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Merit in measuring @ 1 watt (first watt performance)?

Chromatischism

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#1
I've seen this idea thrown around at times - is there merit in including a measurement of how clean an amp can produce sound at very low levels, such as some of the transients in music or when listening at low volume?

Also, I have a Denon X4500H and a Hypex NC252MP if anyone has specific info about those.
 

Matias

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#3
The current 5W in 4 ohms is very good, very representative. Most people would be surprised how little power is needed to play reasonably loud in most systems.
 

Foxxy

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#4
The first Watt is actually the most important Watt in any amp. Just take a SPLmeter an measure how loud you actually listen most of the time. Often it's not even 80dB average which means you aren't even using much more than a Watt to listen to stuff. Turn it down just a few dB more and not even your transients will use a full Watt.
A Watt is a lot more than most people think, and that's when dealing with lower efficiency speakers.
 

amirm

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#5
Not sure at what level things like crosstalk are taken at.
It is 5 watts but doesn't make much difference since what is shown is a ratio.
 

amirm

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#6
Most amps have more noise at 1 watt than distortion. So the measurement becomes that of noise. By going up to 5 watt, then there is enough signal to push the noise down and let the distortion contribute as well.

In this day and age, speakers are using small enclosures, making them pretty inefficient. One watt as a result is not an indicator of real life usage.
 
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Chromatischism

Chromatischism

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Thread Starter #7
The current 5W in 4 ohms is very good, very representative. Most people would be surprised how little power is needed to play reasonably loud in most systems.
5 watts gets me 85 dB with only 88 dB sensitive speakers. That's pretty loud. I'm talking about what an amp does when it's asked to produce sounds that require only 1 watt. That would be about 80 dB for me, which is music listening level. That assumes the amp has no headroom, so subtract 3 dB to assume you're maintaining some headroom.

https://www.crownaudio.com/en/tools/calculators

That becomes a fraction of a watt if someone uses higher sensitivity speakers.
 

Blumlein 88

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#8
If you listen at reference levels averaging mid 80 db spl, you may be averaging around a watt or two, but 20 db headroom means some momentary amounts of 100 watts or so.
 
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Chromatischism

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Thread Starter #9
Right. I'm definitely using more than a watt for movies. But most music doesn't have me going from 85 dB to 105 dB. I'd turn that down or run out of the room :)
 

NTK

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#10
The issue is a little bit more subtle. There is a "problem" with measuring power amp output using single tone sine waves. Music is not a single tone sine wave. The important difference is in the crest factor. Single tone sine waves has a crest factor of 3 dB, which means the V_peak is 1.414 * V_rms. Music typically has a crest factor of >12 dB (see below), which means when outputting the same average power, V_peak is >4 * V_rms.

The implication is that, if you are listening to music at the 80 dB SPL at 1 W average power (as in your earlier example), your amplifier will need to have the voltage output capability to produce an equivalent of >8 W when tested with a single tone sine wave. Add another 10 dB headroom for program peaks, and you will need an amplifier capable of delivery unclipped power of >80 W (as measured with single tone sine waves) when your listening level only requires an average power of 1 W.

CF.JPG
 
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