Power consumption question

[StanleyMuso]

I've been looking at the specs of some amps and AV receivers. What exactly does the power consumption figure (in watts) represent? For example, one well known brand quotes power consumption as 450 watts. Is this the amount this baby will goble up on a continuous basis, or only when it is driven to its peak?

Thanks in advance for satisfying my curiosity.

[risabet]

I've been looking at the specs of some amps and AV receivers. What exactly does the power consumption figure (in watts) represent? For example, one well known brand quotes power consumption as 450 watts. Is this the amount this baby will goble up on a continuous basis, or only when it is driven to its peak?

Thanks in advance for satisfying my curiosity.

It depends, some pure class-A amps will consume high power at idle. For a class A/B amp that would probably be when driven to full output.

[StanleyMuso]

most AV receivers would not be class A? I was looking at the Marantz 5500 and its says its power consumption is 450W. I suppose at idle or quiet listening, the consumption would be a lot less?

Coincidentally, my Musical Fidelity A3.2cr is also rated at 450 watts, but this is only a two channel amp. I was thinking of getting an AV receiver and routing the two front channels throught the Musical Fidelity. When I saw the consumption figures --whoa-- the two together would be pulling almost as much power as a small heater. Am I correct in my assumption?

[risabet]

most AV receivers would not be class A? I was looking at the Marantz 5500 and its says its power consumption is 450W. I suppose at idle or quiet listening, the consumption would be a lot less?

Coincidentally, my Musical Fidelity A3.2cr is also rated at 450 watts, but this is only a two channel amp. I was thinking of getting an AV receiver and routing the two front channels throught the Musical Fidelity. When I saw the consumption figures --whoa-- the two together would be pulling almost as much power as a small heater. Am I correct in my assumption?

Yeah, at idle and low power levels the consumption is low. The two units together will only draw the maximum power at full output. It is pretty unlikely that you will have both units at full output at the same time and even if you did, a standard household curcuit can support an 1800 watt load 120V x 15 Amps= 1800VA. Don't worry about power consumption.

[StanleyMuso]

You have put my mind at ease.

[cam]

I have a question regarding power consumption in relation to the audio watts produced. My Denon 1804 has a consumption of 4.5 amps which works out to 540 watts max power consumption. Audio watts is rated at 90 x 6 even though it can't produce this with all channels driven. It wieghs in at 11.9 kg. Now the Yamaha 1500 and 2500 are rated at 110 x 7 and 120 x 7 respectively but both have a max power consumption of 500 watts max which is 40 watts less then my Denon. Both Yamahas wiegh in at 15.5 kg which is quiet a bit more. What is the reason why both those Yammies can produce more audio power with less max power consumption.

[hermanv]

The published AC line power consumption numbers are related to agency approvals of fuses power cords etc. They have little relationship to output power in watts.

As you should know even when stated in RMS there are a lot of ways to skew the numbers of output amplifier power ratings not the least of which is outright lying. By measuring over a short time window, by having a heatsink that really won't support continuous output at that level, by measuring only one channel of a multi channel design by using different peak to avaerage weigthing by measuring at a single frequency the list just goes on and on. Consider Watts as a guide not as an absolute input to a decision point.

Remember it takes roughly a 3dB change before the ouput level has changed enough to be noticed. 3 dB means that to improve on 50Watts you need 100, to improve on 100 Watts you need 200.

Usually more is better but don't get too seduced by power ratings, speaker efficiencies are all over the place with 3 dB differences very common. There is little relation between watts and sound quality except maybe for the deepest bass.