Amplifier power rating/consumption

Lawrence001

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Can someone explain why some class d amps have a higher rated output than their power consumption I've never understood that.

We may have inadvertantly solved the climate crisis!

 
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Bokke

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Can someone explain why some class d amps have a higher rated output than their power consumption I've never understood that.

We may have inadvertantly solved the climate crisis!
how will efficient class d stop countries over fishing?

 

Blzebub

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how will efficient class d stop countries over fishing?
Blow them into the weeds?

ATC amp packs are 350 wpc, idle at 80 w (warm fins) and get quite hot with use. Class A up to 2/3 max output, then AB. I use <20%, more like 10% of volume knob travel, perhaps 15% if I'm pushing it. God knows what they sound like at max output, I wouldn't dare try it.

Turned off when not in use.

 

toprepairman

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No need to over complicate this. The power shown by the manufacturer is the absolute maximum power the amp could draw if running continuously at max output. It's information mainly there for safety considerations. Virtually no user is ever going to run at max power. Most amps would have cut off after a short while in any event.

Also, consider your speaker's sensitivity (not efficiency as often erroneously quoted on this forum and elsewhere). Let's say it's 88db/w/m. That means that one speaker will produce a sound level of 88db at a distance of 1m for an input power of 1W. Now go away and google what 88db sounds like! It's loud. OK, there are dynamic peaks to consider, but you can see that your amp is only likely to need an output of a watt or two. If the amp outputs 3W, and is 33.3% efficient (i.e only 33.3% of input power is available as output power; efficiencies are always ratios [such as percentage]) then the amp requires 9W of input power to produce 3W of output power. This is very much broad brush, but it does explain tne basics.
Not quite correct, it's the max peak power the amp draws which will only happen at switch-on when the caps are being charged up.

 

Beobloke

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if you can get more power out than you put in, then the planet is saved [emoji4]
It reminds me of the micro system I saw in Asda years ago. It had stickers all over it proclaiming its maximum TWENTY watts of mighty output power.

I took a peek round the back and the supply input was from a 12V ‘wall wart’. The socket was labelled “12V, 1A max”

smile.png
 

2010*zuma

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I would say any listening session is cheaper than going to the pub or a spin in the sports car 🔥🤑

 
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simon g

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Not quite correct, it's the max peak power the amp draws which will only happen at switch-on when the caps are being charged up.
I think you are incorrect in that assertion. Please think about it and perhaps read the below, particularly the section in "AC Power Consumption" 

http://www.rocketroberts.com/techart/powerart_a.htm

"AC Power Consumption: On the back of many amplifiers you may see a label that shows (for example) "1000 watts". This is NOT the output power capability of the amplifier. This is (in almost all cases) the amount of AC power that the amplifier requires from the 120 VAC wall socket for nominal operation at full output using normal music signals. The amplifier's output power must always be less than this AC power requirement specification, because the amplifier cannot deliver more (or even as much ) power that it takes from the wall socket. All amplifiers generate heat to some degree, this is basically wasted electrical energy. Typically, if an amplifier takes 1000 watts from the wall, it might have a power rating of approximately 300 watts per channel (it really depends on the class of the amplifier's circuit class). I see vintage amplifiers on eBay all the time... and those who are offering them for sale (who admit they know little or nothing about amplifiers) often make the mistake of listing the output power of the amplifier by stating the power requirement that is listed on the back of the amp."

 
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Bokke

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how will efficient class d stop countries over fishing?
That's not the climate crisis that's overpopulation and industrialisation.
I think you'll find its more of an issue than you realise

check out the documentary on Netflix about it. its an eye opener - 80% of the sea life has been wipped out 

Plankton may absorb more of the CO2 causing climate change than previously thought, according to new research For a while, Adam Martiny and some of his fellow scientists had suspected something was not right in how researchers understand the oceans.

The CO2 is absorbed into the phytoplankton shells, and ultimately sinks to the bottom of the sea as the plankton die off. The planet’s health depends on regular plankton “blooms,” in which enormous aggregations of plankton spread for miles over the world’s oceans.

Through photosynthesis, phytoplankton consume carbon dioxide on a scale equivalent to forests and other land plants. Some of this carbon is carried to the deep ocean when phytoplankton die, and some is transferred to different layers of the ocean as phytoplankton are eaten by other creatures, which themselves reproduce, generate waste, and die.

 
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toprepairman

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I think you are incorrect in that assertion. Please think about it and perhaps read the below, particularly the section in "AC Power Consumption" 

http://www.rocketroberts.com/techart/powerart_a.htm

"AC Power Consumption: On the back of many amplifiers you may see a label that shows (for example) "1000 watts". This is NOT the output power capability of the amplifier. This is (in almost all cases) the amount of AC power that the amplifier requires from the 120 VAC wall socket for nominal operation at full output using normal music signals. The amplifier's output power must always be less than this AC power requirement specification, because the amplifier cannot deliver more (or even as much ) power that it takes from the wall socket. All amplifiers generate heat to some degree, this is basically wasted electrical energy. Typically, if an amplifier takes 1000 watts from the wall, it might have a power rating of approximately 300 watts per channel (it really depends on the class of the amplifier's circuit class). I see vintage amplifiers on eBay all the time... and those who are offering them for sale (who admit they know little or nothing about amplifiers) often make the mistake of listing the output power of the amplifier by stating the power requirement that is listed on the back of the amp."
No, sadly the rocketroberts assertion is flawed.

Taking the Brio as an example.

50W into 8Ohms.

The only way you could get it to draw a lot of power is to run it full power sine wave continuous into the rated load so 50 x 2is 100 W 78%efficient makes it just under 130W, plus lose another 10% in the power supply takes us up to 143W.

Looking at the OP's case he's listening to music and not destroying his speakers and ears.  Assuming high density music (rock with low dynamic range) running flat out with plenty of clipping, the 50 w amp will consume about 25 W from the power supply. I know as I have done lots of measurements on this. So a max of about 70 W can be expected but realistically a bit less than that as you'd be losing your tweeters with all that clipping, so that comes close to the OP's observations.

I stand by my assertion.

 
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