Enclosure resonances, not a big deal?

[gedlee]

Originally posted by xpert


I agree in the result, I disagree with Your - ever more well known - argumentation. This data has never been taken with loudspeakers in mind. That for they don't apply exactly.

Well as usual you are ill-informed. My wife and I did and published such a psychoacoustic study - with loudspeakers in mind. You should read more, and criticize less.

[thoriated]

<i>

If that leakage can be emphasized by room acoustics +20dB any other contribution could too. You won't seperate them, neither by measurement nor by listening.

Sure I can. A high Q resonance can often be detected and isolated. It manifests itself as 'coloration' or a smearing of detail in its milder forms, far beyond what its steady state amplitude contribution might indicate, because of its delayed and much longer lasting effect. And guess what, these are all nominally 'linear' effects. This kind of thing will not be an issue only if you listen to continuous waveforms instead of music.

I've distinctly heard sheetrock, ductwork, port resonances and panel resonances that are all fairly easy to separate from the original incident waveform from the driver. Not to mention reflections through the cone itself from within the cabinet which can also be detected and suppressed. Suppression of secondary resonant contributions is, for instance, much of the rationale for feedback control at live concerts.

[badman]

Originally posted by thoriated
<i>

Sure I can. A high Q resonance can often be detected and isolated. It manifests itself as 'coloration' or a smearing of detail in its milder forms, far beyond what its steady state amplitude contribution might indicate, because of its delayed and much longer lasting effect. And guess what, these are all nominally 'linear' effects. This kind of thing will not be an issue only if you listen to continuous waveforms instead of music.

I've distinctly heard sheetrock, ductwork, port resonances and panel resonances that are all fairly easy to separate from the original incident waveform from the driver. Not to mention reflections through the cone itself from within the cabinet which can also be detected and suppressed. Suppression of secondary resonant contributions is, for instance, much of the rationale for feedback control at live concerts.

Well put.

This argument is like tasting a bell pepper and a habanero, and then someone telling you that there's no reason to believe the habanero is hotter without measuring the capsacin (sp?) levels. These colorations, once identified, are easy for an experienced listener to hear. There are bigger problems around, but an undersized engine in a car doesn't invalidate the usefulness of an improved suspension.

[xpert]

Originally posted by gedlee


Well as usual you are ill-informed. My wife and I did and published such a psychoacoustic study - with loudspeakers in mind. You should read more, and criticize less.

'Must have been very private studies indeed. Once again You're bold in repeating Your very claims and nothing.

[xpert]

Originally posted by thoriated
<i>

Sure I can. A high Q resonance can often be detected and isolated. It manifests itself as 'coloration' or a smearing of detail in its milder forms, far beyond what its steady state amplitude contribution might indicate, because of its delayed and much longer lasting effect. And guess what, these are all nominally 'linear' effects. This kind of thing will not be an issue only if you listen to continuous waveforms instead of music.

I've distinctly heard sheetrock, ductwork, port resonances and panel resonances that are all fairly easy to separate from the original incident waveform from the driver. Not to mention reflections through the cone itself from within the cabinet which can also be detected and suppressed. Suppression of secondary resonant contributions is, for instance, much of the rationale for feedback control at live concerts.

My point is to measure it. What I am after is to describe what adverse the speaker does to the transmission of a signal. That is the very basic function of the device in consideration; signal, transmission. If there is any effect of something it can be measured today down 24bit below full level. By first principles a linear deviation of ideal/identical transmission would ever show as a deviation in group delay or amplitude response. There is no exception - period.

To investigate the sonic impact of a possible linear disturbance/distortion the one and only thing to do is to look up its trace in the amplitude/group delay vs. frequency plot. With cabinet "resonances" that are down by 20dB or more and that are LINEAR in their relation to the original signal no degradation is expected. The human hearing is by for more forgiving than todays measurement tools.

[planet10]

Originally posted by xpert
.... look up its trace in the amplitude/group delay vs. frequency plot. With cabinet "resonances" that are down by 20dB or more and that are LINEAR in their relation to the original signal no degradation is expected

The differences between merely good hifi & really great hifi are happening 30-40-50 dB down... A gross frequency response is not likely to show the absence or presence of something 40 dB down let alone give you enuff information to know what it is.

20 dB is not good enuff for me...

dave

[thoriated]

With cabinet "resonances" that are down by 20dB or more and that are LINEAR in their relation to the original signal no degradation is expected.

I doubt that any serious cites can be found that will consider acceptable as low a standard of quality as described in the above quote except possibly for incidental exposure to music where low cost is a prime consideration such as background music in commercial venues.

[xpert]

Originally posted by thoriated


I doubt that any serious cites can be found that will consider acceptable as low a standard of quality as described in the above quote except possibly for incidental exposure to music where low cost is a prime consideration such as background music in commercial venues.

U may simply calculate it: a contrubution that is 20dB down and adds linear - as cabinet walls do - will show up as:


10*log10 ( 1 + (10^20/10) ) = 10*log10 (1.01) = fetch Your calculator!

in the amplitude response. The impact on group delay will show the same orders of magnitude. If You can hear the difference, You may call for the scientists to investigate Your extraterrestial skills further.

no offnece

[planet10]

Originally posted by xpert
10*log10 ( 1 + (10^20/10) ) = 10*log10 (1.01) = fetch Your calculator!

in the amplitude response. The impact on group delay will show the same orders of magnitude. If You can hear the difference, You may call for the scientists to investigate Your extraterrestial skills further.

That was implied in my post... the low level information has negligable impact on the gross frequency response, but if you can't hear them, then woe to you if you get tossed out in the jungle and need to avoid the lions & dingos.

The ability to hear that fine detail has been evolved into us for millions of years, the ones who couldn't hear that stuff never lived to breed,

dave

[xpert]

Originally posted by planet10


That was implied in my post... the low level information has negligable impact on the gross frequency response, but if you can't hear them, then woe to you if you get tossed out in the jungle and need to avoid the lions & dingos.

The ability to hear that fine detail has been evolved into us for millions of years, the ones who couldn't hear that stuff never lived to breed,

dave

I'm really impressed how far we can discuss without understanding each other. I'm talking not of a soley signal "in the jungle" but about a deviation of amplitude response. That is that the amplitude vs frequency plot shows some +/- 0.3dB ripples - one or two of them.

U should think it over