The cable conundrum

ack said:

I can't quantify these phase angles (they are not my theory, this is basic electronics), but the patents do make specific claims based on mathematical formulas, and they are huge; see http://www.freepatentsonline.com/5956410.pdf which claims that: "[for a cable with total distributed capacitance of 90pF] using the impedance meter it was shown that at a frequency of 80Hz the impedance phase angle was found to be -85.46 degrees, and at a frequency of 431Hz the phase angle was found to be -87.37 degrees". He then mathematically calculates power losses at 80Hz as being 7.92% and at 431Hz 4.41% - if true, these are significant losses; read the whole patent if you have more technical questions. Of special interest to me here is that total capacitance of 90pF in that cable under test... why? because this is very low as is, and if you look at the specs of very pricey cables, like Nordost's Odin, which measure about 9pF/foot or 90pF for a 10ft run, then one begins to wonder: do expensive cables also really suffer from such extreme phase issues??? That's HUGE, if true. MIT basically claim that there is exactly one frequency where the power transfer is optimal, and everywhere else there are losses, small or large: "The parallel capacitance of the cable is predisposed to store a greater magnitude of electrical energy than at other frequencies. Furthermore, the series distributed inductance of the cable is also predisposed to store a greater magnitude of electrical energy at certain frequencies than others."

These claims then lead to those MIT articulation-pole designs and another patent http://www.freepatentsonline.com/6658119.pdf which explains those designs (btw, it was claimed by others recently that this patent is now in the public domain), and wherein it is also claimed that the networks are chosen such that their phase angle is around -45 degrees at the chosen frequency, to compensate for the cable's positive phase angle deviation at the same frequency. The end goal, they claim, is to produce a "more uniform audio output". On the other hand, they also do admit that "in other embodiments the network can be designed to emphasize certain frequencies".

Peter

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microstrip said:

The claims are not huge - they are minimal. The phase angles you referring are capacitor phase angles of a low capacitance value unloaded cable - not the phase of audio signals! And if you compare the amount of difference of the energy stored in the cable (few nJ) with the total signal energy involved in the quoted 50V excitation delivered to a typical 4-8 ohm speaker you will conclude that you are in the -120 to -130dB zone - something we already know. The big question is still "Do these minimal electrical differences affect sound quality?"

The main objective of the patent is not to make science - it is to prevent others to use this technique in cable manufacturing.

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microstrip said:

FYI F. Toole finds that the differences between proper designed cables have minimal effect on sound.

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amirm said:

That's what I was talking about: measuring the output of the system at speaker terminals. If the difference is big then it should show up there and whether the factor is common mode or not at the interconnect would not matter.

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DaveyF said:

Tim, while I like listening on my headphone system on occasion, it really isn't of the same level of reproduction as I can get on my system. For one, the ability of the headphone system is far inferior when it comes to recreating the overall 'gestalt' ( here I use this term again, as it really does sum up the feeling) of being at the 'live' venue. My headphone system is based around Senn 600's with Cardas cabling. ( which BTW was an audible improvement over the stock cable) and was heard by all when my audio group did an AB' with the same phones with the stock cable.t that wasn't
I know YMMV.

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ack said:

Hmm, did I say they are phase angle of _audio signals_? I don't think I did; I said "LC, in fact, are solely responsible for phase issues introduced (to various degrees) by cables" - we are talking about voltage/current phase relations here (of capacitive nature as you point out, due to the negative angle), and based on that I surmised that perhaps these issues are more evident where there is plenty of voltage and current, i.e. speaker cables...

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DaveyF said:

Tim, I think a systems ability to resolve what's on the recording has to do with the "weakest link in the chain" theory. From the source to the speakers everything has to be optimized to get the maximum resolution off the software.
That includes the room and the noise floor in the listening area. IME, cabling contributes greatly to the experience, along with everything else in the system.

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microstrip said:

The claims are not huge - they are minimal. The phase angles you referring are capacitor phase angles of a low capacitance value unloaded cable - not the phase of audio signals! And if you compare the amount of difference of the energy stored in the cable (few nJ) with the total signal energy involved in the quoted 50V excitation delivered to a typical 4-8 ohm speaker you will conclude that you are in the -120 to -130dB zone - something we already know. The big question is still "Do these minimal electrical differences affect sound quality?"

The main objective of the patent is not to make science - it is to prevent others to use this technique in cable manufacturing.

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opus111 said:

Why don't you start a whole new thread on that topic? Could be interesting...

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microstrip said:

Sorry to insist, but the current is also our divergence. The phase angles that are reported were measured with almost null current, as there was no load (unterminated, as said in the text) . And you are using as an argument that there is plenty of current!

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microstrip said:

The more I read the patent the more I get the feeling that sometimes they are comparing oranges with apples to fill the text - for example when they refer to the relative differences in energy storage, and compare them with component tolerance. For me it has no meaning at all.

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