$79,000 Raidho D-3 speakers make popping sound when SPL reaches 95 dB at 1 meter? - Page 2 - AVS Forum
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post #31 of 41 Old 03-16-2014, 07:14 AM
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That can't be a real thread, it reads like a South Park episode where Cartman inherits a massive trust fund. biggrin.gif
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post #32 of 41 Old 03-16-2014, 11:42 AM
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Quote:
Originally Posted by amirm View Post

Thanks for the link. It was a good read. But Arny said the founder had sit through DBTs but that report says they didn't even conduct the test. The timing though matches what Arny said. So I wonder if Arny's recollection is faulty in this regard.

By the way, I have Transparent Audio cables that were mentioned in the link. They have a network in them which can filter high frequencies. This is a measurement showing that using my Audio Precision Analyzer in loop back mode (input and output of the same instrument). I set the output impedance to 600 ohms and got this (in yellow):

That is likely not audible but if one had a pre-amp with even higher output impedance, it might be. In that sense, it was a good thing Tom didn't get to set up his test smile.gif.
Well, yes, that 0.1 db loss at 20kHz is well below 20kHz JND which is at least 3 dB from other literature and is around 1 dB at 16kHz. So, then the question will be at what pre-output impedance gives you at least 1 dB at 16kHz with those cables. You also need to be able to detect 16 kHz in the first place. wink.gif
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post #33 of 41 Old 03-16-2014, 11:45 AM
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Originally Posted by arnyk View Post

Tom has had similar experiences with other high end audio component manufacturers.

I am sure he did wink.gifbiggrin.gif he's been around the block a few times. biggrin.gif
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post #34 of 41 Old 03-16-2014, 07:25 PM
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Quote:
Originally Posted by CharlesJ View Post

Well, yes, that 0.1 db loss at 20kHz is well below 20kHz JND which is at least 3 dB from other literature and is around 1 dB at 16kHz.
Oh, do tell; what literature? smile.gif
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So, then the question will be at what pre-output impedance gives you at least 1 dB at 16kHz with those cables. You also need to be able to detect 16 kHz in the first place. wink.gif
Remember, JNDs are average metrics. They do not claim to cover all individuals. I can't hear 20 Khz and I suspect no one in my age bracket does either. But I know my son does. Averaging my score and my son's would indicate that my son can't hear 20 Khz as well and that would be wrong. Not saying the data is useless but you have to allow for an individual being the exception. Further, loudness level testing is very difficult. Typical data is accompanied by pages of explanation of how the test was done. I don't recall ever seeing a single figure metrics as you state.

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post #35 of 41 Old 03-17-2014, 11:11 AM
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Quote:
Originally Posted by amirm View Post

Oh, do tell; what literature? smile.gif
Remember, JNDs are average metrics. They do not claim to cover all individuals. I can't hear 20 Khz and I suspect no one in my age bracket does either. But I know my son does. Averaging my score and my son's would indicate that my son can't hear 20 Khz as well and that would be wrong. Not saying the data is useless but you have to allow for an individual being the exception. Further, loudness level testing is very difficult. Typical data is accompanied by pages of explanation of how the test was done. I don't recall ever seeing a single figure metrics as you state.
Florentine, Mary, et al 'Level Discrimination as a Function of Level for Tones from .25 to 16kHz. Journal of Acoustic Society of America, 81(5) May 1987, pg 1528-1541.

Villchur, Edgar, 'Speaker Cables, Measurements vs Psychoacoustic Data,' Audio, Jul 94, pg 34-37.

While your son may hear 20kHz, I bet his JND is nowhere near 0.1 dB and most likely closer to that 3 dB data.
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post #36 of 41 Old 03-17-2014, 11:29 AM - Thread Starter
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It would be helpful if Amir could provide the length of the cable he measured.

Edit: That plot looks to be about 0.14 dB down at 20 kHz. That implies a -3 dB frequency of about 100.5 kHz, which for a 600 Ohm source implies 2400 pF of cable capacitance. Typical 75 Ohm coax is around 20 pF per foot, so a normal 75 Ohm coax would have to be 120 ft. long to give such data. Amir did mention that there was some kind of network on this cable though.
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post #37 of 41 Old 03-17-2014, 05:12 PM
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Originally Posted by andyc56 View Post

It would be helpful if Amir could provide the length of the cable he measured.

... Amir did mention that there was some kind of network on this cable though.

Yes, but I believe the patent is for rf noise, etc. nothing to do with the audio band alteration.
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post #38 of 41 Old 03-17-2014, 06:10 PM
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Quote:
Originally Posted by CharlesJ View Post

Florentine, Mary, et al 'Level Discrimination as a Function of Level for Tones from .25 to 16kHz. Journal of Acoustic Society of America, 81(5) May 1987, pg 1528-1541.
I have the paper and read it a while ago. Don't recall any reference to 20 Khz in there. As you can tell from the title of the paper, it only goes to 16 Khz. Can you please quote the relevant section that says 3 db delta L for 20 Khz?
Quote:
Villchur, Edgar, 'Speaker Cables, Measurements vs Psychoacoustic Data,' Audio, Jul 94, pg 34-37.
As far as I recall from snippets I have seen from this article, he got his data from Mary Florentine's article above. Do you have the full article and if so, can you please post the original snippets to see if it is otherwise?
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While your son may hear 20kHz, I bet his JND is nowhere near 0.1 dB and most likely closer to that 3 dB data.
No case was being made for 0.1 db being audible. I said that if your preamp has higher impedance than 600 that I tested, that might be the case. Indeed there are tube pre-amps that have higher output impedance. In addition, I tested a very short 1 meter interconnect. Longer cable would have higher capacitance and help with the roll off.

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post #39 of 41 Old 03-17-2014, 06:12 PM
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Quote:
Originally Posted by andyc56 View Post

It would be helpful if Amir could provide the length of the cable he measured.

Edit: That plot looks to be about 0.14 dB down at 20 kHz. That implies a -3 dB frequency of about 100.5 kHz, which for a 600 Ohm source implies 2400 pF of cable capacitance. Typical 75 Ohm coax is around 20 pF per foot, so a normal 75 Ohm coax would have to be 120 ft. long to give such data. Amir did mention that there was some kind of network on this cable though.
As I just noted, I tested a 3.3 foot/1 meter interconnect. Note that the other graph was for a standard coax interconnect and this one clearly has a sharper roll off. I have not tried to open it to see what is in it.

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post #40 of 41 Old 03-18-2014, 02:50 PM
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Quote:
Originally Posted by amirm View Post

I have the paper and read it a while ago. Don't recall any reference to 20 Khz in there. As you can tell from the title of the paper, it only goes to 16 Khz. Can you please quote the relevant section that says 3 db delta L for 20 Khz?

Well, don't have to since Villchur's paper referenced the Florentine paper and Viemeister, N.E. "Audio Intensity Discrimination at High Frequency in the Presence of Noise" Science, vol 221, pp12-6-1208(1983).
And, it seems that I made a small mistake where that 3 dB happens. Villchure explains the Florentine paper and states that at 10 kHz the average was 2.12 dB, minimum was 0.47 dB; 16 kHz the average JND was 3.05 dB and the smallest was 1.31 dB.
So, that 3 dB is at 16 kHz not at 20 kHz.

Since the JND was increasing upwards from the most sensitive region between 1 kHz and 4 kHz one can clearly see that at 20 kHz it will be a lot more than 3 dB.
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No case was being made for 0.1 db being audible.
Of course not.
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I said that if your preamp has higher impedance than 600 that I tested, that might be the case. Indeed there are tube pre-amps that have higher output impedance. In addition, I tested a very short 1 meter interconnect. Longer cable would have higher capacitance and help with the roll off.
Yes indeed the case. And a passive pre can further lower the roll off point even down from 2 kHz.
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post #41 of 41 Old 03-18-2014, 03:58 PM
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Quote:
Originally Posted by CharlesJ View Post

Well, don't have to since Villchur's paper referenced the Florentine paper and Viemeister, N.E. "Audio Intensity Discrimination at High Frequency in the Presence of Noise" Science, vol 221, pp12-6-1208(1983).
I was also asking if you had the Florentine paper. If you read that, you see that is hard to draw strict conclusions from it. This is an example:

"Not only do our listeners differ in overall sensitivity, but the effect of level and the interaction of level and frequency differ across listeners. However, the main effect of frequency is generally the same for all listeners as shown by the nonsignificant interaction of frequency and listener. "

As you see, it clearly states that individuals vary with respect to their level sensitivity. What they say is similar is what happens in a relative manner from one frequency to the other. And even that has some non-monotonicity that they can't explain.
Quote:
And, it seems that I made a small mistake where that 3 dB happens. Villchure explains the Florentine paper and states that at 10 kHz the average was 2.12 dB, minimum was 0.47 dB; 16 kHz the average JND was 3.05 dB and the smallest was 1.31 dB.
So, that 3 dB is at 16 kHz not at 20 kHz.
I am glad we agree it didn't include 20 Khz. smile.gif On the other numbers, again, Villchure has no data of his own. It all comes from Florentine paper. And there, there is a breakdown of everyone's result. We see that the listener "RP" achieved a level difference of 1.03 db and that was the mean for all the trials. So some were even smaller than 1 db. Once one averages all the listeners you get the numbers you list. We can't bank on that being everyone's threshold.
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Since the JND was increasing upwards from the most sensitive region between 1 kHz and 4 kHz one can clearly see that at 20 kHz it will be a lot more than 3 dB.
I don't know. Many people can't hear 20 Khz. Once we find people who readily hear it, they may have have sensitivities that are lower. After all, only 6 listeners were used in Florentine's study. That is too small of a sample size to determine the floor at 16 Khz let alone interpolate to 20 Khz.

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