| Decibel equation for power ratio: dB difference = 10*log(P1/P2) where P1 and P2 are the 2 power levels |
| Decibel equation for distance ratio: dB difference = 20*log(D1/D2) where D1 and D2 are the 2 distances |
| Decibel equation for voltage ratio: dB difference = 20*log(V1/V2) where V1 and V2 are the 2 voltages |
| Exponential horn equation: A2=Ta*e^(2*K*X) where A2 is the area at X distance from the throat; throat area is Ta and the flare constant K = 2*pi*Fc/C Fc is cutoff frequency and C is the speed of sound 34503 cm/sec or 13584 in/sec @ 71.9 degrees Fahrenheit |
| Hypex (Salmon) horn equation: A2=Ta*(cosh(K*X)+M*sinh(K*X))^2 for M=1 this reduces to exponential for M=0 this is hyperbolic (catenoid) |
| Mouth area: Ma=C^2/(4*pi*Fc^2) where Fc is the low cutoff For mouth area divide by size factor; 1free air, 2 wall, 4 corner, 8 room corner |
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| My 28 Hz horn's flare equation: A2=Ta*cosh(2*K*X) very close to hypex with M=0.325 |
| per Paul Klipsch (for exponential) Ta=Vb*K/2 (or) Vb=Ta*2/K |
| a horn's 2nd harmonic distortion % is 1.22*(F/Fc)*(I)^0.5 where I is acoustic watts/cm^2 at the narrowest part of the throat |
| Chinese speaker spec site: sequence is #, dia., w, ohms, dB/w, Vas, Qts, Xmax English units. search using <ctrl>F |
| Bob White's software (as in Bullock & White) |
| speed of sound calculator, also links to wavelength vs frequency |
| Ohm's Law: P=(I^2)*R P=E*I E=I*R P=(E^2)/R |
| more calculators on doctorproaudio |
| Here are links to download some horn design software I find useful: Michael Zhang's ML Util on Melhuish's site (requires MS .NET extension) excel spreadsheet LeachHornAnalysis recently published on the Asylum by Brad (hulkss) McBean's Hornresponse and some of my excel layout spreadsheets are on my subindex page 3 |