A Test. How much Voltage (power) do your speakers need? - Page 27 - diyAudio
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View Poll Results: I measured the test tone at:
2 volts or less 155 37.80%
Between 2-5 volts 139 33.90%
Between 5-10 volts 52 12.68%
Between 10-20 volts 25 6.10%
Over 20 volts. 39 9.51%
Voters: 410. You may not vote on this poll

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Old 4th February 2012, 02:48 AM   #261
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Originally Posted by a.wayne View Post
The test maybe flawed in some way pano , it's impossible for those with avg sensitivity speakers to get any high resolution sonics from 25 watts , 90 + db yes with limited dynamics .....

I will give it ago tonight .......
yes, maybe not realistic levels with full scale orchestra. but nevertheless, with my 83 dB w/m speakers 20-30W is pretty much party level and with heavy metal for instance I can't understand a person sitting next to me unless he/she shouts. also mind that in Europe the average room might be smaller than in US and that could be a factor too.
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Old 4th February 2012, 02:50 AM   #262
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Your kidding right. ........!
enlighten me...
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Old 4th February 2012, 02:52 AM   #263
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Originally Posted by a.wayne View Post
Ok ,

Fly in the ointment, the test tone frequency , it's at that point where most speakers are very sensitive . IMO it would be best if the test tone was at center frequeny , 1k ....
who said I was using Pano's test frequencies?
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Old 4th February 2012, 02:56 AM   #264
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Originally Posted by Tom Danley View Post
I think there is some confusion too on the title of this since what is needed depends on many things and in spite of many attempts to differentiate loudness from dynamic range I have been unable at least for many. Feels a lot like the old days trying to explain extension is not the same as loud bass haha.
This is not the case here. Everyone is aware of the difference between dynamic range and loudness. The 'loudness' in this test is subjective and is what is used to determine the point at which one sets their volume control. The maximum of the dynamic range is defined as being 0dB digitally and is used to determine whether or not your amp will ever clip given the largest dynamic possible of the digital format.

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Originally Posted by Tom Danley View Post
Lets say one does find it takes 2Volts RMS to produce a sine wave test signal like here as loud as you would care to have it. With a sine wave, all you need is an amplifier than supply that 2VRMS and no more.
So letís say your amplifier can swing the suggested 4X or 8Volts RMS and all is well.
Here is the part that you're missing.

Quote:
Lets say one does find it takes 2Volts RMS to produce a sine wave test signal like here as loud as you would care to have it.
No one is using a sine wave as a signal by which to set the volume control, the sine wave is an objective 'test', 'measurement' or 'control' signal only.

I think Pano's choice of sine wave signal level could perhaps be what's creating the confusion. For want of a better explanation, because I cannot read his mind, Pano chose to use a signal at -12dB or whatever because this wouldn't put stress on your system and would be unlikely to cause your loudspeakers to be destroyed. The less complicated way to have done this would be for him to have used a sine wave played at 0dB but that could have been destructive.

One listens to a piece of music. For the sake of this test it would make sense for someone to use their most dynamic piece of music with the largest average to peak ratio. They then set their volume control to the loudest that they would ever listen to this piece of music at.

After having done that they play Pano's sine wave at -12dB and then take a measurement on their volt meter of the amplifiers output. Lets say it reads 5Vrms.

Now we used a test signal that was 12dB below the maximum possible for digital, so we now compensate for that by multiplying the voltage 4 times as 20log(4) = 12dB. Having multiplied this by 4 we end up with 20Vrms.

What this tells you directly is that if you were to feed a 0dB sine wave through the system, the output on your amplifier would = 20Vrms.

20*20 = 400 / 8 = 50. Or 50 watts into an 8 ohm load. The users amplifier is capable of 150 watts into an 8 ohm load, so providing the loudspeakers are an easy enough to drive 8 ohm load, we know that the amplifier isn't going to clip when the system is confronted with a 0dB signal at the given volume.

What we are interested in when doing this test is seeing if the amplifier clips when presented with a 0dB signal at your 'loudest ever' position on the volume control.

We could have scaled up the digitally created sine wave by 12dB initially and used this as the test stimulus but chose not to so as to protect the system and then account for this later on.

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Originally Posted by Tom Danley View Post
Now, one puts in AES pink noise at 2VRMS, to supply this signal, one needs an amplifier than can swing 4VRMS because this signalís envelope has a 6dB peak to average ratio over the sine. Use pink noise from Smaart or any RF test gear used in audio and one finds about 10dB peak to average ratio in the envelope. This test signal requires an amplifier than can deliver 6.6VRMS in order to produce the 2VRMS signal.
The trouble here, as you should now see, is that if we scale up the pink noise appropriately, like we could have done with the sine wave digitally instead, that the pink noise will now clip digitally as it will try to go above 0dB. The amplifier though will reproduce the digitally clipped signal faithfully however as it wont clip when 0dB is reached and this is what we were trying to find out originally.

If ones amplifier is free from clipping when a 0dB signal is sent through the hifi system at the loudest volume you will ever use, then it does not matter what signal you try and feed it, fireworks or shuttle launches. The amplifier will not clip.

Now lets say I did the test again, but this time I went about it using the shuttle launch. I set the volume at the start so that the level of the talking people is realistic. Then the shuttle launches, then my amplifier clips and the my loudspeakers explode. Yes, no one is trying to say this won't happen, of course it will. But no one here is trying to reproduce a shuttle launch accurately. They are trying to reproduce their most demanding piece of music at the maximum volume they will ever listen to it at. They then do a test to see if a 0dB digital signal will clip their system at this volume and find that it won't. Now they know that their system won't clip, ever, given their taste in music and listening habits.
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Old 4th February 2012, 02:58 AM   #265
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Originally Posted by mr_push_pull View Post
yes, maybe not realistic levels with full scale orchestra. but nevertheless, with my 83 dB w/m speakers 20-30W is pretty much party level and with heavy metal for instance I can't understand a person sitting next to me unless he/she shouts. also mind that in Europe the average room might be smaller than in US and that could be a factor too.

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 ............

Last edited by a.wayne; 4th February 2012 at 03:00 AM.
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Old 4th February 2012, 02:59 AM   #266
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Originally Posted by mr_push_pull View Post
I'm looking at it in a different way.
I measured the voltage where my amp starts clipping by analyzing the output waveform. that is with a full scale (0 dBfs) sine input. I remembered the volume knob position where that happens and therefore I know that 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.
if I turn it past that position I know that sooner or later clipping will happen. simples.
YES! You've got it!
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Old 4th February 2012, 03:03 AM   #267
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Originally Posted by 5th element View Post
If ones amplifier is free from clipping when a 0dB signal is sent through the hifi system at the loudest volume you will ever use, then it does not matter what signal you try and feed it, fireworks or shuttle launches. The amplifier will not clip.
obviously, a.wayne disagrees.
if I get it correctly, he's saying that although for a specific volume setting and with 0dBfs sine wave an amp won't clip at any frequency, with that same volume setting the same amp will clip with certain signals.
I'm still not sure what's the source of the confusion that I somehow have the impression that part of it arises from the fact that many seem to share this view.
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Old 4th February 2012, 03:03 AM   #268
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YES! You've got it!
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Old 4th February 2012, 03:06 AM   #269
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Originally Posted by a.wayne View Post
Fly in the ointment, the test tone frequency , it's at that point where most speakers are very sensitive
Really? Speakers are "most sensitive" at 120Hz or 240Hz? Are you sure about that? And even if they were, what difference would it make? Are you sure that you understand how the test works?
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Old 4th February 2012, 03:09 AM   #270
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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 ............
not sure I get it. my listening position is at about 2 meters from each speaker. as I said, small room.
later edit: it may also mean that I'm getting old. somehow the one zillion dB at the club I can take but at home I think 90 dB is party level.
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Last edited by mr_push_pull; 4th February 2012 at 03:12 AM.
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