Perhaps I misunderstoodMarkw4 said:
?traderbam said:
I agree that there may be small effects explainable by science which thus far have not been explained simply because nobody has thought hard enough - although in many cases this is because the lack of real experimental evidence serves as lack of motivation for hard thought. However, there always seems to be an undercurrent of 'science cannot explain this' (i.e. we need new science to explain audio) which is quite different from 'science can explain this even though thus far it has not'. In most cases the 'science cannot explain' people are ignorant of science so are not in a position to make such a statement. It would be like people who have never heard of Rayleigh scattering (and Maxwell's equations) saying that science cannot explain why the sky is blue.
The bolded text I believe to be the position of most informed people & it is the desire of many to try to encourage the work necessary to try to think hard about what might become "explainable by science which thus far have not been explained simply because nobody has thought hard enough"
I don't know about the current cable direction debate in this thread but I do have a problem with people generally using "blind testing" (usually ABX specified ) as the yardstick by which to consider whether an observation is "worthy" of investigation. I've said it before & will continue to say it, ABX testing, as practiced on forums, is just as error prone as sighted listening, perhaps more so but in the opposite direction.
You could be right. On the other hand, we should be careful not to accidentally argue a valid observation into the long grass just because it contravenes our sense of order or makes us feel superior. We engineering/science types are very good at arguing.
Try end for ending an unbalanced coaxial guitar/bass cable, while you are at it try a few other such guitar cables with similar/blameless LCR values but differing dielectric and differing sheath insulation materials, usually polymeric and of diverse range including extenders/additives/pigments.
Repeat the above for decent quality/blameless and seemingly similar RCA terminated Interconnects.
Modern off the shelf cables are typically same/consistently/perfectly prepared and terminated and at least some will cause systems to reproduce sound subtly differently, and further direction of such interconnect cables will further cause the system to reproduce sound subtly differently.
If you were to earnestly and properly trial the above described experiments and you noted any subtle differences your deeper interest ought to be piqued........however you must trust your ears in addition to your current and seemingly exclusive trust in the (simplified) equations.....dichotomies and questioning will inevitably result in such case.
Ears require rigorous training before trusting, it can be that uber multiple sighted AB and/or uber multiple unsighted with feedback AB comparisons are required to establish and consequently reinforce this self trust.
The next step is to search is for confounders in the case of such cables that are soldered/connected correctly and connectors that seemingly provide consistent/reliable low level contact resistance/reactance.
If the above electrical conditions are satisfied and still a subjective difference is noted, what then ?.
Dichotomies generate lists of questions and subsequent strategies of measurement protocols planned to objectify and categorise observed system fine behaviours.
This is key to progress in audio recording, processing, storage, transmission and final reproduction.
Dan.
Last edited:
Sure. If we knew how to measure sound quality then we would not need human observers. Given that we do not know how to measure sound quality then genuine human observations are precious indeed. So finding that motivation is crucial.
It also helps if you are crazy obsessive about audio, like me.
There's also the colloquialism/aphorism in the US: "When you hear hoofbeats, think of horses not zebras".
Zebra (medicine - Wikipedia)
The SNR of anything impressions wise in audio is so terrible that it's hard to do anything actionable with it. So going down the list of possible alternate effects that are much more likely and eliminating them is, as always, the best way forward.
Ed's graphs are usually rather interesting, but then his explanations that wanders off to the nether land confuses people like me. We may discover something with similar and improved experiments, but it is not easy to find funding to understand an effect so subtle while other areas still show higher potential of improvement.
Hi.
Yeah, I ran experiments of two channel mono signal of varying types (tones/noises/music) fed from USB DAC into 'typical' mid-fi integrated stereo amplifier box (system) and derived channel difference signal according to system throughput channel imbalance, IOW foundation residual/difference was observed as is expected and was recorded.
Reversing the direction of one channel interconnect changed the nature of this difference signal and this (different) difference signal was also recorded.
Comparing these two first order difference signals derives a second order difference signal.
I need to do calibration runs, but guesstimate (using DAW digital gains) is that these differences are not more than 80dB or so down wrt originating signal for this kind of typical/representative domestic 'decentish 'gear.
Dan.
Last edited:
But it's not an EM field with the switch open; it's only an "E" field.
Last edited:
Closing the switch completes the circuit and is exactly equivalent to a Heaviside step function applied to the loop. Loop-antenna theory applies to this problem and I'm sure the exact solution has been done somewhere. As you see here the 1 meter loop is resonant at 300MHz and at f << resonance the loop acts like an inductor. Get a two channel current probe and a reed relay and do the experiment, you will find the current at both ends of the battery starts instantaneously and with care and the right equipment this can be done to the 10's of nsec level.
Loop Antennas
Last edited:
One plausible explanation is that cables NASA use are satisfactorily usable in both directions. Moreover, I suspect that no more funding will be made available even if there is slightly better signal resolution due to cable direction.
Cable material and directionality are interesting subjects, but not interesting enough for me to justify spending large sum of time or money on. Knowledge of the true nature of the properties helps me enjoy better entertainment and avoid snake oil products. However, others may feel differently.
MIL-W-22759 specification
To the best of my knowledge (till some 10 years ago), cable directionality was not an enlisted part of any space/aviation requirement/specification
https://nepp.nasa.gov/DocUploadsSpecs/S-311-P-13B.pdf
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940024194.pdf
http://www.standard-wire.com/downloads/swc_catalog.pdf
https://www.is-rayfast.com/wp/wp-content/uploads/2017/03/Airframe-Wire-Cable-Guide-2016-1.pdf
Electrical connectors is another (expensive) topic)
https://nepp.nasa.gov/DocUploads/E9217401-8544-4DD6-B67488D4410E9762/conn.pdf
George
Only that verification of conformance to some NASA/MIL/Aero/BMS/SAE/EN….. specs costs a lot of money .
To the best of my knowledge (till some 10 years ago), cable directionality was not an enlisted part of any space/aviation requirement/specification
https://nepp.nasa.gov/DocUploadsSpecs/S-311-P-13B.pdf
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940024194.pdf
http://www.standard-wire.com/downloads/swc_catalog.pdf
https://www.is-rayfast.com/wp/wp-content/uploads/2017/03/Airframe-Wire-Cable-Guide-2016-1.pdf
Electrical connectors is another (expensive) topic)
https://nepp.nasa.gov/DocUploads/E9217401-8544-4DD6-B67488D4410E9762/conn.pdf
George
Attachments
With these sorts of claims it's incredibly rare to get the full experimental information. Even if I wanted to I can't try and reproduce Ed's experiment, as he's given nowhere near enough info....
Evidence?Max Headroom said:
Subtle differences are far more likely to be going on in my head than going on in the direction of the wires. Which allegedly simplified equations do you have in mind?
You repeated this measurements several times to eliminate contact resistance, cable placement, intermittent interference etc. so that cable direction is the only thing which correlates with the difference signal? You have posted the data somewhere for others to look at it?
A plausible explanation is that all non-faulty symmetric cables are usable in both directions, but I guess this is not what you meant.indra1 said:
Another less plausible explanation would be that there is a secret group in NASA which tests all system-critical cables for directionality. The group has to be secret because there is no explicit funding for it, so it has to 'steal' budget from other groups.
Or maybe someone just dowses each cable and pronounces which way it should be connected?
I tend to agree with many of your points Scott. Clearly it is easier to satisfy requirements from NASA compared to audio. NASA posses clear quantified specification while audio serves subjective entertainment experience with many of the subjective stimuli remain non quantified due to various reasons.
Close enough to what I meant, symmetric cables implies meeting specification when used in any direction and corresponding screening procedure ensure that despite variations, delivered cables meet specification upon usage. It is obvious that current technology delivers usable symmetric cables, but I am not yet informed that current technology can deliver symmetric cables so perfect with no directional asymmetry deviation whatsoever measured by any means.
Perhaps managed under MIB with inter galactic funding?
A cable which is symmetric or a tiny fraction of a wavelength in length, and contains no exotic materials cannot be directional. There is nothing to sense the direction of a signal, and nothing to do anything with that information even if it had been obtained.
For a really short cable (and almost all analogue audio interconnects are really short, in wavelength terms) even some asymmetry will not make the cable noticeably directional. If it could be shown that a particular cable really is directional then the first place to look is asymmetric faults, such as solder joint and mating surface resistance differences or shielding quality.
For a really short cable (and almost all analogue audio interconnects are really short, in wavelength terms) even some asymmetry will not make the cable noticeably directional. If it could be shown that a particular cable really is directional then the first place to look is asymmetric faults, such as solder joint and mating surface resistance differences or shielding quality.
- Status
- Not open for further replies.