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Continuing with my "better to look stupid and learn something than keep quiet and remain ignorant" theme, I have a couple of questions about amp current capacity.
Let's say you have an amp - like the Purifi 400 module - that's rated for max current capacity of 25A. And let's say you're driving a low-impedance, 2-ohm speaker (I know impedance varies with frequency - let's say that's the average for the sake of discussion).
My understanding is that 25 amps into 2 ohms gives 50 volts and 1250 watts, yes? But the Purifi 400 module is rated at 450w into 2 ohms, which works out to 15 amps. For 8 ohms it's even more absurd: the module is rated for 225 watts into 8 ohms, but 25 amps of current into 8 ohms is 5000 watts.
So it would appear the current capacity of the amp far exceeds its maximum wattage. This would suggest that the amp can drive almost any load without ever getting anywhere near its maximum current capacity - or, to put it differently, that if it's driven into clipping or protection it will not be because too much current is being drawn. But that doesn't make any sense (does it)? So what obvious thing am I missing?
Finally, a perhaps even dumber question: most home audio setups are going to be plugged into 20-amp circuits. How can one make full use of high-current amps rated at 25-40A if they're plugged into 20A electrical circuits?
Thanks in advance for setting me straight!
Let's say you have an amp - like the Purifi 400 module - that's rated for max current capacity of 25A. And let's say you're driving a low-impedance, 2-ohm speaker (I know impedance varies with frequency - let's say that's the average for the sake of discussion).
My understanding is that 25 amps into 2 ohms gives 50 volts and 1250 watts, yes? But the Purifi 400 module is rated at 450w into 2 ohms, which works out to 15 amps. For 8 ohms it's even more absurd: the module is rated for 225 watts into 8 ohms, but 25 amps of current into 8 ohms is 5000 watts.
So it would appear the current capacity of the amp far exceeds its maximum wattage. This would suggest that the amp can drive almost any load without ever getting anywhere near its maximum current capacity - or, to put it differently, that if it's driven into clipping or protection it will not be because too much current is being drawn. But that doesn't make any sense (does it)? So what obvious thing am I missing?
Finally, a perhaps even dumber question: most home audio setups are going to be plugged into 20-amp circuits. How can one make full use of high-current amps rated at 25-40A if they're plugged into 20A electrical circuits?
Thanks in advance for setting me straight!