Enter your Speaker Impedance, Speaker Sensitivity, Listening Distance, and Desired SPL to find your Required Amplifier Power — plus RMS and Peak Voltage, RMS Current, and Actual SPL at Distance so you know exactly how hard your amp is working and whether it has enough headroom to handle the loud parts cleanly.
Required Amplifier Power
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RMS Voltage
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Peak Voltage
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RMS Current
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Actual SPL at Distance
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Power with Headroom
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Power requirements depend on speaker sensitivity, desired SPL, listening distance, and headroom. Use P = 10^((SPL - Sensitivity + 20*log10(Distance))/10) to calculate basic power, then add headroom for dynamic peaks.
RMS voltage is the effective voltage that delivers equivalent power as DC. Peak voltage is √2 times RMS (1.414x), while peak-to-peak is twice the peak voltage (2.828x RMS).
Typical headroom ranges from 3-6 dB for most applications. Classical music may need 10-20 dB headroom for dynamic peaks, while compressed music needs less. Each 3 dB requires double the power.
Most amplifiers are voltage-limited rather than power-limited. Lower impedance loads draw more current for the same voltage, increasing power output. Halving impedance typically doubles power output.
Sound follows the inverse square law - doubling distance reduces SPL by 6 dB. This means you need 4 times more power to maintain the same SPL at twice the distance.
Use the 1W/1M rating (typically given as dB SPL at 2.83V for 8Ω speakers). Higher sensitivity speakers (>90 dB) need less power, while lower sensitivity speakers (<85 dB) need more power for the same SPL.
Yes, the calculator works for any impedance from 2Ω to 32Ω. Remember that most amplifiers produce different power levels into different impedances, and some may not be stable into very low impedances.