Hybrid Audio Technologies Legatia Pro - Manual (Page 7)

Legatia Pro User’s Manual ©Hybrid Audio Technologies Page 7 of 43
Thiele/Small Parameters Introduction
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.
Application to Thiele/Small Parameters to Legatia Pro Designs
Enclosure Recommendations
All Legatia Pro-series drivers include a sealed-back tuned chamber, and therefore do not require
being mounted in an enclosure. In a typical installation, Legatia Pro midrange and tweeter products
should be mounted in a solid mounting baffle to abate resonance (details on baffle recommendations
are presented on page 37).