09-14-11: Kijanki
Voltage ratio in electronics is, and always has been 20log(v2/v1). Pretty much anything other than power is always 20dB(k2/k1) including sound pressure, sound level etc.
-3dB of voltage means 0.708 of a value.
i see; so in your mind a 3dB reduction in power "has always" meant that power if reduced to 0.708 of it's original value and not 0.5 of it's original value.
ok...i can see that when you drill down, there is much inconsistency among the dB equation citing crowd. you're not even consistent with almarg; at least he realizes (i think) that a 3dB reduction in power means that power has been reduced to 0.5 of it's original value.
09-14-11: Kijanki
As for power cord. What you describe is average value. Amplifier might take 10A on average but it will be taken in narrow spikes of 100A or more, causing 10V drop on your 0.1ohm power cord equivalent to 20% drop in max power.
you would blow your circuit breaker if you tried to send a 100A surge through a power cord. audio equipment is not designed for use in industrial settings, they're used in homes for the most part.
09-14-11: Kijanki
Capacitor inside is not discharging faster. The problem is that it discharges very little. If voltage drops from one peak of 120Hz full wave to the next only 50mV (ripple voltage) and amplitude is 50V then charging will be done only in arccos((50V-50mV)/50V)=2.6deg. Charging pulse will be 16.6ms*2.6deg/360deg=0.12ms. Pulses will be a little wider because of all inductance in the circuit but as Atmasphere said - in millisecond range.
i think you misunderstood my point. i was not commenting on the *length* of a pulse, i was commenting on the *frequency* of pulses. as i read atmasphere's comments, he was saying that these pulses occured at a high frequency. what i was saying is that the pulses only occur once per second - hardly what i would call high freqeuency.