Testing actual cone excursion

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Does anyone have any idea for testing actual cone excursion? I am waiting on the parts to come in for my wallen jig to work with speaker workshop and when it is up and running I want to play around with Dual Chamber Reflex enclosure to see how much effect different DCR setups have on freq responses for subwoofers nnd also excusion numbers for the more excursion limited drivers.

I have thought through a couple of options and none have seemed to pan out in a realistic $ factor. Everything so far has left me with a null. Either the equipment is too expensive for a diy experiment or might add mass to the cone of the driver which would totally hose the T/S specs of the driver (IE attaching something to the cone of the driver to test excursion).

Thoughts or suggestions?
 
You know... I actually did this once before :smash:

I must admit, it does put your drivers at risk of damage... But I was doing an uber-cheap design and the drivers had a stiff dust cap, so it was okay for me:

I used a pin with the flat end towards the driver, held in a slightly softened clamp (I used cloth and sponge to prevent damage), and moved it towards the centre of the dust cap at the excursion to be tested. Once I could see (or in my case, hear) the pin touching the driver, I stopped moving the pin closer. Then I stopped the driver, and got out my steel micrometer :D

Measure the distance between the pin when it's just touching the driver to it's rest position.

If you're worried about the pin damaging your expensive speakers, put a tiny, tiny dab of superglue in the centre of the driver. I know you're obviously not going to want to do this with £50+ drivers, but if you're spending that kind of money why the hell are you trying to do it the cheap way? :p

Hope this helped ;)

Karry
 
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