Originally Posted by Heinrich S
Is it true that amps can't drive all speakers equally in a multichannel system because each channel has different spectral content? So the dynamic range and signal level will be different, so having equal power per channel isn't absolutely necessary?
what do you mean by "can't?"
More power is louder, right? So less power is less loud, right? this is really simple logic and if it doesn't make sense to you look at it until it does.
So if the sound is ever less than absolutely as loud as it can possibly be, you don't use all the available power at least sometimes, right? So if you turn down, you use less power.
The amount of power required at any millisecond depends entirely upon what's in the channel being reproduced. During the silent parts, zero power is used. During the silent parts zero power is used.
During the "loud" (say 80 to 85 dB) parts, for most of us,one or two watts are being used. One or two watts will make things quite loud with normal consumer speakers in normal home environments. And with real content the power will be different in each channel, from milisecond to millisecond, unless every channel contains exactly the same content. Which is not the way things are mixed.
So "can" the amp deliver equal power to each channel? Of course it can. Play a test signal in every channel at normal conversational volume (say about 65 dB) and you will be delivering the exact same amount of power to each speaker. And with typical speakers and setup you will be delivering somewhere around one or two one-hundredths of a watt, to each speaker, simultaneously. Turn it up to "loud" at 85 dB and you'll be delivering one or two watts to each speaker simultaneously.
Indeed, even if you drive the amp into severe clipping with almost every modern receiver or multichannel amp, you'll get equal power to every channel, assuming identical speakers. It'l be equally distorted, too.
The question that's confusing you is whether a receiver can deliver the same amount of clean power into 5 or 7 channels at once as it can into 2 channels at once. For the vast majority, the answer is no. Maxing out every power amp in a reeiver all at once will get you lower clean power per channel than maxing out only two at a time. With real content that's not mixed to be exactly the same and equally loud in every channel all at once, it doesn't matter, because the amps will never be required to deliver their fullest clean power to all channels all at once.