Power consumption versus power output - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 10 Old 01-25-12, 02:31 PM Thread Starter
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Power consumption versus power output

Hopefully this will get enough attention in this section...

How are the two related? As in, if i were to put a Kill A Watt inline with my amplifier and it said 500 watts. Is there any correlation between that and output? I'm sure efficiency plays into it or something. Just wanting to learn a little about it..
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post #2 of 10 Old 01-25-12, 02:35 PM
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Re: Power consumption versus power output

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black_z wrote: View Post
Hopefully this will get enough attention in this section...

How are the two related? As in, if i were to put a Kill A Watt inline with my amplifier and it said 500 watts. Is there any correlation between that and output? I'm sure efficiency plays into it or something. Just wanting to learn a little about it..
You may not get a good correlation between AC usage and the actual audio wattage output.

Most class A/B amps are not that efficient.

I've played with a Kill-A-Watt and you'll probably get mixed results.


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post #3 of 10 Old 01-25-12, 02:39 PM
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Re: Power consumption versus power output

Yes, efficiency. The best class A/B amps are only up to about 60% efficient. So if you were really delivering 100Wrms to the load, the AVR would likely be drawing 166W+ at the wall.

The content of the material your amp is playing makes a big difference as well. Only a constant tone would draw a constant amount of power. Music is essentially a random load.


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post #4 of 10 Old 01-25-12, 02:50 PM
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Re: Power consumption versus power output

What's even more confusing is if you're playing content at say, 80-90db, you're using 1 audio watt........ so even with 3875 watts on tap (4 Emotiva amps) - the wattage may read nearly the same as it does at dead idle.

It requires a little work to know what the actual audio output is at any given time..


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post #5 of 10 Old 01-25-12, 02:54 PM
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Re: Power consumption versus power output

Precisely. Transients and bass-heavy content aside, they say that even louder listening levels don't rountinely break 10W.

In the DIY speaker world, 5-10W resistors are extremely common in passive crossovers. I don't think that I've ever heard of on burning up or failing.


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post #6 of 10 Old 01-25-12, 03:14 PM Thread Starter
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Re: Power consumption versus power output

I guess I'll experiment with it some and see what I can find out...
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post #7 of 10 Old 01-25-12, 07:23 PM Thread Starter
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Re: Power consumption versus power output

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fusseli wrote: View Post
Yes, efficiency. The best class A/B amps are only up to about 60% efficient. So if you were really delivering 100Wrms to the load, the AVR would likely be drawing 166W+ at the wall.

The content of the material your amp is playing makes a big difference as well. Only a constant tone would draw a constant amount of power. Music is essentially a random load.
Yeah, I'll test with sine wave just to keep it consistent.
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post #8 of 10 Old 01-26-12, 11:14 PM
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Re: Power consumption versus power output

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Yeah, I'll test with sine wave just to keep it consistent.

Like many people have said already...


Still does not reflect real music reproduction, your test will not be accurate at all, music is not a 1khz sine wave but a mix of freq. from 30hz ish to 15 khz ish, just like the forever going debate about RMS power Vs instant peak power available.......

A class is about 50% so for 100 watts out you will need about 200 in, AB class about 60 to 70%, G,H,I class somewhere in the 80% to 85% and D class 90 to 95% efficient.

Again if you take a good iron amp vs switching power supply amp for the same class you will start a debate all by itself, many will swear that the good old iron will kick more power in the lower hz but pull more amps eternal debate etc etc,IE Crown VZ5002 vs ''insert your SMPS amp model here''

To be honest do you really care about amplifier(ssss) power consumption? if you do you are in the wrong hobby if you cannot afford the power bill, me i don't as long the amp does what it is design for, plus because with a 200 amps panel in the house i'm no where near short, i think anyway my 2 cents.
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post #9 of 10 Old 01-27-12, 03:18 PM Thread Starter
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Re: Power consumption versus power output

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kouack wrote: View Post
Like many people have said already...


Still does not reflect real music reproduction, your test will not be accurate at all, music is not a 1khz sine wave but a mix of freq. from 30hz ish to 15 khz ish,
No one is talking about music reproduction. At least not me...

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kouack wrote: View Post

To be honest do you really care about amplifier(ssss) power consumption? if you do you are in the wrong hobby if you cannot afford the power bill,
Again... not sure where you're getting this. No one even hinted about consumption costs and me not being able to afford my power bill! lol

Just wondering what the Kill A Watt is gonna show for consumption, versus output.
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post #10 of 10 Old 01-27-12, 04:06 PM
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Re: Power consumption versus power output

Take some dB vs. kill-a-watt measurements and make a graph?


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