

 

[Keith_W]

My take on it is that the green response is "faster" in the sense that it dies down faster. Am I looking at it right. At the same time, if the initial pulse is as loud on both of them, might the phase corrected version come across as lower in volume overall? What's the scale at the bottom? Is that seconds? If so, I think up to 0.2 is within the time fusion window, so it'll all just sound louder.

Yes, the x-axis scale is seconds. Good point about the fusion window, I didn't think of that.

 

[Music1969]

The amplitudes are much higher with the red measurement, indicating that the dynamics are better.

i dont think this true

i ask similar years ago here and this was said to be false interpretation

seems this needs to be clarified first

 

[Keith_W]

i dont think this true

i ask similar years ago here and this was said to be false interpretation

seems this needs to be clarified first

Good. I hope to have mistaken beliefs corrected. Do you know what measurement corresponds to "dynamics" then? Seems as if we all hear it, but I don't know what measurement it corresponds to. I thought it might be the height of the step response, but I am not sure.

 

[Tim Link]

Actually .2 would be 200ms. That's beyond the fusion window.

 

[3ll3d00d]

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?

No, this is nothing to do with dynamics, it's just the strength of the overall impulse at different point in time. Were these two measurements taken with the "freeze gain" option selected? if not, they're not directly comparable to each other, only relative to the initial impulse of the same measurement, which may also be misleading. I don't think "dynamics" is a quantifiable thing as it's never been defined precisely by anyone that I've ever seen (i.e. you'll get n different answers to what it might mean)

for what you are looking at (comparing measurements over time), probably you'd be better off looking at a wavelet spectrogram (e.g. in rew).

 

[Music1969]

Do you know what measurement corresponds to "dynamics" then?

maybe compression test like Erin does

i started a thread about it long ago, and it is not conclusive how to quantify dynamics but maybe compression is one part

I thought it might be the height of the step response, but I am not sure.

as mentioned before, it is not that

 

[Music1969]

I don't think "dynamics" is a quantifiable thing as it's never been defined precisely by anyone that I've ever seen (i.e. you'll get n different answers to what it might mean)

correct there is already a thread and lots of discussion over the years

Very good video in the opening post to watch - amir noted it was a good watch also

Dr. Klaus Heinz of HEDD Audio (ex ADAM Audio) - measuring speakers, in particular speaker dynamics

Darko had a great interview with the main man of Hedd Audio (founder of Adam Audio before he left Adam to start Hedd). Really interesting discussion (especially 2nd half of interview) about speaker measurements and dynamics and how to measure. Link: Klaus Heinz talks HEDD Audio Tower Mains

www.audiosciencereview.com

 

[3ll3d00d]

Assuming freeze gain wasn't selected then the relative height difference (between initial and later) could be due to a sharper/tighter initial step which is what you may get from a different phase correction. Compare the step responses to see if that is the case.