HappyPantherFan
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- Jun 22, 2023
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Hello ASR, thank you in advance for answering my silly question. I have a hunch that this has been standardized in the industry, only that I'm not good enough at googling.
As we know, there are two ways wave-forms add: for coherent ones, two equal signals in phase adds into something with 2x amplitude and 4x power; for non-coherent ones (say, two signals with different frequencies, same amplitude), the amplitude doubles as well as the power. Basis for free power of proper bi-amping. But viewed another way, the power is cut in half if an amplitude 'budget' is split equally between two signals.
It's easy to deduct further that for the 32-tone test signal we sometimes see in reviews, the output power is 1/32 of the a 1kHz sine of the same peak voltage... For an amp that is rated for 50W, it can only hope to output 50/32 = 1.5625 W of said 32-tone signal, and be already at the brink of clipping!!! That is, my hypothetical 50W amplifier has trouble pumping out even 2 Watts of real music power into speakers... Can barely reach 85 dB SPL @ 1m using an ordinary 83dB-per-watt speaker, oh boy.
Or is it that, any designer worth his salt would construct amplifiers, such that a 50W-1Vrms sensitivity design can output voltages corresponding to 50*32=1600W pure sine[1], and really won't clip a 5.657 Vrms input[2]? This way, the sustained output may be 50W only, but it outputs 50W real music power (modeled with a 32-tone) as well as pure sines.
[1]: sqrt(1600W * 4 ohm) = 80 Vrms, or 113V peak, 226 Vpp
[2]: =1Vrms * sqrt(32), the level needed for a 32-tone to have the same power as a 1Vrms pure sine
I really hope it's the latter. If so, that'd explain the always-too-low sensitivity figures of power amps - sure, 0dbV sine gets us max power already, but it'd take 32-tone of some +16 dBV amplitude to output that much power into our speakers, so they actually do not clip before that. Totally ready to be plugged to a DAC whose 0 dBFS = 2 Vrms. Or am I wrong, and everyone really needs that 1600W amp to drive his/her 83 dB/W @ 1m speaker to 'fill the house'?
As we know, there are two ways wave-forms add: for coherent ones, two equal signals in phase adds into something with 2x amplitude and 4x power; for non-coherent ones (say, two signals with different frequencies, same amplitude), the amplitude doubles as well as the power. Basis for free power of proper bi-amping. But viewed another way, the power is cut in half if an amplitude 'budget' is split equally between two signals.
It's easy to deduct further that for the 32-tone test signal we sometimes see in reviews, the output power is 1/32 of the a 1kHz sine of the same peak voltage... For an amp that is rated for 50W, it can only hope to output 50/32 = 1.5625 W of said 32-tone signal, and be already at the brink of clipping!!! That is, my hypothetical 50W amplifier has trouble pumping out even 2 Watts of real music power into speakers... Can barely reach 85 dB SPL @ 1m using an ordinary 83dB-per-watt speaker, oh boy.
Or is it that, any designer worth his salt would construct amplifiers, such that a 50W-1Vrms sensitivity design can output voltages corresponding to 50*32=1600W pure sine[1], and really won't clip a 5.657 Vrms input[2]? This way, the sustained output may be 50W only, but it outputs 50W real music power (modeled with a 32-tone) as well as pure sines.
[1]: sqrt(1600W * 4 ohm) = 80 Vrms, or 113V peak, 226 Vpp
[2]: =1Vrms * sqrt(32), the level needed for a 32-tone to have the same power as a 1Vrms pure sine
I really hope it's the latter. If so, that'd explain the always-too-low sensitivity figures of power amps - sure, 0dbV sine gets us max power already, but it'd take 32-tone of some +16 dBV amplitude to output that much power into our speakers, so they actually do not clip before that. Totally ready to be plugged to a DAC whose 0 dBFS = 2 Vrms. Or am I wrong, and everyone really needs that 1600W amp to drive his/her 83 dB/W @ 1m speaker to 'fill the house'?