Anyone know of a formula for calculating Xmax from all the other speaker peramaters??? Like Vas, Diam.
Ralph
Ralph
To my knowledge, you can't get it from Vas, diameter,or any Thiele-Small parameters.
You can get it from length of voice coil and length of magnetic gap, (air gap). These measurements are frequently listed.
The formula: Excursion(+ or -) = (voice coil length - magnetic gap length) / 2.
Example: A speaker with a voice coild length of 17 mm has a 6 mm air gap, (magnetic gap). What is the excursion?
Answer: (17mm - 6mm) / 2 = 11mm / 2 = 5.5 mm.
the excursion is 5.5 mm.
The DuMax method is sometimes used to measure the excursion, and it sometimes comes out just a little bit longer than this method. But the difference is not significant.
This method will give you the answer you need.
You can get it from length of voice coil and length of magnetic gap, (air gap). These measurements are frequently listed.
The formula: Excursion(+ or -) = (voice coil length - magnetic gap length) / 2.
Example: A speaker with a voice coild length of 17 mm has a 6 mm air gap, (magnetic gap). What is the excursion?
Answer: (17mm - 6mm) / 2 = 11mm / 2 = 5.5 mm.
the excursion is 5.5 mm.
The DuMax method is sometimes used to measure the excursion, and it sometimes comes out just a little bit longer than this method. But the difference is not significant.
This method will give you the answer you need.
By the way, this is for linear excursion. The max excursion, for hi fi speakers, is usually 50% to 100% longer.
The max excursion for PA speakers is frequently even longer than that.
The max excursion for PA speakers is frequently even longer than that.
PPS: Sometimes a manufacturer will publish the voice coil length, but not the air gap, (magnetic gap), length.
In that case, it probably is a fair guess that for most midbasses and woofers, unless these are special speakers, will have a magnetic gap between 6 and 8 mm. You are probably reasonably safe with that.
In that case, it probably is a fair guess that for most midbasses and woofers, unless these are special speakers, will have a magnetic gap between 6 and 8 mm. You are probably reasonably safe with that.
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