Originally Posted by velocci
Hi all, does anyone have a rough idea of how many watts on average goes into a surround or rear speaker? I know it depends on the AVR used or the volume, but I'm interested in knowing a rough percentage relative to the front speakers. so if there is an average of 50 watts going into the front speakers while watching a movie, how many do you think are going into the surround or rear? half? a quarter? 10%? Has anyone on the internet tested this?
Well it depends. First of all the AVR doesn't really matter, at least not in context of your question, it is merely a source of power. There are a couple of factors, first and foremost is what is the sensitivity rating of the surrounds and the front. The second question is what kind of SPL are you looking for? How far away are you sitting? And lastly how loud was the source mixed in regards to the surround channels, they vary from movie to movie.
Lets assume a sensitivity of 90db 1w/m, which is fairly average. You may or may not know but that determines how loud the speaker will be at a given wattage. Every time you double the watts you add about 3db of volume. So 1 watt will get you 90db, 2 watts 93db, 4 96db, 8 99db, 16 102db, 32 105db, 64 108db, at 1 meter from the speaker. Assume you sit 2 meters away, double the distance from the source and the SPL drops by about 6db so at your sitting position it would be about 102db from the front speakers. 102db is about as loud as a gas lawnmower for reference. I have NO source for this, but I would assume the surround channels are mixed to about the same "reference" volume maybe a little less, so you could assume about that same amount of power is going to them.
All that said the "Reference Level" you hear people talking about is 85 db at the listening position with 105 db peaks. So to get "reference level" SPL at your listening position only takes about 2 watts of power. Most movie theaters are set at reference level, so consider how loud it was the last time you saw a movie in the theater and thats the volume level. Most people don't listen that loud at home, some do, but most don't.
TL;DR No I don't know that anyone has measured it. Mainly because there isn't a set way to measure it, you could send a test tone to all the speakers and measure the SPL and work backwards, but thats not accurate in the real world with something like a movie or even music.