Axiom Home Page Forums General Discussion Home Theater Just got my Epic 80 7.1 and I'm underwhelmed

Also keep in mind that, since power = I^2(R), you are asking the amp to deliver about 40% more current at 4 ohms than at 8 ohms. Although it may be capable of doing this without tripping, you could start to encounter clipping or distortion past 70W with a 4 ohm speaker.

I've always wondered if the amplifier really knows what resistance the speakers are... From my limited education in circuits, I've just aways assumed that power (watts) is power...be it at a 4 ohm resistance or 8 ohm eventually your amp is going to run out it. But the end result would still have the same volume (dB). wrong?

I used regular screws without anchors, and i'm sure not in wall studs, and everything is rock solid.

When amps are rated, they are rated assuming a certain load (usually 8 ohms). As such, the amp can deliver x amount of amps when that resistance load is connected. Lowering the resistance means the amp must deliver more current to equal the same power output.

And more distortion.

Does this mean I have to retract my smart-ass answer and posted diagram?

that would not be necessary

I have the outdoor speakers and they work really well. Now the kids can play Rockband inside we can listen to Ipod music on the deck. Or more importantly, listen to the Yankees baseball game from outside!

Steve, as we've pointed out(along with others)on numerous previous occasions, that sort of advice in the manuals about a lower impedance switch or menu setting may be fine for keeping the UL happy by possibly limiting overheating, but it's terrible advice from the standpoint of maximum performance and should be disregarded. All it does is to reduce the maximum voltage that the power supply section of the receiver can output, and following Ohm's Law again, when the voltage is limited so is the current(I=E/R)and the resulting maximum power output capability(P=IxE). Tests such as those by S&V indicate that typically the output is roughly cut in half.

Also, in considering how much current a speaker uses at a given sound level, speaker sensitivity has to be taken into account, and a speaker such as the M80 with slightly above average sensitivity can actually require the same or even less current for a given sound level than an 8 ohm speaker of less sensitivity. For example, if the M80 required 50 watts for a brief peak, the current required would be (square root)50/4=3.53 amperes; for the same brief peak a speaker of 3dB less sensitivity requiring twice the power(e.g., the M3)at 8 ohms would similarly require (square root)100/8=3.53 amperes.

Must say I agree about not liking the brackets, but for a different reason: getting the speakers properly sitting on the bracket is a nightmare. I actually dropped one of them cause I thought it was mounted when it wasn't (fortunately, caught it on the way down, but not before the wall was scored).

Something to guide the speakers into the brackets would sure be useful.

Regards,
David