[Klinkenborg]


Hi All,

 

In comparing drivers, it suddenly occurred to me that that dividing BL by Mms will give some idea about the cone's maximum acceleration based upon Force = Mass x acceleration, F = M.a  and from which a = F/M.  This is analogous to a car's power-to-weight ratio which directly affects its acceleration, and in a loudspeaker would determine its transient response to some extent.  Compare if you will the BL/Mms of the SEAS L26RFX/P at 0.201 with the Beyma 8G40 at 0.581 (units N/A and g).  I Accept that many other factors are at work here but I have not seen this specific point discussed anywhere and would be interested to hear people's views.  

 

Cheers, Carl.

 

[MBentz]

For a given frequency, the amount of acceleration required is finite. What you are referring to here is known as the mass corner and is responsible forone of the limits to HF extension.


When talking about transient response, usually we're talking about resonance or distortion. The difference in this performance is related to the Q of the system, ridgedness of the diaphragm, Doppler distortion, and excursion linearity.....not so much the HF extension of the drive unit.

 

[shadyJ]

The 'force factor' of a driver is BL^2/Re more than just BL. Re is the resistance of voice coil, and there won't be any response at all if the coil doesn't produce a magnetic field. Here is a paper that addresses your question , but be aware that not everyone agrees with the conclusions of that paper, but I do think it raises some good points.

 

[John_E_Janowitz]

Force = magnetic flux in gap ( B ) * Length of wire in gap ( l ) * current in the wire ( i )


Without current you have no force at all. Current is determined based on the resistance or impedance curve.

http://web.archive.org/web/20010810141852/lambdacoustics.com/library/whitepapers/bl_mms.htm

 

[noah katz]

this was discussed here http://www.avsforum.com/t/1497174/bl-2-re-how-is-this-the-force-factor-in-a-driver/0_50