Speaker Design: Background and Parameters
Thiele/Small Parameters
Acoustics pioneers Neville Thiele and Richard Small developed a way to predict speaker
performance and frequency response. These parameters are known collectively as
“Thiele/Small Parameters”, and are divided into physical characteristics and response
parameters:
The Physical Characteristics of a speaker are:
Re:
The D.C. resistance of the voice coil measured in Ohms.
Sd:
The surface area of the speaker’s cone.
BL:
The magnetic strength of the motor structure.
Mms:
The total moving mass of the speaker including the small amount of air in front
of and behind the cone.
Cms:
The stiffness of the driver’s suspension.
Rms:
The losses due to the suspension.
The Thiele/Small Response parameters are:
Re:
The D.C. resistance of the voice coil measured in Ohms.
Sd:
The surface area of the speaker.
Fs:
The resonant frequency of the speaker.
Qes:
The electrical “Q” of the speaker.
Qms: The
mechanical
“Q” of the speaker.
Qts:
The total "Q" of the speaker.
Vas:
The volume of air having the same acoustic compliance as the speaker’s
suspension.
The mechanical and electrical parameters of the Legatia L3 driver are amenable to a variety of
different installations and speaker locations. The high Qms and Qts of the driver will allow it
to be used in an infinite baffle configuration. Hybrid Audio has also had great success using
this driver in a dipole configuration, a.k.a “open baffle”, and in larger vented enclosures. The
size of the unit allows it to be mounted in locations previously unheard of with other speakers.
This driver can be mounted on a-pillars, in dashboards or kick panels, or anywhere your
imagination takes you. The design goes hand in hand with fool-proof, high-end sound quality
with minimal work.
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