Reference / Math Measurement

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• Acoustic Power Efficiency — Loudspeaker efficiency (η):
• Active Crossover — High-Pass Biquad (IIR) — Digital Butterworth HPF coefficients:
• Amplifier Efficiency Classes — Class A:
• Bandpass Enclosure — 4th-order bandpass — two chamber volumes:
• Battery Runtime Calculation — How long will battery power the system without alternator?
• Box Volume from Dimensions — Rectangular:
• CEA-2006 Amplifier Rating Standard — Conditions for valid CEA-2006 rating:
• Damping Factor — Definition:
• Distortion Measurement Procedure — THD+N measurement:
• First-Order (6 dB/octave) Crossover — Component values:
• Fourth-Order Linkwitz-Riley (24 dB/octave) — Most common professional crossover order.
• Ground Resistance and Noise — Ground loop noise voltage:
• Impedance Measurement Procedure — Two-resistor method:
• Measuring Amplifier Gain — Procedure for setting and verifying gain:
• Measuring Frequency Response — Equipment:
• Measuring SPL (Maximum Output) — Standard test conditions:
• Ohm's Law and Power — The foundation of all electrical work in car audio.
• Parametric EQ Biquad Coefficients — Peaking filter:
• Ported Box — Helmholtz Resonance — Tuning frequency:
• Power Measurement — True power (real power):
• RMS Power from Waveforms — Sine wave:
• Room Modes and Cabin Resonance — Axial room modes (one dimension):
• SPL Addition — Adding independent sources (different signals):
• SPL vs Power vs Distance — SPL from power:
• Sealed Box — System Parameters — System resonance:
• Second-Order (12 dB/octave) Butterworth — Component values:
• Speaker Impedance — Series and Parallel — Series:
• Speed of Sound — c = 331.4 × √(1 + T_celsius / 273.15) [m/s]
• Voltage Drop in DC Circuits — Formula:
• Wavelength — λ = c / f