A Test. How much Voltage (power) do your speakers need? - Page 39 - diyAudio
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View Poll Results: I measured the test tone at:
2 volts or less 141 37.50%
Between 2-5 volts 129 34.31%
Between 5-10 volts 49 13.03%
Between 10-20 volts 21 5.59%
Over 20 volts. 36 9.57%
Voters: 376. You may not vote on this poll

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Old 5th February 2012, 06:15 PM   #381
GM is offline GM  United States
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Quote:
Originally Posted by Pano View Post
Hard to say GM, the test isn't designed that way. Please see 5th Element's post above.
OK, I didnít know if there was a way to theoretically calculate a voltage level from knowing the SPL and specs of the test tone to arrive at a comparison between your way and the near century of proven calculated SPL way.

TDís the one to answer this as Iíve never taken the time to learn much about recording, though the > [clipped] +30 dB transients that some CDs have implies that it be at least at Ė30 dB if Iím understanding how it works and while pink noise most closely mimics music AFAIK, ergo seems the proper signal, I donít have enough experience in these types of measurements to know other than to try it if I could.

Again, I have no functioning HIFI or HT system for years now to measure, hence the hypothetical problem and donít care about the computer 2.1 way system; I know itís a gutless POS and could never handle much in the way of dynamics no matter how powerful, etc., the signal chain.

Plus, Iíve nothing to measure with unless the mic from my fried dbx RTA will work accurately enough with the motherboardís sound card. Can you even use it to measure with while itís driving the source?

Anyway, as you can see, Iím way behind the times on some of this stuff and my response to 5th covers my concerns/reservations that based on experience I donít believe I need a measurement to question.

GM
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Old 5th February 2012, 06:34 PM   #382
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Originally Posted by mr_push_pull View Post
with all due respect, it's you who doesn't understand that it's basically what you're saying only put another way.
Well, apparently you didnít understand what/why I was attempting nor my first response to you, so not much point in us wasting any more time with each other.

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Old 5th February 2012, 06:34 PM   #383
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Thank for the reply GM. I'm starting to see where the confusion comes from. Maybe a good number of people just don't have much experience with digital recordings.

Digital recordings have absolute values because the recording is really only abstract. It's just a pile of numbers - no magnetic tape, no grooves, no wire recorders. Of course those numbers are stored on something, but that "something" could be just about anything, even a stack of punch cards. It's still exactly the same recording.

Those absolute values mean that there is an absolute maximum signal - it's called 0dB (full scale). All other values must be below that. That 0dB becomes our reference - we know absolutely where all other values are in relation to the 0dB level. My test tone has an RMS value of 12dB below that absolute maximum. Because it's a sine wave, its peaks are 9dB below 0dB. (3dB higher than the RMS value).

CDs always have an absolute value of 0dB, the peaks can never be higher that than, no matter how it's recorded. The peaks may be clipped, but those clipped peaks are all at 0dB. CDs can be mastered with average levels just about anywhere (unfortunately). It does not matter if the music is recorded 18, 10, 35, or 16dB below 0dB, 0dB is always the maximum level. Not every track hits 0dB on the peaks, but many do. And I've never seen a CD without 0dB peaks somewhere, on one or more tracks.

Once we are in the digital realm it becomes easy to measure and calculate other values from that.
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Old 5th February 2012, 06:41 PM   #384
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GM, it is as Pano has said before, you haven't quite understood the concept of the test and how it functions. You can use it for any system with a digital source be it for HT or music. All you have to be aware of is any gain that the system could add outside of the digital 0dBfs maximum. In this way it's similar to running the test for an actively crossed pair of loudspeakers, in that you need to run the test tone at the frequency that corresponds to the point of maximum gain on your active filter.


Quote:
Originally Posted by GM View Post
OK, I didnít know if there was a way to theoretically calculate a voltage level from knowing the SPL and specs of the test tone to arrive at a comparison between your way and the near century of proven calculated SPL way.
Here's the problem. Pano's test bares no resemblance whatsoever to the 'century proven calculated SPL way', the two methods aren't even competing with one another because they are set out to do two completely different things. Pano's test is not about calculating an end SPL figure, nor is it a method of coming up with a way to see if you've got enough amplifier voltage swing given a target SPL figure based on your loudspeakers sensitivity.
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Old 5th February 2012, 06:50 PM   #385
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Thanks for the test Mooly.
Quote:
Originally Posted by Mooly View Post
I then went back and ran Panos 220 Hz track at this same volume setting and measured 3.7 volts RMS.
That contrasts with your 5V RMS measurement when you set the level by ear, right?

From the two pink noise at 85dB tests so far we see that I hit the same volume setting and you actually set yours 2.6dB lower. I'm beginning to be a lot less worried about the "you won't set it loud enough" complaints.
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Old 5th February 2012, 06:56 PM   #386
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Quote:
Originally Posted by GM View Post
but it's what it claims to do that concerns me, i.e. provide the information required for someone to determine how much power they need ‘worst case’ if they don't want to clip the amp with whatever digital sources they currently have on hand [or may buy in the future, not to mention some analog recordings] plus I see no way to use it for setting up a proper HT and/or multi-channel music system, so don’t want folks to be mislead into believing this procedure will necessarily do what is being claimed.
the test is intended to provide a figure with one's current system. who claimed and where that it's supposed to give an absolute maximum power level regardless system, room and preference? it's the most power people use in their current homes, with the current speakers. it's a statistic basically.

Quote:
Originally Posted by GM View Post
I mean how does one know how much their existing amp and/or speakers is probably clipping doing this test unless it’s already sufficiently oversized, especially if it’s a tube amp and/or ‘FR’ driver? Or how dynamic the signal?
it's made under the assumption that the amp is not clipping. if one turns the volume all the way up to get to the so called "party level" obviously there's a chance that clipping occurs. obviously, using a scope or sound board to ensure that clipping really doesn't occur would be nice but the test would take too long and get too complicated for most people and they would be put off by it.

Quote:
Originally Posted by GM View Post
Folks tend to set max levels based on audible distortion, so any conclusion seems predicated on a test that may be ill suited for the app since the more dynamic it is, the more it’s likely to be clipped, so it may be just less clipped with the calculated power available unless the normal average is somewhat, to well, below the test setting.
I for one actually measured and I know where my amp starts clipping. the "party level" is well below that point. now if the speakers start clipping is another thing and there's no way to tell unless by ear or with measuring equipment but for the zillionth time: this is not the point. my speakers are rather good and I can listen at very high levels without fatigue so I think it's fair to say that they don't run the into compression too much. maybe that's not the case with everyone, but this being a statistic, averaging applies and hopefully there will be a sufficiently large number of people with good amps and speakers that voted. it's not like the only people with good systems are the one that voted >20V (6.5%). I would find that hard to believe.

Quote:
Originally Posted by GM View Post
Worse, the most dynamic CDs I have don’t have the most power hungry spikes in its loudest passages, so how is some arbitrarily chosen 120 or 220 Hz test tone going to account for these spikes?
again, totally irrelevant. provided that clipping and current limiting doesn't occur, the test frequency is irrelevant. the test frequency is supposed to tell you what's the largest voltage the amp outputs during listening at the maximum listening level. no matter how dynamic the music is, the output voltage would not exceed the measured one. it's not like some music miraculously causes the D/A converter or CD/DVD/SACD player to exceed digital maximum (0 dBfs).

Quote:
Originally Posted by GM View Post
Indeed, the only way I can [or at least once, could] hear them was by noticing more top end ‘air’ around the instruments after seeing the spikes using an SLM, i.e. one step closer to what I’ve experienced in concert halls, piano bars, etc., so how likely is one to notice such subtlety using this test unless their amp, speaker system was already grossly oversized [at least by the tone of this thread] and know what to listen for?
I think it goes without saying that whoever reads this or is interested in it know what to listen for.

Quote:
Originally Posted by GM View Post
105 dB peak/channel at the Lp is a goal for those folks that want to reproduce movie soundtracks at DD/THX/DTS reference. This is based on an 85 dB average at the LP. Since the gain is fixed at 20 dB for the mains and 30 dB for the LFE channel, it’s scaleable to whatever average or peak one desires.
the test is supposed to be made with music. what you're saying is irrelevant. again, why do you keep repeating those 105/85 numbers? AFAIK there isn't any law that forces anyone to listen at 105 dB peak level. "realistic level" is IMO an illusory thing. most people (including myself) would not want/need the SPL of a full scale symphonic orchestra as measured in front row in their living room. for me that doesn't add enjoyment once past a certain threshold and there's no point in torturing the neighbors (not everyone lives in a house) just so I can rest assured that the SPL is realistic.
we can keep hanging on to the space shuttle launch example ad nausea but TBH I'm never interested in reproducing that SPL either. anyone can invent extreme examples like that but it's absolutely pointless.


later edit: I read the last replies only after posting mine.
Pano, 5th, this is getting almost ridiculous. like a previous poster said, this topic is filled with repetitive posts explaining obvious things. and in the end we find that the confusion comes partly from such a basic thing as lack of understanding that a D/A converter can't output levels above a certain level no matter what. what really bothers me is that someone who doesn't understand this basic thing is at the same time so bold in stating that everyone else (including you two) is wrong. I admire your patience but I think it's time to give up.
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Last edited by mr_push_pull; 5th February 2012 at 07:07 PM.
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Old 5th February 2012, 07:02 PM   #387
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Quote:
Originally Posted by 5th element View Post
Pano's test is not about calculating an end SPL figure, nor is it a method of coming up with a way to see if you've got enough amplifier voltage swing given a target SPL figure based on your loudspeakers sensitivity.
Correct, it is a measurement of what is, not what should be. It's meant as a snapshot of voltage levels that people are actually using in their homes. It is not any kind of setup, calibration or target level test. Not at all.

It just so happens that when you measure the voltage at your speakers, you can use Ohm's law to figure out of your amp might be clipping. That's a benefit of actually measuring what's going on.

It is NOT a test to tell you "how little power you need". Some folks have read that into it, but it is not stated in the test. It's just a real voltage test that allows you to know if you are clipping your amp when playing loud.
You could set the volume control anywhere else and the test would be valid - at that volume setting. I just asked folks to turn it up to see what voltages they get when running as hot as they ever do.

That's about it.
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Old 5th February 2012, 07:15 PM   #388
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Quote:
Originally Posted by GM View Post
but it's what it claims to do that concerns me, i.e. provide the information required for someone to determine how much power they need Ďworst caseí if they don't want to clip the amp with whatever digital sources they currently have on hand [or may buy in the future, not to mention some analog recordings] plus I see no way to use it for setting up a proper HT and/or multi-channel music system, so donít want folks to be mislead into believing this procedure will necessarily do what is being claimed.
As mentioned above the fall down is with analogue sources, but it can be used with any number of channels in any situation where there's a digital source and you know what the gain structure/proccessing, is like of the system.

Quote:
Originally Posted by GM View Post
I mean how does one know how much their existing amp and/or speakers is probably clipping doing this test unless itís already sufficiently oversized, especially if itís a tube amp and/or ĎFRí driver? Or how dynamic the signal?
You don't know if it's already clipping when you're running the test. Perhaps it is, but if it is clipping for your given volume setting then the test will identify this and show what size of amplifier you need for it not to clip.

Quote:
Originally Posted by GM View Post
Folks tend to set max levels based on audible distortion, so any conclusion seems predicated on a test that may be ill suited for the app since the more dynamic it is, the more itís likely to be clipped, so it may be just less clipped with the calculated power available unless the normal average is somewhat, to well, below the test setting.
Well Tom said himself that on dynamic music one doesn't hear the flattened peaks as sounding bad as per say and that you need to upgrade to a more capable amplifier to hear what's gone wrong. If the user has used reasonably dynamic material, it is likely that the average levels aren't clipping and that it's only the peaks that are. This test will show this and you will then know, roughly speaking, what size of amplifier you should be looking at.

Also as per the results of the test, I think it shows that most peoples amplifiers are suitable for their listening habits and that most people probably aren't listening as loud as you might expect them to.

Quote:
Originally Posted by GM View Post
Worse, the most dynamic CDs I have donít have the most power hungry spikes in its loudest passages, so how is some arbitrarily chosen 120 or 220 Hz test tone going to account for these spikes?
Well this is dependent entirely on the music and how hard you loudspeakers are to drive. It has already been mentioned that this test isn't focusing on the current the amplifier might have to provide, merely the voltage swing necessary to reproduce the transient without clipping. It is taken for granted that the amplifiers current limiting wont come in.

Quote:
Originally Posted by GM View Post
Indeed, the only way I can [or at least once, could] hear them was by noticing more top end Ďairí around the instruments after seeing the spikes using an SLM, i.e. one step closer to what Iíve experienced in concert halls, piano bars, etc., so how likely is one to notice such subtlety using this test unless their amp, speaker system was already grossly oversized [at least by the tone of this thread] and know what to listen for?
Well indeed, if it's that hard to detect then one could say its largely irrelevant to where someone will set their volume control and it will not have that much, if any baring on the outcome of the test.

Quote:
Originally Posted by GM View Post
105 dB peak/channel at the Lp is a goal for those folks that want to reproduce movie soundtracks at DD/THX/DTS reference. This is based on an 85 dB average at the LP. Since the gain is fixed at 20 dB for the mains and 30 dB for the LFE channel, itís scaleable to whatever average or peak one desires.
I spec'd my system to be able to do this, all the way down to 20hz but the truth is, I never set it that loud as it's painful to listen to (with movies) and certainly not what someone wants to endure for the full length of a movie.


Quote:
Originally Posted by GM View Post
As TD noted:

ďHow much Voltage does it take to reproduce the variety of things I like to listen to in their dynamic entirety?

The answer to me seems that it depends on the dynamic peak to average ratio in the music and the dynamic nonlinearity of the speakers and not just 4X the .5VRms margin.
At no point in this thread has a 4x voltage 'margin' ever been mentioned. Will people please stop mentioning this and read the thread until they understand where this 4x is coming from, it does not represent some preconceived idea about a reasonable average to peak level and has been explained many times over. Specifically post 346.
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Old 5th February 2012, 07:16 PM   #389
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Quote:
Originally Posted by GM View Post
Folks tend to set max levels based on audible distortion
This is an important point that bears further discussion. This is how I see it:
If you turn up the volume until you find it really loud - but your amp is clipping - how do you know you would not have turned it up louder if the amp didn't clip?
You don't. But you might be able to figure it.

If you set your volume, measure the tone and do the math, you might see that your amp is clipping - the maximum voltage your amp can supply is less than 4X the test tone voltage. You might conclude that you could play louder without hurting your ears with an amp that doesn't clip. Myself, I used an amp with so much more voltage than needed that clipping was not a problem.

Of course if the limit is your speakers, or your room, or both - you're out of luck. It's not the amp that limits you, it's speaker or acoustics. At least you'll know your amp isn't clipping.
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Old 5th February 2012, 07:17 PM   #390
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Originally Posted by Pano View Post
Correct, it is a measurement of what is, not what should be. It's meant as a snapshot of voltage levels that people are actually using in their homes. It is not any kind of setup, calibration or target level test. Not at all.
the word is statistic.
if for instance one makes a statistic of average income, it would make sense for me to fill in my current actual income, not the income I wish or my income from 10 years ago. no?
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