MMD question

[kpan]

I wasn't sure where to post this question, My apologies if it's not in the right place. I have a question about. the T/S parameter MMD. Why is it that only Half of the cone and half of the spider are included in this measurement.? Thanks

 

[AllenB]

Because only part of those suspension parts move. The outer edges are fixed to the basket.

 

[benb]

NOT half the cone, half the surround!

https://speakerwizard.co.uk/driver-ts-parameters-mmd-mms/

 

[kpan]

my apologies. Thanks for they quick response

 

[Mark Tillotson]

i.e. Its an effective mass. It sounds a little wrong for the spider as most of its mass is at the outer edge which moves less, so perhaps it should be more like 0.35 or 0.4 times the total mass for many geometries.

 

[Ron E]

One way to measure it accurately is to measure driver resonance in a vacuum. THen you know exactly what the air load is.

 

[kpan]

Okay thanks. That makes some sense.