Measuring power draw from speakers? - Page 2 - AVS Forum
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post #31 of 42 Old 10-26-2013, 07:07 AM
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Quote:
Originally Posted by OllieS View Post

This is the thread I found on DIYaudio forum :

http://www.diyaudio.com/forums/multi-way/204857-test-how-much-voltage-power-do-your-speakers-need.html

What do guys think of this test?

It's fine if what you want to know is the voltage at the speaker terminals and, as Arny explains, that may be all you need. I only suggested that he go one step further and measure current as well to get to actual power, which is what he asked for. The method for setting the volume control isn't really a calibration. It is setting the volume by ear. I think that is probably fine for home audio purposes. The OP isn't going to develop some sort of world wide specification. He's just assuaging his curiosity.
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post #32 of 42 Old 10-26-2013, 07:11 AM
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After I run Audyssey, I then turn on my volume limit so it never can go past 0db reference on main knob in my HT 11.3 and family room 5.1 setup.
Side bar is how many people really listen above reference volume?


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post #33 of 42 Old 10-26-2013, 07:15 AM
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Like I said, I personally don't go past 18 watts even on peaks and that is with the volume control set at -10 which is as loud as I can listen to a movie without discomfort. But understand that I wear ear plugs in movie theaters. I can't listen to that much loudness comfortably there either.
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post #34 of 42 Old 10-26-2013, 06:12 PM
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In this thread someone said they used a Kill-A-Watt to measure....would that work?

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post #35 of 42 Old 10-26-2013, 06:35 PM
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Quote:
Originally Posted by lovinthehd View Post

In this thread someone said they used a Kill-A-Watt to measure....would that work?
Not very well. It's accuracy will have been designed for slowly changing mains levels at one frequency and voltage, quite the opposite of audio.
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post #36 of 42 Old 10-27-2013, 07:51 AM
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Quote:
Originally Posted by arnyk View Post

IME the Simpson watt meters have very poor frequency response by audio standards.

http://www.kjq.us.com/images/SIMPSON_880_WATT_METER.pdf

"±0.5% from 54 Hz to 66 Hz Sine Wave"
What I have is a set a fixed wattage meters not he one you listed

I have not done a lot lot of testing-but have found that they are the closest easiest way to get a good IDEA of the wattage going to a speaker.

As has been stated the "actual" wattage varies greatly depending on the freq-time it was measured etc.

You cannot say that "X wattage is going to my speakers"

At best it would be a wide range over an average time.

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post #37 of 42 Old 10-27-2013, 07:54 AM
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Quote:
Originally Posted by OllieS View Post

I think this topic is a lot more complicated than I anticipated. What I'm asking just can't be done by the laymen, or at reasonable cost. That's unfortunate, because I'm sure lots of people would like to know how much power is being used on their systems. Or perhaps I'm the only one... I just know that after reading all the comments in my previous threads, I feel a lot more cautious now than I was before.

I think I read something on the DIYaudio forum about a test concerning maximum voltage required by the speakers, but I don't know if that would be relevant to what I'm asking.

Look at it this way-play a piece of music and watch a VU or other "power" meter. Now give me ONE number that it was measuring? You can't because it is jumping all over the place.

And remember that a 3dB change is TWICE or HALF the wattage. a 10dB change is 10 times the difference.

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post #38 of 42 Old 10-27-2013, 07:55 AM
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Quote:
Originally Posted by lovinthehd View Post

In this thread someone said they used a Kill-A-Watt to measure....would that work?

The Kill-A-watt measures the AC power drawn by the amplifier or other appliance, which is only loosely connected to audio power delivered to the speakers. As others have pointed out they are also averaging-reading devices and wouldn't accurately follow a varying audio signal.

If someone devised a Kill-A-Watt for speakers, that would be pretty cool, but a very different device.
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post #39 of 42 Old 10-27-2013, 08:06 AM
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Quote:
Originally Posted by mtbdudex View Post

Back in the day there would be amp display meter on dedicated amps, logarithmic scale, been a while since I saw those.

Here is a thread I found while searching google ""
http://www.tnt-audio.com/shows/burning_amp2012_e.html


between what Ivan posted, who does this for a living, I'm still curious your drive and desire to have this data?

ahh, found them! Just get these and be happy reading them!
I am not aware of any amplifier that has ever had a WATTAGE meter on it. At best it was a VOLTAGE meter with a difference scale for the different impedances.

But that ASSUMES that the speaker is a 8 ohm (or whatever) at all freq-which it is FAR FROM.
The rating is simply a "normal" number that some of the lowest points on the IMPEDANCE CURVE happen to be close to.

Just look at the impedance curve of any loudspeaker and see how much it varies. So given the same voltage input (what the meters are measuring) the WATTAGE will be very different at different freq.

Now LUCKILY if you are measuring the voltage (and can do that accurately) and assuming the rated impedance is around the lowest impedance then that would be the maximum wattage that would be going to the speaker. NOT the ACTUAL (which is less at some or most freq), but it could be considered worse case.

And I assume that the whole idea is to get an idea so as to not overpower the loudspeakers-but that is ASSUMING that the published wattage ratings are legit and accurate.

But remember that the wattage ratings are based on test tones (or the marketing dept wild ideas of what would sell better) that are "standards" so as to simulate "music".

But there are many different types of music-that have very different freq responses- crest factors etcs. That can greatly affect the actual "power" going to them.

The nice thing about standards is that there are so many to choose from.

A loudspeaker tested using one standard will have a different set of numbers as tested using another standard. So the actual "wattage" numbers can vary.

Such as if you are playing heavy dance music the loudspeaker will be working much harder than if playing jazz-even though the max level on the "wattage or level" meter would be the same-but the AVERAGE HEATING level is quite different. And THAT is what kills most loudspeakers. HEAT OVER TIME. You have to establish BOTH of those numbers together to make any real sense

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post #40 of 42 Old 10-27-2013, 01:45 PM
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I hope this isn't too far off topic but I've wondered for awhile the accuracy of clipping indicators on amps. Its been discussed in this thread how some meters are too "slow" to capture short durarion peaks. Do clipping indicators have similar limitations? Is there a certain duration or "amount" of clipping before clipping is indicated? Could an amp have very brief clipping without being indicated?
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post #41 of 42 Old 10-27-2013, 02:19 PM
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Quote:
Originally Posted by ironhead1230 View Post

I hope this isn't too far off topic but I've wondered for awhile the accuracy of clipping indicators on amps. Its been discussed in this thread how some meters are too "slow" to capture short durarion peaks. Do clipping indicators have similar limitations? Is there a certain duration or "amount" of clipping before clipping is indicated? Could an amp have very brief clipping without being indicated?
The answer is "it depends".

Some are simple voltage indicators-which means if they are set for clipping at 8 ohms-then there will more clipping when used with lower impedances.

HOWEVER-our ears can "tolerate" a good bit of distortion before it becomes noticable. Some people are more sensitive than others.

An old story from decades ago was with the Crown DC300-THE serious amp back in the 70s for PA and HI FI alike.

The original amps had no indicators. THen they came out with a model that would detect any difference (distortion) between the input and output signals and an LED would flash.

People started saying that the new amps were not as loud as the old amps.

THe joke was "How do you make a new Crown louder?" Put a piece of electrical tape over the LEDs. Because people would look at the lights instead of using their ears.

I have done some blind testing where distortion was introduced without changing the levels. It was actually embarassing.

It is real easy to get hung up on some things and completely miss the big picture.

Such as looking at distortion specs on a piece of electronics and thinking it will make a difference in their sound. Yet they never look at (or can even find) the distortion specs on the loudspeakers.

Loudspeakers have distortion several magnitudes (Think thousands of times higher) than the electronics in front of them.

So the thing with the highest level of distortion is simply ignored
Does that make sense? But yet people "brag" on how low the distortion is-YEAH RIGHT! Let's talk the WHOLE system-not just one piece of gear.

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post #42 of 42 Old 10-27-2013, 03:04 PM
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Quote:
Originally Posted by ironhead1230 View Post

I hope this isn't too far off topic but I've wondered for awhile the accuracy of clipping indicators on amps. Its been discussed in this thread how some meters are too "slow" to capture short durarion peaks. Do clipping indicators have similar limitations? Is there a certain duration or "amount" of clipping before clipping is indicated? Could an amp have very brief clipping without being indicated?

Not all clipping indicators are made the same. The better ones actually compare the input and output of the amp and give an indication when they are too different. This isn't necessarily rocket science or costly. For example the clipping indicator that QSC (a well-known pro power amp manufacturer that you may know about) uses has six parts that cost less than a dime each. In my testing it starts giving an indication when distortion rises to about 0.02%.
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