Silver RCA Cable-share your experience, opinions here!

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#522
mmerrill99, thank you for the link. ( The quote is from that text)
In case in Fig.4, the characteristic impedance is 73 Ω at the sending end and over 80 Ω at the receiving end of the cable. In other words, the characteristic impedance measured with TDR increases toward the receiving end.
However, we obtain the same results when we connect the sending and receiving ends in reverse. Therefore, the characteristic impedance of the cable should be the same at the sending and receiving ends.
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Now, if you want you may reply to my two questions

George
 
#524
Honestly guys, look up the Gish Gallop: we have several members here that are tying up many of you with preponderous levels of BS that require careful rebuttal. Guess which takes longer to explain? Ignore list the trolls and they have little to feed on.
 
#526
If when you measure something you get a daft answer (like a cable which exhibits the same directionality which ever way round it is) then one of the following is probably true:
1. your equipment is faulty
2. your understanding is faulty
3. you are not measuring what you think you are measuring

In the case of the magic 73/80 ohms cable the most likely explanation is some sort of reactive loading at one end of whatever is attached to the cable. I don't think we should throw away Maxwell and Heaviside just because someone has done a poor measurement.

In any case, this has absolutely nothing whatsoever to do with analogue audio interconnects.
 
#529
scott wurcer said:
Interesting to note very high quality cable and connectors (gold plated SMA for instance) are far cheaper than many of these audiophile concoctions (sometimes FAR cheaper). Do they show up much, no story but real engineering I guess.

May I suggest a new tweak, c-clamps applied at carefully computed points along a cable to modify the impedance. Better yet Jorgensen clamps made of myrtle.
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The was a loopy integrated amplifier designed I suspect for the japanese ultra-fi market in the late 80s that used semi-rigid and SMA. I did seriously consider doing my whole system in SMA but at the time the cost of the tooling required put me off. These days premade cables are cheap enough I might get tempted again 🙂.
 
#531
Galu said:
<snip>

When discussing AC signals, the concept of 'return current path' must be a convenience, considering that the electrons simply oscillate in the cable.
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We are using models, what the electrons (and holes sometimes) do is most probably something completely different.

So, whenever we think about current we should think in loops.

Instead of several 'return pathways' would it be appropriate to consider there to be several 'signal transfer loops', which vary in impedance?

Either way, how does the existence of pathways or loops of different impedance affect the accuracy of signal transfer?
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The loops are not only differing in impedance but in loop area as well. Although it is all "lumped" together (inductance of the loop, hence impedance, is dependent on the loop area) it helps to seperate it in thoughts when thinking about he different interference mechanism.
Loop area is important to if you think about receiving interfering magnetic fields.

If we had no impedance it would often don´t matter but common impedance is the reason for coupling.
It depends on many variables, on the gain that is available, if E fields or H fields are the main source of interference, the frequency range of the interfering fields and so on.

And of course the internal construction details of the devices play an important role.

Frequency dependent phase alterations or signal induced back EMFs in the signal/ground loops? I need expert help! 😕
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Without analysis of the specific situation you´ll never know.....
 
#532
scott wurcer said:
George you can't ignore the cable loss in the TDR if it is easily visible, you need the full telegrapher's equation.

EDIT - Dave's No 2 above
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Thanks Scott.
It is "a series of impedance changes throughout the cable length" that Mmerrill99 writes that change when cable is reversed.
This is ONLY what I am asking him to confirm: Whether he has tested it himself using time-domain reflectometry (TDR). A yes or no will suffice. I am not about to ask any follow up question.

Of course Mmerrill99 may respond that he obtained his experience (if it is his own experience) by other means than TDR. In that case, he might be kind enough to name the test method.

George
 
#534
Yes, an asymmetric arrangement may have asymmetric properties.

The usual claim is that a cable which is symmetric in construction, apart from the direction the copper was drawn from the die (or something similar), shows asymmetry in passing audio signals. As far as I know there is no evidence (beyond anecdote) that this effect is real, and no plausible explanation, so therefore no reason to accept it.
 
#536
Jakob2 said:
We are using models, what the electrons (and holes sometimes) do is most probably something completely different.
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Thanks for your reply. Physics provides models, each of which is used to explain a particular physical phenomenon or behaviour. Models are tweaked or replaced as new behaviours are discovered that do not fit in with the current models. An electron, for example, can be described by a particle model, a wave model or a wave/particle duality model, depending on which behaviour you seek to explain.

Physics is not set in stone, it is constantly evolving. However, I do not offer this as justification to those who think a silver RCA cable sounds better than a copper one! 😉
 
#537
gpapag said:
Thanks Scott.
It is "a series of impedance changes throughout the cable length" that Mmerrill99 writes that change when cable is reversed.
This is ONLY what I am asking him to confirm: Whether he has tested it himself using time-domain reflectometry (TDR). A yes or no will suffice. I am not about to ask any follow up question.

Of course Mmerrill99 may respond that he obtained his experience (if it is his own experience) by other means than TDR. In that case, he might be kind enough to name the test method.

George
Click to expand...

Sorry if my explanation is not up to snuff but Jocko Homo has measured directionality differences in SPDIF cables here

And his post here summarises "Digital cables are directional. Only thing I can come up with is there are minute differences in rho (reflection coefficient) that don't mean diddle on my TDR, but can slightly affect dispersion, and that sort of crap, which can, in turn, affect the recovered clock signal."
 
#539
DF96 said:
The usual claim is that a cable which is symmetric in construction, apart from the direction the copper was drawn from the die (or something similar), shows asymmetry in passing audio signals. As far as I know there is no evidence (beyond anecdote) that this effect is real, and no plausible explanation, so therefore no reason to accept it.
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Ok, in my anecdotal/subjective experiences swapping interconnect direction one channel can shift image sideways and with associated loss/change of focus (L/R and depth) and the lower the operating level on the cable the more evident the effect...ie phono vs line.
It seems as though system excess noise is affected/triggered differently consequent to the cable direction......somehow.
Inverse in coherence of noise of L/R channels might account for the subjective observations.
The better the system, ie the lower the system intrinsic noise and the lower the system excess noise the less the subjective effects.
Someday I will work out how to measure what I hear with cables, same with a bunch of other stuff.


Dan.
 
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