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Old 28th October 2011, 04:44 PM   #17051
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Quote:
Originally Posted by simon7000 View Post
Or am I giving values for the lazy?
Ed you would appriciate this. I like to put RCA to BNC adaptors on cheap video cables (you know the "yellow ones" that come with every DVD player) to avoid giving more money to Pomona. Yesterday I spent over an hour tracking down a grounding problem only to find that the shield on one had opened up.
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Old 28th October 2011, 06:27 PM   #17052
jcx is offline jcx  United States
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Or am I giving values for the lazy?
no - its a reading comprehension problem on your end

given an LCR filter example with a fc near 3 KHz an engineer would say "yeh thats audible"

which is what my posts, ref said


but it doesn't help with the argument of whether speaker cable of the same C from an amp with less than 4 uH output Z shows any audible frequency rolloff from cable C

or indeed if the dielectric properties were varied from air to those of PVC at a kHz rate as a thought experiment - would there be a audible signal change at the (typical ~90 dB SPL re 1W) loudspeaker? - above the human audibility threshold in a anechoic chamber after minutes of accommodation

which is the type of argument I would use for many cable claims – overbound the variation in a cable property claimed to be important, see if it could result in a change in a simplified circuit model of its application, is the difference even expected to be audible in the absence of signal at all above the electronic or our hearing noise floors

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Old 28th October 2011, 06:45 PM   #17053
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We could discuss your grammatical constructions with close repetition and general style.

Or we could progress to Bear's observation that different metals with the same L & C sound different. They also measure different amounts of resistance and extremely small differences in IM distortion. Is there any other measurable difference?

I read into Bear's discourse that he used the same connectors, so is that truly out of the issue?


Scott,

If you had bought $1000 video cables you wouldn't have those issues! (I find that I can get BNC cables for about the same price as RCAs!)

Just down the road is a stadium where the pseudo IT guys installed a video to ethernet system using BNC to F then F to RCA for all of the connections, just waiting to see how long till it all goes dead.

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Old 28th October 2011, 06:53 PM   #17054
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Originally Posted by simon7000 View Post
Or we could progress to Bear's observation that different metals with the same L & C sound different.
Unfortunately, he admits that he doesn't have any data to support this (he's an honest guy, which I appreciate). No-one else does, either.
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Old 28th October 2011, 07:19 PM   #17055
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Unfortunately, he admits that he doesn't have any data to support this (he's an honest guy, which I appreciate). No-one else does, either.
In my OPINION there are very small measurable differences. Although at those levels I find it difficult to believe the resistance or distortion differences can be heard. So although the possibility exists that may be what is being perceived there is always the remote chance there is something we are failing to measure.

In my OPINION there can be significant differences in cable insulation having an effect on some systems. As this can add not just capacitance but as Scott has demonstrated dielectric absorption shows up as an increase in noise. I am also of the OPINION that out of band noise can still degrade the reproduction system. So it is not as wild a claim that improved insulation makes a real perceived difference even without going to the extremes of deliberately high capacitance cables.

I don't think there is much debate that connectors can cause problems, only to the extent at which those issues reach levels that can be heard.

Now if you allow the premise that some humans (I know a presumption on my part) can perceive distortions of -140 db to -160 db re the peak sound pressure level, then many of these issues would actually have a basis!

But if I were to bet on it, I would wager that the multiple FFT averages allow looking at conventional issues yet missing something that averages out that our hearing mechanism picks up.

At the recent AES I spoke to a few of the instrument manufacturers about doing some different tests and other than they thought the idea interesting they had no suggestions as to how to go about it!

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Old 28th October 2011, 07:35 PM   #17056
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Problem is, you only get as high as -140dB in the presence of signal at 0 dB. Oooops. The DA noise is a red herring for this application.

So far, no-one has been able to demonstrate audibility of different metals. And that's in accord with the predictions of dull, stodgy, reliable, conventional engineering. Ah well, that frees up people to work on stuff that actually matters.
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Old 28th October 2011, 07:54 PM   #17057
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Problem is, you only get as high as -140dB in the presence of signal at 0 dB. Oooops. The DA noise is a red herring for this application.

So far, no-one has been able to demonstrate audibility of different metals. And that's in accord with the predictions of dull, stodgy, reliable, conventional engineering. Ah well, that frees up people to work on stuff that actually matters.
SY

Some of us aren't using recordings! But even with a 24 bit recording (As far as I know there aren't any really there yet) that would allow you more than 140 db of resolution. Noise isn't quite the same issue. If you understand the ears ability to narrow the observed bandwidth (You know that critical band stuff) that allows analysis at another 30 db or more below the broadband noise level. So although it is unlikely there can be a basis for -170 db perceptions! Now has anyone ever demonstrated this ability in a well controlled test? Duh not that I know of. But if I can measure components and reduce the distortion to -160 or -170 db levels without significant cost increases then it would be silly not to.

That is why I talked to manufacturers at the AES show about no cost methods (or even ones that lower costs) to improve their products.

I would find it hard to believe you would argue that an improvement in part quality with no increase or even a decrease in price is a bad thing!

But it was interesting at the AES to find the tweak designers I know, all use resistors that measure very well. The depth of knowledge about part performance that was reported to have been tested by ear and agreed with measured results was most interesting.
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Old 28th October 2011, 08:00 PM   #17058
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When you can find anyone who can hear the Sousa band in Bill Waslo's clever demonstration (I think that's only at -65dB?), get back to me about that -170dB stuff.
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Old 28th October 2011, 08:13 PM   #17059
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When you can find anyone who can hear the Sousa band in Bill Waslo's clever demonstration (I think that's only at -65dB?), get back to me about that -170dB stuff.
Do you really want to argue 65 db dynamic range is all you need?

Well when I posted ninth harmonic distortion at -60 db only a few couldn't hear that. We could try 9th at -80 db, that shows up on our in house listening test for some folks. So the issue most likely is what are you listening for?

That just illustrates we really don't know exactly what is going on.

I just came back from an arena. There is a light buzz coming out of three of the loudspeakers. They are on a 70 volt speaker line. One wire going to them has shorted to the conduit. I measured 10.5 millivolts across the loudspeakers as a result. That is 76 db down. I still have to fix it cause it can be heard quite clearly even in an arena!
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Old 28th October 2011, 08:17 PM   #17060
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Do you really want to argue 65 db dynamic range is all you need?
Cute, Ed, but I didn't argue that. You do, of course, understand the difference between a signal that's 65dB down from full scale and a signal that's 65dB down in the presence of a full-scale signal.
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