What Is XMAX??

[coherent_guy]

I'd like to understand what the T/S parameter Xmax is all about. It's definition is: Peak linear displacement of driver diaphragm (in millimeters). Ok, so does that mean there is non-linear displacement?

What is linear displacement in the first place?

Is this spec the maximum cone movement prior to something being exceeded in some way? What is that?

Is this spec a peak to peak figure, or one way from a drivers resting position?

I am surprised by the seemingly low Xmax figures for many woofers, less than a centimeter in most cases and a few less than a millimeter. An Xmax of 10+ millimeters is large relatively speaking, but seems small to me given 10 millimeters is less than half an inch (25.21 millimeters in one inch).

I searched the forum but did not find any explanation. Anyone out there who would like to educate me? :blink: Many thanks for all replies. . .

[edgewound]

Xmax is the maximum linear travel of the voice coil/cone before it leaves the magnetic gap. Two factors determine this: voice coil winding length and suspension travel.

Peak to peak Xmax is just that....the maximum excursion that the cone/coil can travel in either direction without leaving the gap, which would result in non-linear distortion.

[kingjames]

and here I thought Xmas was an abrreviation for Christmas.:D

[coherent_guy]

and here I thought Xmas was an abrreviation for Christmas.:D


Got me with that one kj! :o:

Thanks Edgewound, how appropriate coming from you ;)

So a D130 or D131 is built such that their VC leaves the magnetic gap beyond 0.76mm of cone movement?!?! Wow!!

(see

http://www.jblproservice.com/pdf/Thiele%20Small%20Parameters/Theile%20Parameters.pdf

for T/S parameters for JBL drivers)

[Robh3606]

JBL rates X-Max as Peak linear excursion. Their number is one way for Peak only. For Peak to Peak travel you would double that. You have to watch how it's specified as some manufacturers use the Peak to Peak as their X-Max number.

Rob:)