Theile-Small Parameters
B: Magnetic flux density in gap, in Tesla-meters ™
BL: The magnetic strength of the motor structure.
C: Propagation velocity of sound at STP, approx. 342 m/s
Cas: Acoustical equivalent of Cms
Cmes: The electrical capacitive equivalent of Mms, in farads
Cms: The driver's mechanical compliance (reciprocal of stiffness), in m/N
D: Effective diameter of driver, in meters
F3: -3 dB cutoff frequency, in Hz
Fb: Enclosure resonance (usually for bass reflex systems), in Hz
Fc: System resonance (usually for sealed box systems), in Hz
Fs: Driver free air resonance, in Hz. This is the point at which driver impedance is maximum.
L: length of wire immersed in magnetic field, in meters
Lces: The electrical inductive equivalent of Cms, in henries
L: Length of wire immersed in magnetic field, in meters
Ms: The total moving mass of the loudspeaker cone.
Mmd: Diaphram mass, in grams
Mms: The driver's effective mechanical mass (including air load), in kg
n0: The reference efficiency of the system (eta sub 0) dimensionless, usually expressed as %
p: (rho) Density of air at STP 1.18 kg/m^3
Pa: Acoustical power
Pe: Electrical power
Q: The relative damping of a loudspeaker
Qa: The system's Q at Fb, due to absorption losses; dimensionless
Qec: The system's Q at resonance (Fc), due to electrical losses; dimensionless
Qes: The driver's Q at resonance (Fs), due to electrical losses; dimensionless
Ql: The system's Q at Fb, due to leakage losses; dimensionless
Qmc: The system's Q at resonance (Fc), due to mechanical losses; dimensionless
Qms: The driver's Q at resonance (Fs), due to mechanical losses; dimensionless
Qp: The system's Q at Fb, due to port losses (turbulence, viscousity, etc.); dimensionless
Qtc: The system's Q at resonance (Fc), due to all losses; dimensionless
Qts: The driver's Q at resonance (Fs), due to all losses; dimensionless
R: Ripple, in dB
Ras: Acoustical equivalent of Rms
Res: The electrical resistive equivalent of Rms, in ohms
Revc: DC voice coil resistance, in ohms
Rg: Amplifier source resistance (includes leads, crossover, etc.), in ohms
Rms: The driver's mechanical losses, in kg/s
Sd: Effective piston radiating area of driver, in square meters
SPLo: Sound Pressure Level, usually measured at 1 watt, at 1 meter in front of the loudspeaker
Vas: "Equivalent volume of compliance", this is a volume of air whose compliance is the same as a driver's acoustical compliance Cms (q.v.), in cubic meters
Vd: Maximum linear volume of displacement of the driver (product of Sd times Xmax), in cubic meters.
Xmax: Maximum peak linear excursion of driver, in meters
[ December 11, 2003, 10:34: Message edited by: BlackIce ]