A Test. How much Voltage (power) do your speakers need? - Page 28 - diyAudio
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View Poll Results: I measured the test tone at:
2 volts or less 141 37.40%
Between 2-5 volts 129 34.22%
Between 5-10 volts 50 13.26%
Between 10-20 volts 21 5.57%
Over 20 volts. 36 9.55%
Voters: 377. You may not vote on this poll

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Old 4th February 2012, 02:10 AM   #271
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Quote:
Originally Posted by a.wayne View Post
Your kidding right. ........!
No he's not kidding. This is one other way you could do the test. Find out at what volume your amplifier clips when presented with a 0dB digital signal. Lets say you've got a digital volume control and you get clipping occurring when it's set to volume 10, but no clipping occurring at volume 9. You have now found out that if you listen to the hifi system at volume 9 and lower that you will NEVER get your amplifier to clip, unless you attach a pair of loudspeakers that the amplifier cannot drive.


Quote:
Originally Posted by a.wayne View Post
On smart phone so responding is well ....


83db works out to 74 db from typical listening position or 80 db stereo best case , 86 db Would then require 8 watt stereo operation , which means 12 db peak would require 128,watts ....
B

50 watt amp just died ............
That is half of the point of the thread though. You're quoting figures for what people are assumed to like listening at. This test actually gets people to listen, rather then using statistics and then go on and calculate the maximum amount of voltage swing necessary for their amplifiers given the maximum possible signal level (0dB digital) that the system could reproduce at their given volume setting. Most people aren't needing that much power, meaning most people probably don't listen as loud as you're thinking they will.
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Old 4th February 2012, 02:12 AM   #272
a.wayne is offline a.wayne  United States
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I meant more efficient Pano

5th,
12 db increase at the amplifier output is not 4 times ......
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Old 4th February 2012, 02:18 AM   #273
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Originally Posted by mr_push_pull View Post
as long as the volume knob is below that specific position, nothing will be clipped, no matter what I listen to, be it pink noise, sine waves, heavy metal or classical.
felt I should add that at the same time it doesn't tell me that any amp which is specified at V^2/4 (V being the clipping voltage) can do the job. some may go tits up if that is specified only on a resistive load. the results stand for my amp only.
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Old 4th February 2012, 02:20 AM   #274
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Originally Posted by a.wayne View Post
I meant more efficient Pano

5th,
12 db increase at the amplifier output is not 4 times ......
It is if we're discussing the output voltage of the amplifier which is what this test is about. We are not discussing output power.

20log(V2/V1) = dB difference in voltages.

20log (4/1) = 20log(4) = 12dB.
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Old 4th February 2012, 02:22 AM   #275
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Originally Posted by mr_push_pull View Post
felt I should add that at the same time it doesn't tell me that any amp which is specified at V^2/4 (V being the clipping voltage) can do the job. some may go tits up if that is specified only on a resistive load. the results stand for my amp only.
Indeed and that is the limit of this test. It does not in any way go about handling the reactive nature of loudspeakers, on the whole this isn't a problem unless you've got a really feeble amp or killer loudspeakers.
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Old 4th February 2012, 02:29 AM   #276
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Hi 5th
Actually I donít see that I am missing anything in fact have spent a good bit of time examining the signals I wish to record and reproduce as well as what is required from the loudspeakers.

The problem is the reproduction system has a peak linear output, the maximum average level (which we hear as loudness all things equal) cannot be anymore than the peak level minus the peak to average ratio or one has instantaneous clipping. The method here is fine until the peak to average envelope exceeds 12 dB.

Add to that the fact that most speakers become dynamically nonlinear once above about 1/8 to 1/10 rated power and the problem seems pretty daunting but hey hifi speakers often donít sound all that real do they?.

The fact is, to reproduce even everyday sounds, requires far more than home stereo speakers can produce. I have B&K sound level meter that can capture instantaneous peaks, just throwing a teaspoon on to a tile floor, produced a peak over 130 dB from about 8 feet. It didnít sound loud at all because your ears donít work like microphones and speakers and everything else in the chain and I guess thatís the problem in part, I am looking at the technical requirements not how short I can come and still sound ok.

To be clear too, the shuttle launch is as dynamic as many good music recordings but what makes it a speaker killer is the spectrum is loudest an octave or more below most hifi speakers low corner.

I am not sure why the great resistance to looking with a scope too, it's not like i am advocating something as heretical as "blind testing", just looking to see instead of assuming because you cant hear anything speacific all is well.
Best,
Tom
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Old 4th February 2012, 02:40 AM   #277
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You've missed the point, again.

The -12dB that Pano has baked into the test has nothing whatsoever to do with peak to average levels. For all intents and purposes Pano could have set the test signal at -1dB and by that logic we've got no dynamic range whatsoever. As I explained above, the test signal is used as a measurement point and everything is scaled around it. The measurement point/signal could be at -100dB -80dB -50dB, it does not matter, the end result, ie the voltage requirement from the amplifier to reproduce a 0dB signal, would be identical each time.
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Old 4th February 2012, 02:42 AM   #278
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Quote:
Originally Posted by Tom Danley View Post
I am not sure why the great resistance to looking with a scope too, it's not like i am advocating something as heretical as "blind testing", just looking to see instead of assuming because you cant hear anything speacific all is well.
I'm not sure everyone here owns a scope. I don't.
instead a sound card can be used, they are good enough for this kind of measurement.
for instance I used the mic input on my laptop and a voltage divider. I couldn't believe how good it was, it's flat from 10Hz to 20k and all the distortion consists of a 2nd order harmonic at -80dB below fundamental (I checked it using my D/A converter which is known to be pretty good). using a RTA with FFT I can clearly see the point where all the harmonics abruptly rise which indicates clipping. just looking at the time display that is barely noticeable but a FFT tells a different story. I'll post some pics tomorrow.
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Old 4th February 2012, 02:46 AM   #279
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Originally Posted by 5th element View Post
You've missed the point, again.

The -12dB that Pano has baked into the test has nothing whatsoever to do with peak to average levels. For all intents and purposes Pano could have set the test signal at -1dB and by that logic we've got no dynamic range whatsoever. As I explained above, the test signal is used as a measurement point and everything is scaled around it. The measurement point/signal could be at -100dB -80dB -50dB, it does not matter, the end result, ie the voltage requirement from the amplifier to reproduce a 0dB signal, would be identical each time.
the reason why Pano chose -12dbfs is that 0 dB would not be appreciated by the woofers given the chosen test frequencies and also your ears would hate it too (I should know as I once fed 20V sines into my speakers). btw I used my speaker's port resonance frequency for the high power test as the cone barely moves at that point. feeling the port output by hand and hearing the windows rattle is quite a show.
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Old 4th February 2012, 02:57 AM   #280
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also, it should be obvious that all this is simplifying things to a point, for instance I don't think anyone pretends that their amp can maintain fixed voltage into any load at any frequency but that is really beyond the scope of the discussion and I think the calculated listening power is accurate enough for the purpose even ignoring the more subtle phenomena.
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