Originally Posted by xray777
is there a simple formula like taking the power for 1ch driven into 8ohm and dividing by the number of channels used to get the per channel output of an AVR? 80% of my application will be for HT. I'd love to put anything above a clean 100wpc x9 but dont have the budget for an amp at this point.
What you're describing is dynamic power numbers, and for the most part useless unless you use one speaker...
Power quotes from manufacturers (USA) still have guidelines set down in the early 70's that they follow, and haven't changed. The problem is most receivers these days are multi channel, so the manufacturers use those two channels driven numbers, then spread them around to the other 3-5-7 channels in a manner to make you think you'll get 100wpc all channels driven, but few deliver.
The FTC needs to update their guidelines. What you won't see very often is a given number for "all channels driven". Harman Kardon used to use that phrase, like back in the early 2000's, but found consumers would gravitate towards better looking numbers from Denon Marantz, etc. My first 5 channel AVR was a HK AVR-525 and had 80wpc "All Channels Driven". And it delivered 80wpc in 5 channel mode. They couldn't say it if the AVR couldn't deliver 80wpc all channels driven. In two channel mode I think it delivered about 150wpc. And sounded good doing it. That thing is still alive, my sister has it. Tough piece that one! And a great space heater this time of the year.
There have been a lot of threads on AVS trying to decode manufacturers specs. If you see a spec claim 125wpc, and implies you'll get 125wpc out to all 7 channels, take a look at the total power consumption first. If that AVR uses 600w total, well 600/7 is not 125w, and when you figure the HDMI/video section uses 150w (guessing here) then that crimps the wattage going to the audio even more. You have to read all the specs to get a picture of what a particular AVR is capable of delivering into all channel. Deception is the name of the game!