Xmax measurement

[dumrum]

I had come across a means to measure the Xmax of a driver some where on the net, or in DIY, but I just cant recall where..and no means to locate it.
I saw a means by which Xmax of a Woofer can be ,easured with a 1.5 volt cell. Could anyone please tell me how it can be done?

Thanks,
Linoj.

[SY]

A battery will not exercise a driver to Xmax. And you risk blowing the driver if you want to do a real Xmax test, which involves hitting the driver with signals big enough to take the cone/coil out of the linear region.

This is one spec that I don't measure for myself, but either take or derive from the spec sheet.

[rabbitz]

If you haven't got the xmax but have the voice coil length and air gap height from the spec sheet you can calculate it.

Xmax=(voice coil length - air gap height) / 2

Some drivers you can see under the spider and can get a measurement there but most have the voice coil out of view.