SoundStage! Network NRC Measurements for Focus Audio

Jeff Fritz said:

No. Your graph shows linear distortion between the points.

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Well, it does that because those are the only data points I manually extracted from your graph. If you gave me all the data points, my graph would show variations too. Here is your graph:


If you took just the solid vertical axis data points I used, you would also show an exponential drop off from high frequency to low.

Our graph shows, for instance, no measurable distortion at 500Hz.

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Your graph is broken there . You are chopping off everything below 45 db. So I had to guess a value based on trends before that. Again, if you had given me the real data, I would have by definition had the same in my graph. Either that or my math is wrong. If my math is right, then the graph cannot lie.

Your graph smoothes this to the extent that we lose all resolution and the speaker seems to have linear distortion across the frequency band, which clearly isn't the case.

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The smoothing occurs because of the way you presented the data. In your case, your distortion graph does not take into account the fact that the level produced by the speaker is variable. In other words, when the distortion rises, and the speaker level does the same, your graph shows a misleading value because as a percentage, there may not be a rise at all. We can ignore the variable frequency response graph and produce identical graph to yours but earlier you admonished us from doing so.

BTW, I can see why someone would want to see your graph. It accentuates the distortion products and makes it more visible for a speaker designer. For us as consumers though, the type of graph I produced is also useful. For example, if I can use EQ and lower the peaks in FR, and with it, also lower the distortion, then my graph is much more representative than the one you showed.

Again, it could be that I am still not understanding what the numbers on your graph mean. So please go back to my original question. Look at the table I created, and keeping in mind that I had to guess at some values, let me know if the db numbers are right.

Thanks,

Jeff Fritz said:

Ultimately, I think where we are at is that some of you would like to see distortion as a percentage on a graph. I respect that. But what we are doing is more enlightening, IMO, and is an industry standard for these types of measurements. Our graphs are not produced by us, but by third-party engineers at the NRC that have been measuring loudspeakers for many years. No politics are involved.

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Surely. But this point also opens the door to those we argue about the value of publishing raw measurements in consumer reviews. 95% (I just put this value to show a high percentage) of readers do not know what a dB really is, and the associated maths are beyond there interests - they just interpret the graphs by comparison with known references. The percentage would have some meaning to them - perhaps not easy to associate with sound quality.

One question can arise. The measurements in your amplifier and preamplifier sections are fully commented with great detail, explaining the most interesting technical features shown by the measurements - I appreciate them a lot. Why are the speaker measurement pages non- commented? Perhaps writing a FAQ to this section could be of great help.

Please take this comment as a positive suggestion - I really consider the measurements useful - it is always the first part I read in a review, when they exist. But I think there is still a long way between them and real useful information for the other 95% of people.

das said:

4) Finally, if you want to compare and see "good" and "bad" measurements, spend some time at www.speakermeasurements.com

Thanks,

Doug Schneider
www.SoundStageNetwork.com

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Doug,

Thanks for the reference (pun intentional)!

amirm said:

If my math is right, then the graph cannot lie.

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Say amir,

This reminds me of the aphorism, "There are LIES...DAMN LIES...then, there are S T A T I S T I C S!" Hehe...you know what I mean

c1ferrari said:

Say amir,

This reminds me of the aphorism, "There are LIES...DAMN LIES...then, there are S T A T I S T I C S!" Hehe...you know what I mean

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There are many variations of that. When I used to do a lot of computer performance optimizations, there was the line that "there are lies, damn lies and benchmarks!"

amirm said:

There are many variations of that. When I used to do a lot of computer performance optimizations, there was the line that "there are lies, damn lies and benchmarks!"

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Exactly!

FrantzM said:

I also did find these papers very interesting .. We don't seem to perceive distortion (at least the way it is usually measured) very well... High level of THD sems perfectly totlerable ...

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Agreed, please give me a graph that shows the THD, even though I can't hear it