Vas = equivalent compliance of driver (litres) Qes = electrical Q of driver at resonance Fs = resonance frequency of driver (Hz) PEmax = maximum input power for driver Fb = resonance frequency of the system F3 = frequency at which response is down by -3dB Dia = effective driver diameter driver (cm) Xmax = peak linear displacement of driver cone (mm)then, Sd = pi*(Dia/100)^2/4 Vd = Sd*Xmax/1000 n0 = 9.64*10^(-10)*Fs^3*Vas/Qes SPL = 112 + 10*LOG(n0) K1 = (4*pi^3*Ro/c)*Fs^4*Vd^2 K2 = 112+10*LOG(K1) Par = 3*F3^4*Vd^2 Per = Par/n0 PeakSPL = SPL+10*LOG(PEmax) where, pi = 3.14159265359 c = speed of sound in air (345 m/s) Ro = density of air (1.18 kg/m^3) n0 = free-air efficiency of driver SPL = SPL of driver @1W/1M Par = maximum linear power output Per = electrical input required to produce Par PeakSPL = Thermally-limited SPL in passband Maximum output at a given frequency F can be calculated as follows: Fn2 = (F/Fs)^2 Fn4 = Fn2^2 A = (Fb/Fs)^2 B = A/Qts+Fb/(Ql*Fs) C = 1+A+(Vas/Vb)+Fb/(Fs*Qts*Ql) D = 1/Qts+Fb/(Fs*Ql) E = (97/49)*A dBmag = 10*LOG(Fn4^2/((Fn4-C*Fn2+A)^2+Fn2*(D*Fn2-B)^2)) Pmax = (K1/n0)*((Fn4-C*Fn2+A)^2+Fn2*(D*Fn2-B)^2) /(Fn4-E*Fn2+A^2) SPLmax = K2+10*LOG(Fn4^2/(Fn4-E*Fn2+A^2)) SPLtherm = PeakSPL+dBmag where, SPLmax = displacement-limited SPL at frequency F (dB/1M) SPLtherm = thermally-limited SPL at frequency F (dB/1M) |