I'm having a play with hornresp and it's asking this but I haven't seen this parameter in speaker data sheets before. How do I work it out from other parameters?
Press F1 when in hornresp and read through that. Especially page 9 regarding calculation of parameters.
I simply fill out Sd first then double click each field starting with Cms and ending with Bl (jump over Re as you need to enter it yourself as it cannot be calculated)
Then you double click on Sd and check the parameters it gives if they are close to the spec sheet.
Usually there will be deviation due to rounding in the spec sheet. (should still be small)
Or outright bogus data from the mfgr. I have also found mistakes where numbers where mistyped from a reputable mfgr.
I simply fill out Sd first then double click each field starting with Cms and ending with Bl (jump over Re as you need to enter it yourself as it cannot be calculated)
Then you double click on Sd and check the parameters it gives if they are close to the spec sheet.
Usually there will be deviation due to rounding in the spec sheet. (should still be small)
Or outright bogus data from the mfgr. I have also found mistakes where numbers where mistyped from a reputable mfgr.
To your original question. Rms is (are) the mechanical loss(es) of a driver. Mostly suspension related, such as viscous drag in the material. Some rubber surrounds have very high loss, foam usually low. Electrodynamic loss is here also, so aluminum voice coil formers will have lower Q. Forcing air through a cloth suspension is also an Rms contributor.
Rms is the resistance that determines Qms. (High mechanical drag gives low mechanical Q.)
David
Rms is the resistance that determines Qms. (High mechanical drag gives low mechanical Q.)
David
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