Hello I am currently selecting AV equipment for a home theater I am designing. I am wondering about pre-outs on my AV receiver. I have Marantz SR7015 and a 7.2.4 theater setup. I am using an Emotiva BasX A3 powered amplifier for my LCR speakers. My question is this:
The receiver is rated for 125w with 2 channels driven. When you use the pre-outs for the front Left,Right and Center speaker how does that affect the overall wattage output to each speaker? Or does it? I am guessing that if I was to not use an external amplifier for the front three and run a 7.2.2 atmos setup each speaker would see about 70 watts. If three of those speakers are powered from an external amplifier will the theoretical wattage of 70+70+70 (LCR) be redistributed to the other speakers?
Thank you
Brad
It does not work like that at all because music signal is not constant and for 7.1.4 movies, each of the 11 channels will have different contents most of the time. It will be rare (could happen in theory, but rare in reality..) for all of the channels, or even a few of them to have the same power requirements at the same time. The only way to have all channels working almost (still not exactly) equally hard is if you use the multichannel stereo mode. In that case it will be so loud that I think you would turn the volume down a few notches unless you are having a party and want to have loud sound everywhere in the room.
Each speaker will draw the power or more accurately, current, according to the media contents and the volume setting. For example, let's say your front left channel is rated for 200 W average and 500 W peak, it may only draw 0.5 W or less on average most of the time and peaks to may be 50 W for a split second to a few seconds, if your volume is at say -30 and you are getting loud enough sound pressure level from 10 ft using speakers with average sensitivity of 87 to 90 dB.
A lot of people would likely not have spent money on amps like he BasX if they first find out how much power do their speakers actually need. However, some people will use external amps regardless, for reasons other than sound quality, or loudness.
At Audioholics, members have posted links to several online calculators numerous time for good reasons.
The most popular one appears to be the hometheaterengineering.com one:
Peak SPL Calculator (hometheaterengineering.com)
