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View Poll Results: I measured the test tone at:
2 volts or less 133 38.11%
Between 2-5 volts 118 33.81%
Between 5-10 volts 44 12.61%
Between 10-20 volts 21 6.02%
Over 20 volts. 33 9.46%
Voters: 349. You may not vote on this poll

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Old 5th February 2012, 01:17 AM   #351
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Quote:
Originally Posted by phivates View Post
Did Tom say .5V in post #336? Is there more to this poll?
Tom said...

Quote:
I did the test, with 101dB 1w1M sensitivity speakers it takes about ˝ VRMS mid band sine to reach a very decent loudness.
Now I am going to be very pedantic about this because it's necessary, but Tom says he needed 0.5Vrms with a mid band sine wave to reach a very decent loudness. Where I'm going to get nit picky is this...

1) Did Tom play his most dynamic piece of music at the loudest volume he would ever play it at, THEN, keeping the volume control in the same place, play Pano's -12dB sine wave test and get 0.5Vrms or...
2) Did Tom play only a sine wave and set the level based off of how loud the sine wave was?

If he did 2, which is what he's implied by saying he needed 0.5Vrms with a mid band sine wave to get a decent loudness. Then he's not done the test correctly.
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Last edited by 5th element; 5th February 2012 at 01:35 AM.
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Old 5th February 2012, 01:27 AM   #352
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Tom,

what I'm still trying to understand is why are you trying to make this seem so complicated. let me try another way of putting it.
I found that using 0 dBfs sines, my amp is just below clipping at an output voltage of 22 volts, into a 4 ohm resistive load at any frequency (20Hz-18kHz). hopefully it behaves well into my speakers which don't go below 4.4 ohm at any frequency (obviously I won't test that with sines into my speakers).
with the volume pot set at the position that gives 22V at speakers inputs, I found that 99% percent of my recordings sound loud enough for my taste (some even too loud). my normal listening level is at or below 9V.
now, assuming that you're not telling me that I should be listening at higher SPLs (we're talking about my room, my stereo, my ears and my taste after all) what part of the above you disagree with and why?

also, I'd like to add that I still believe that real-time FFT analysis is even more telling of clipping, compared to a temporal view. at the onset of clipping high order harmonics suddenly show and begin to rise at a high rate compared to the fundamental as the clipping advances. for instance when using a 1k tone, with my amp the "just clipping" state is barely visible on a waveform while the FFT suddenly starts to resemble a comb.

and to everyone.
I find what one previous poster said very true. after I got my first serious speakers I noticed that I started to listen at higher SPLs. the first time I became aware of it was when one friend of mine was at my home. he was sitting maybe one meter away from me and I needed to raise my voice (almost shout) so he could understand what I was saying. until I did that neither of us noticed how loud the sound was.
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Last edited by mr_push_pull; 5th February 2012 at 01:48 AM.
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Old 5th February 2012, 01:56 AM   #353
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Quote:
Originally Posted by 5th element View Post
Tom said...

Now I am going to be very pedantic about this because it's necessary, but Tom says he needed 0.5Vrms with a mid band sine wave to reach a very decent loudness. Where I'm going to get nit picky is this...

1) Did Tom play his most dynamic piece of music at the loudest volume he would ever play it at, THEN, keeping the volume control in the same place, play Pano's -12dB sine wave test and get 0.5Vrms or...
2) Did Tom play only a sine wave and set the level based off of how loud the sine wave was?

If he did 2, which is what he's implied by saying he needed 0.5Vrms with a mid band sine wave to get a decent loudness. Then he's not done the test correctly.
I think that we really need to be nit picking on this because some readers might get the wrong idea and still be convinced that they need kilowatt amps even with well behaved speakers with medium sensitivities and small/medium listening rooms.

I reread the first posts and I think I know what's going on. in the first post from this thread Pano wrote:
From that you can determine how much power you need.

I think Tom (and maybe others) stopped reading there and hence the confusion. there's simply no other explanation.
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Old 5th February 2012, 01:58 AM   #354
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Default clipping

Is this thread about what we listen to or about what we could do? I think Pano just wants us to look at what we really do. Clipping is do be avoided at all cost in the hi fi world as I understand it...but I'm an old fool. Almost 66. I'll post my measurement tomorrow
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Old 5th February 2012, 02:00 AM   #355
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Quote:
Originally Posted by 5th element View Post
And with all due respect, neither of you have understood this test.

There isn't supposed to be a reference that's the point. No one knows how loud it is in decibels because they do not need to.
Make that three of us.......... I size amps based on dynamic headroom requirements and Pano's way is basically the way I would size a 70V distributed system where fast transients are moot, so with nothing functioning around here to measure, all I can use is a thought experiment.

I'm sitting 1 m away from a 1% eff., nominally 8 ohm speaker [~92 dB/W/m] and my loudest comfortable SPL is 85 dB and I want an amp that will ensure it won't clip on 105 dB peaks.

What do you calculate doing it your way and what formula did you use to calculate the theoretical voltage level at 85 dB?

TIA,

GM
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Old 5th February 2012, 02:16 AM   #356
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Originally Posted by GM View Post
What do you calculate doing it your way
obviously a totally unrelated number because no-one said that the test should be done at an average level of 85 dB. maybe I did mine at 80, maybe I did it at 95, I don't know because I don't have a SPL meter.
I think you misunderstood the test too as it's not about what should be going on but about what is actually going on. all you're saying is "your test is wrong because your listening level is too low".
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Old 5th February 2012, 02:40 AM   #357
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I've said nothing of the sort! Please don't put words in my mouth!

Regardless, it shouldn't be unrelated! That's the point! Instead of a voltage reading, I've given what it represents. I've already calculated what I believe are close enough values, but I want to see what Pano's way comes up with.

GM
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Old 5th February 2012, 03:11 AM   #358
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Thanks for your response GM this is actually a very good example of what this test isn't about and can hopefully serve as a good example for those who perhaps don't quite get it.

This test doesn't take into consideration your theoretical max SPL requirements, ie requirements written on paper. It also doesn't take into consideration the sensitivity of your loudspeakers as per their specification.

What we're doing here is taking the most dynamic piece of music you have and playing it at the maximum volume you would ever play it at. This basically determines the maximum volume you would ever want your hifi to reproduce given your most demanding piece of music and now we know what that volume is as per the setting on your volume control.

This is rather basic in its idea, no we don't know what that volume is in dB, but we know that with your musical tastes and listening habits that you will never turn your hifi up beyond that setting on the volume control.

Now the one assumption that we are making, for the rest of this test to be valid, is that most people will do their listening on a CD player, SACD player, DVD audio player, PC + external DAC etc. That is a digital source which has a max possible signal level fundamentally baked into its specification, which is 0dBfs. The output of digital sources is usually set to = 2Vrms as per a single ended output when the recording reaches 0dBfs but this isn't necessary for the test to work. What's important is that there's a fixed defined absolute ceiling baked into digital reproduction that you cannot exceed.

Now, we've set the volume control to the maximum that the listener will ever listen to their system at and we've also got a source that has a fundamental maximum amplitude that it can reproduce baked into its specification. This in itself allows us to determine a maximum voltage output on the amplifier, if you will, for their maximum volume setting.

After having set the maximum volume, Pano has provided a sine wave with an output equal to -12dBfs at a frequency that most standard digital volt meters will be capable of measuring accurately. You now play this through your system and measure the voltage that your amplifier outputs with your multimeter. Lets say it equals 5 volts rms.

Pano chose a -12dBfs signal over using a 0dBfs signal to protect your speakers and to ensure that your amplifier isn't going to clip when playing the test signal. We are really interested in the voltage the amplifier outputs with a sine wave played at 0dBfs but this is a tall order for anyone's system when its set to the 'loudest you will ever use it at'. So we use a -12dB signal.

Now this isn't a problem of course because scaling that measured 5Vrms up by 12 decibels, to show what the amplifier would really output given a 0dBfs signal, is a trivial task and is accomplished by multiplying the voltage level by 4. In this case we will end up with 20Vrms.

After having done this we now know, that given your previously set maximum volume setting on your hifi, that when your digital source is replaying the maximum signal that it can ever output, that this translates to the amplifier having to swing 20Vrms.

Most decent hifi amplifiers come with an 8 ohm resistive load specification for the amount of watts they can output. Lets say the amplifier is specified at being able to produce 100 watts into 8 ohms. Knowing this we can back calculate what voltage the amplifier is capable of swinging to produce those 100 watts. In this case it's 28Vrms or 40 volts peak/80 volts peak to peak.

Knowing this we can now see that (providing the amplifier doesn't go into current limiting) the amplifier is perfectly capable of reproducing the 20Vrms maximum that it would ever be called on to reproduce.

From this value you are now of course free to calculate, given the max calculated voltage drop that the amplifier will supply to their terminals, the maximum peak SPL that your loudspeakers are likely to produce, but it is only necessary should you want to know.

The point here is that we've taken the persons system to the max it will ever be taken to and then shown, that when called upon, that their amplifier will not clip when their DAC outputs its maximum signal level equal to 0dBfs in a digital recording.

The reason why Pano created this thread and the poll was to see how many volts (and then potentially watts) people were actually needing their amplifiers to be able to swing to reproduce their most demanding pieces of music at their loudest volume setting.

You see the target figure of 105dB for peaks batted around all over the place as if it's a goal you should want to arrive at, as can be seen however, most people who've done the test are probably not reaching anywhere near 105dB on their peaks. I know I don't even though the system is capable of doing it and capable of doing it cleanly too.
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Old 5th February 2012, 03:16 AM   #359
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Quote:
Originally Posted by rongon View Post
To get that figure of 6W per side, did you figure on peaks being -3dB down from 0dBFS? I thought the numbers meant that I'd want a 12W per ch amp, to be able to deliver 12 watt peaks...
I used 0dB as peak. If you need 12 watts peak, then an amp that can do 6 watts RMS without clipping or bad distortion can give you those 12 peak watts without clipping or bad distortion.

Remember the peaks of a sine wave are 3dB higher than its RMS voltage. That means twice the power (1.42 x voltage).
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Old 5th February 2012, 03:20 AM   #360
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Oh hang on.....I thought this thread about a simple test everyone with a VM could carry out.

What a fool I am

The OP must have been asking if this was a valid test and how it could be improved

Pano, 5th Element, I thank you for your efforts and, to be honest, cannot believe the keystrokes you have put in just trying to keep this simple test thread on track. Its pretty dead though chaps. Any earnest mind has to battle through 30 odd pages of turd for a just a handful of measurement posts.

To the obtuse, argumentative & downright wilful, your job is done (the thread is basically a wreck for the rest of us) and if you answer this to defend yourself, you merely pin the above to your chest as a badge.

The main measurements provided here have been those of character and I would say Pano & 5th Element come up shiny
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