Speaker compliance

Is there a YouTube or soundcloud clip that demonstrates what it does? How does it sound when changed?


Caveat: I haven’t updated yet.
 
I'd also guess that the inward stroke also has to stretch the cone material, while the outward stroke relaxes it. I've always had the impression that speaker cones have some tension on them when at rest. If so, how is this achieved, and how does this affect the movement of the speaker?
 
DLC86 said:
(note: we guitar players probably often exceed the Xmax of our speakers since we love "break-up" so much)
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Nope, that's a common myth. Speaker's sound horrible past Xmax, not to mention you will probably reach their thermal limit before reaching maximum excursion, destroying the driver. This also happens only on lower frequencies.

DLC86 said:
Nope. In the datasheets I've seen xmax is expressed in mm and the values range between 5 and 14. I just converted it to cm cuz I had to multiply it by SD which was in cm^2.
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Nah, that definitely seems wrong for guitar speakers. Are you sure you are not looking at drivers intended for subwoofers? They are more in the range of 0.5mm to 2mm for a typical guitar speaker.
 
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DLC86 said:
I wasn't able to find all the necessary data about a particular guitar speaker to make a precise real-world example, these often have pretty poor datasheets, so I looked at a bunch of 12" PA mid-woofers and took an average of those values hoping a typical guitar speaker is not too far off from those.

...

I chose the Xmax value (maximum linear displacement) for that to have a real-world value and, in the datasheets I've seen, it ranges between 0.5 and 1.4cm, so I took 1cm as a medium value to simplify the math a bit (I'll call it X1).

(note: we guitar players probably often exceed the Xmax of our speakers since we love "break-up" so much)
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PA speakers are far off from guitar speakers in terms of Xmax . Eminence shows its guitar speakers' Thiele & Small parameters, around 0.5 - 2 mm. Mostly 0.8 or 1.27 mm, so @Rex's 1 mm seems right. Double that for Xlim if you'd like, 2 mm.

And like @AlbertA said, guitar speaker "break-up" is not a function of over excursion. It's a function of the cone acting past its pistonic band and "breaking up" into radial and concentric modes across its surface. The end effect is one that is linear and captured in IRs.
 
AlbertA said:
Nope, that's a common myth. Speaker's sound horrible past Xmax, not to mention you will probably reach their thermal limit before reaching maximum excursion, destroying the driver. This also happens only on lower frequencies.
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As I wrote earlier Xmax is not the physical limit of the speaker, that's usually called Xlim or Xmech. But I don't know more than that so you could be right.

AlbertA said:
Nah, that definitely seems wrong for guitar speakers. Are you sure you are not looking at drivers intended for subwoofers? They are more in the range of 0.5mm to 2mm for a typical guitar speaker.
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Most of the Xmax values I've seen are taken from the link I posted in my previous post in which the vast majority are mid-woofer speakers.
Anyway do you have any source for those numbers? Cuz I checked a bunch of datasheets from the major guitar speakers manufacturer (eminence, celestion, etc.) and it seems they never publish Xmax or any Small-Thiele parameters for their guitar speakers.
 
yeky83 said:
for example:
http://www.eminence.com/speakers/speaker-detail/?model=Swamp_Thang
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Doh!
I was just unlucky then, I opened a few pdf from the Legend series and didn't see it so I assumed they never published it for guitar speakers, just like celestion.

It seems you're right then, with an excursion of ~1mm the effect would be basically negligible.
But it could apply to bass or PA speakers after all, so my mental masturbation wasn't totally useless :D
 
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Just wondering if this parameter will ever make it into being visible in AxeEdit and, if so, when?
I've found it via the front panel as the final parameter in the Advanced Tab.
But it doesn't appear to be there yet in Axe Edit.
 
DLC86 said:
Doh!
I was just unlucky then, I opened just a few pdf from the Legend series and didn't see it so I assumed they never published it for guitar speakers.

It seems you're right then, with an excursion of ~1mm the effect would be basically negligible.
But it could apply to bass or PA speakers after all, so my mental masturbation hasn't been totally useless :D
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Yeah, I wonder what the effect is on bass/PA speakers. The Klippel paper I posted earlier says that speaker compliance is usually asymmetric in the extremes of excursion, maybe it's with this in mind? Dunno.
 
Just for the sake of knowledge, my physicist friend corrected me on the formula to calculate the pressure.
He said when the speaker moves forward or backwards the internal temperature increases/decreases too and that causes a slightly larger variation of the internal pressure. This whole phenomenon is defined as an "adiabatic transformation" so the adiabatic coefficient for air should be added to the formula, that's 1,41 at 20°C.
It becomes like this:

P1 = (Pr * Vr^1.4) / V1^1.4

With this addition the final percentage in the case I described goes up to 3.6%, but it would still be very low for guitar speakers with a 1mm Xmax.

yeky83 said:
Yeah, I wonder what the effect is on bass/PA speakers. The Klippel paper I posted earlier says that speaker compliance is usually asymmetric in the extremes of excursion, maybe it's with this in mind? Dunno.
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It could also be due to the geometry of the cone, of the spider or of the magnet's magnetic field. Don't know either.
 
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