effect of non-linearities of air on sound reproduction - diyAudio
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Old 3rd September 2013, 02:18 AM   #1
tsiros is offline tsiros  Greece
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Default effect of non-linearities of air on sound reproduction

Is there any merit in taking into consideration the fact that air is a non linear medium?
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Old 3rd September 2013, 10:20 AM   #2
DF96 is offline DF96  England
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When designing a high power horn loudspeaker, perhaps yes. Elsewhere, probably not.
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Old 4th September 2013, 08:47 PM   #3
tvrgeek is offline tvrgeek  United States
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Air's non-linearity is an issue to understand, but there is nothing to do about it in designing loudspeaker cabinets. If it means anything, it reminds you that we should not spend our time on .1% problems when there are 1% problems we can't do anything about.
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Old 5th September 2013, 02:20 AM   #4
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What non-linearity? Pressure v volume?

Other than in loudspeaker design, what problems arise? It's not like we can get rid of it...that wouldn't be hi-fi.
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Old 5th September 2013, 02:47 AM   #5
jcx is offline jcx  United States
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the linear/perfectly reversable model of air compresion/expansion in sound wave propagation is violated when thermal energy leaks by diffusion from the compression peaks

this becomes a bigger problem at higher SPL - can account for single digit % distortion in compression drivers - worse with low flare rates so there are more wavelengths in the narrow high pressure peak horn throat

also can be measurable in giant PA arrays for outdoor concerts, stadiums


seldom a 1st order probelm with domestic drivers, home listening SPL
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Old 5th September 2013, 03:58 AM   #6
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OK, thanks. Presumably related to peak pressure and frequency. I guess we want adiabatic, not isothermal?

I suppose humidity complicates the issue considerably. Is sound from speakers visible in mist? I don't think I've ever been to an outdoor concert in fog.
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Old 5th September 2013, 07:47 AM   #7
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Didn't Small write something that the volume of the loudspeaker cabinet should be more than 10 times the volume displacement of the loudspeaker, (Vd), or nonlinearities kick in?

Also, I do remember reading of an Infinity loudspeaker-several woofers in a vertical array-where the top SPL was limited by that factor.
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Old 5th September 2013, 10:16 PM   #8
tvrgeek is offline tvrgeek  United States
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About that. But proper alignment also is usually much larger, so not an issue. Maybe it helps as I prefer low Q sealed subs. I target .5.
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Old 13th September 2013, 09:45 PM   #9
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Air non-linearities create distortions of low order, and sound as if increased loudness.

Bose speakers always seem to sound louder, right?
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