It seems you don’t find stuffing differently effects sound and I do. There are times I have to adjust by listening, but this is not an acceptable method during production. The thing is current measures for quality control does not cover issues like these. So I am curious.
I normally do this during development. Yes, I have discovered that small differences to make a large audible difference when it covers a wide band even if as little as 1db or less, but stuffing is completely annoying because there is no way to control it. The normal weighting method does not work because skill in stuffing it can vary. These cannot be controlled at the end of production lines either. There are some methods of data collection to help identify trends if you set a system up right, but it takes hundreds to even get sufficient sampling and trending.
I had one store owner tell me that a unit that I put in his store for test listening sounded different from what I had previously let him listen to during the development process. I went to listen and agreed it was different. Although a single value capacitor from a different brand was the major cause for that particular case, stuffing also played a major role even though the weight measured within 1 gram of tolerance.
I don't know how much stuffing affects the sound, I've never tested it, so maybe I do find it as different as you. But I am surely not going to do tests where I know what is what from trial to trail since that would be meaningless data.
If your quality control cannot make speakers that sound virtually identical one after the other then you don't have very good quality control. If you can hear a difference then you have to be able to measure a difference. If you can't find it then there is something that you don't understand. In my experience if that occurs it is usually psychological in nature.
I did a paper back in the 80's on box stuffing materials and measurements. It was an AES publication. We showed that the impedance curve would show very small changes in the box stuffing material amount etc. even when these were hard to find in the acoustic measurements. But one had to use the same driver each time since the drivers impedance can be highly variant in and of itself, so you have to stabilize it to see details.
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So in production, you see a difference in impedance, say 0.2 ohm over a band. Is it due to stuffing or the driver itself. Does it mean there will be an audible difference? I guess I will have to just setup a test gig to just see how much measureable difference can occur using same driver same stuffing but just taking the stuffing out and stuffing it back in.
Maybe you could test the drivers for consistency. Then put some a random sample drivers in some random boxes and measure. THen add stuffing, then measure.
Drivers generally are within a tolerance, depending on material, you almost have to set a level which has nothing to do with whether day are audibly indistinguishable. If you look at tolerance settings on a production line, they are set to identify assembly faults rather than control of consistent sound quality.
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Yea, in the same way as speakers sound good because they sound good! Most want to find the underlying reasons for what we perceive
Not sure what you're saying here - as far as perception is concerned you are correct, there is no such thing as perfection - there are varying increasing degrees of realism in audio replay so yes, discordant sounds obviously grab our attention but there are other elements of the soundfield which can be disturb but not make it into consciousness
i made no sweeping claims about distortion i used the term to ascribe all distortion.
i just find it peculiar that in your reply you specifically referenced "non linear" distortion when you profess that it is of little importance.
He was responding to other members talking about linear and nonlinear distortion, therefore it would make sense to name the type of distortion that he wanted to talk about. Why talk about that? Because other people keep bringing it up, so it needed clarification. That's all.
Also, I don't think he was accusing you of making sweeping claims. He was trying to explain to you that some people do.
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Interesting, can you remember the pressures developed inside the enclosure relative to atmospheric?
For closed enclosures, it can simply be calculated through the general gas equation. Even with large high excursion woofers, I found it to be typically very low, .005 bar or something (it is not because of the pressure differential that enclosures need thick walls). However, I don't know how it is for bass reflex enclosures at low frequencies, and it cannot be calculated (at least by me) because it depends on the strength of the Helmholz resonance. Did you by any chance do any measurements in a BR enclosure at resonance? I would be most obliged to get some indication.
Klippel did this many many years ago while he was working at Harmon. He would build a reverse filter (a mirror filter) which would iron out the nonlinearities. This was never a product as it was much cheaper to just make the speaker better - hence his current product line. This is further proof that it is possible to make a speaker that has low enough nonlinearity that it does not matter. If this weren't possible then Klippel's mirror filter would be a viable product. With modern DSP this would be a cinch.
Example of my point: If someone says that "Dr. Geddes does not believe distortion is audible", that would be completely false. And yet I have heard that exact quote before. We must be clear about what we are talking about when we say "distortion", otherwise false statements get made and arguments persist.
So you are saying that noting current DSP technology, there is a good chance that doing this inverse speaker distortion filter with DSP cost very little. Hmmm, very interesting, I wonder who is developing such product. I think it will be major.