GeorgeBynum
Active Member
It's OBVIOUS ... lack of money in the sellers hands/pockets.<BIG grin>
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[Request] Shielded Power Cable
- Thread starter woodyohill
- Start date
I don't disagree, but I would like it if people who advocate the benefit to shielded power cables would provide a more precise explanation of the problem that supposedly is correctable by shielding the cable. It is usually the case with this kind of thing that all you get is a scattering/smattering of snippets that may potentially hold together when assembled, but it is left up to you to figure out how to put the puzzle together and show that the pieces do not amount to a whole. The OP in this thread has said nothing after the initial post. There have been a couple of subsequent posts that were sort of ambiguous, where I couldn't really tell whether they were saying that it would make sense to use shielding on power cables, or that it wouldn't make sense.
As i said here before
https://www.audiosciencereview.com/...e-shielding-does-it-matter.20538/#post-699059
https://www.audiosciencereview.com/...e-shielding-does-it-matter.20538/#post-699059
@pedrob BTW. have you ever seen an Audiophile looking power cable on a peace of medical/laboratory gear?
A Rohde and Schwarz spectrum analyzer or scope for >100k€ Comes with a totally regular power cord
Tens of Millions dollars worth of professional reference test gear...
You see shielded power cables?
As with most audio discussions the dividing line comes down to "how much is enough". Most people here don't doubt the physics.
As far as FCC is concerned, if the equipment is good enough with a normal power cord, it is good enough with a normal power cord. If it needs a shielded power cord, then it needs to follow this part of its FCC report:
Of course, whether the FCC requirements are enough or not is up to personal interpretation. So I shall mark this as "Point of contention #1"
Most of the noise needs to be eaten up by the EMI filter anyway before the result gets low enough for usage with a normal power cord. And I would guess a couple capacitors and chokes are cheaper than a cable.
Next up is how far a high speed digital signal can travel down AC wiring and consequently the logicalness of the solution, which I shall mark as "Point of contention #2".
http://audiosystemsgroup.com/DigitalCableLoss.pdf
The author above has extracted data from cable datasheets. 4dB attenuation per 100ft @ 10MHz? 10dB @ 100MHz? That can be a lot or a little depending on situation. It is enough to screw over most computer interfaces for example, but Homeplugs have no problem pushing 2-digit MHz signals down your house wiring. And if your equipment is somehow 1dB too high from FCC limits, then that 1dB may be something to get rid of at all costs. But at this point it should be visible that a better EMI filter is going to a more practical solution.
As far as FCC is concerned, if the equipment is good enough with a normal power cord, it is good enough with a normal power cord. If it needs a shielded power cord, then it needs to follow this part of its FCC report:
Of course, whether the FCC requirements are enough or not is up to personal interpretation. So I shall mark this as "Point of contention #1"
Most of the noise needs to be eaten up by the EMI filter anyway before the result gets low enough for usage with a normal power cord. And I would guess a couple capacitors and chokes are cheaper than a cable.
Next up is how far a high speed digital signal can travel down AC wiring and consequently the logicalness of the solution, which I shall mark as "Point of contention #2".
http://audiosystemsgroup.com/DigitalCableLoss.pdf
The author above has extracted data from cable datasheets. 4dB attenuation per 100ft @ 10MHz? 10dB @ 100MHz? That can be a lot or a little depending on situation. It is enough to screw over most computer interfaces for example, but Homeplugs have no problem pushing 2-digit MHz signals down your house wiring. And if your equipment is somehow 1dB too high from FCC limits, then that 1dB may be something to get rid of at all costs. But at this point it should be visible that a better EMI filter is going to a more practical solution.
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