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Why an AC Power Cord cannot make a difference

So HaveMeterWillTravel's statement about eliminating this "mains phase inversion induced common mode noise" by using a different power cord actually means you have to modify a power cord by cutting it open and swapping the hot and neutral wires?
Have too? No.


I'm going to show off the depth of my understanding of basic electrical theory by asking another question: instead of cutting open the ac cord and swapping the wires, wouldn't it make more sense to pull the wall receptacle out and swap the wires there?
I would never advocate doing this. One is now risking a house fire.
If that actually fixes this problem HaveMeterWillTravel has identified, wouldn't it make OP's assertion "an AC Power Cord cannot make a difference" strictly true - assuming your ac wall outlet is wired correctly?

It is not an issue of the outlet nor the cable being incorrect, per say. They most likely are. Rather, if there is an issue in the equipment, then it may be the most practical method for an end user.

Myself? I just pitch the power supply and get a correct one.
 
So HaveMeterWillTravel's statement about eliminating this "mains phase inversion induced common mode noise" by using a different power cord actually means you have to modify a power cord by cutting it open and swapping the hot and neutral wires?

I'm going to show off the depth of my understanding of basic electrical theory by asking another question: instead of cutting open the ac cord and swapping the wires, wouldn't it make more sense to pull the wall receptacle out and swap the wires there?

If that actually fixes this problem HaveMeterWillTravel has identified, wouldn't it make OP's assertion "an AC Power Cord cannot make a difference" strictly true - assuming your ac wall outlet is wired correctly?
These days, yes, if the plug is molded on, you have to cut it off, strip wires, and put a new plug on it because of polarized plugs and outlets. However... most of the cheap wallwarts I have plug in directly rather than having a cord and don't have polarized prongs, so you can just physically turn them the other way. Easy peasy.

Yes, you could swap the wall socket's wires after ensuring the breakers are off! :cool:
 
If that actually fixes this problem HaveMeterWillTravel has identified, wouldn't it make OP's assertion "an AC Power Cord cannot make a difference" strictly true - assuming your ac wall outlet is wired correctly?

"Cannot" is an absolute statement, and the OP's measurement were no sufficient to justify scientificly. Especially in light of several obvious examples of where it most definately will.
Perhaps the best and most obvious example which people just know but always forget is simply the cable length.

Instead of having some introspection, devout acolytes react with the cognitive dissonance of both having admitted it makes a difference while contiuing on making the same absolutist declaration that it doesn't.
 
Back in the old days, we'd just reverse the plug to reduce noise. Harder to do now because of polarized plugs (one blade is larger than the other), so the easiest way is to take the plug off the power cable, then rewire swapping black for white.
Because power transformers are not symmetrically wound with respect to the chassis, there is more leakage (capacitance) from one terminal than the other. Skilled circuit designers know this, so they connect the AC Neutral wire to the terminal with more leakage. That way because the terminal and the chassis (which is connected to the Safety Ground) are at almost the same potential there is less leakage current.
 
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To defend the use of the extravagant power cords, some audio crazies think that the last few feet of the wire closest to the amplifier are important to get right, and all the wiring supplying that last few feet makes no difference in sound quality. Go figure. It's an artifact of belief-based audiophillia.
 
You construct a scenario where a faulty component allows a type of AC noise into the signal chain, then you posit that using a kludged AC cord (which according to you isn't available at retail) would remedy the noise. Can you really then say "See? AC cords DO make an audible difference in sound quality"?
The orientation of an AC cord can in some special cases affect noise. Not "sound quality" in any other sense. This is as trivial as, "If you have a 4 foot run to the wall socket, there will be a difference between a 3 foot cord and a 5 foot cord."

So despite a bit of attempted cleverness, the point remains, AC cords have no effect on sound quality.

My spider senses are tingling all over . Again.
Understood. But don't attribute to malice what can be more easily attributed to...
 
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But the RCA barrel should be attached to the metal chassis (at it's connector)
No it isn't, and some RCA come with a spacer/washer to prevent that.

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In any case, secondary ground should not be directly connected to mains earth and that's a fact that is enforced in safety code. Notice this statement implies that chassis in class-I appliance should not be treated as secondary ground.
 
BTW for those looking for an easy way to swap mains polarity, just use a USA to UK adapter like this or whatever. Notice that w.r.t. to ground pin positioning, the mains and neutral are swapped between USA and UK (and I'm sure other combinations of countries). And these universal adapters don't give a **** so left pin goes left and right pin goes right. Needless to say, this is nightmare fuel for those educated in electrical safety, and if you own an overseas power strip or whatever equipment and is using such an adapter that causes the reversed polarity, stop using the equipment now and rewire it properly with the correct plug.

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Because power transformers are not symmetrically wound with respect to the chassis, there is more leakage (capacitance) from one terminal than the other. Skilled circuit designers know this, so they connect the AC Neutral wire to the terminal with more leakage. That way because the terminal and the chassis (which is connected to the Safety Ground) are at almost the same potential there is less leakage current.
Yes. But with a Type II power supply where there is no safety ground this can not be done.
 
BTW for those looking for an easy way to swap mains polarity, just use a USA to UK adapter like this or whatever. Notice that w.r.t. to ground pin positioning, the mains and neutral are swapped between USA and UK (and I'm sure other combinations of countries). And these universal adapters don't give a **** so left pin goes left and right pin goes right. Needless to say, this is nightmare fuel for those educated in electrical safety, and if you own an overseas power strip or whatever equipment and is using such an adapter that causes the reversed polarity, stop using the equipment now and rewire it properly with the correct plug.

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I completely forgotten about the phase inversion, and only check to ensure 220-2240V operation of devices when traveling.
 
Thanks for your replies! :) I'll offer a few comments:



You construct a scenario where a faulty component allows a type of AC noise into the signal chain, then you posit that using a kludged AC cord (which according to you isn't available at retail) would remedy the noise. Can you really then say "See? AC cords DO make an audible difference in sound quality"?

The negative side effects of a Type II power supply is not a constructed scenario, especially given the expansion of their use in recent years.
 
If power cords could affect S.Q., once ampacity requirements are met, what would be the mechanism by which they might do that, beyond acting as antennas for picking up RF noise which might upset equipment operation?
 
Actually it does. Or rather, it is part of it.

Unless you wish to modify your equipment internally, changing the common mode phase alignment is easiest done with the power cords.
Tell me exactly how that works without wiring a cable incorrectly. Think UK Power leads which have very specific (and legal) wiring requirements for live and neutral, including wire colours.

Also, please let me bring you back to:

And while we are about it, lets keep it to the type of cable difference other than "those basic requirements to make it work correctly and safely" which are not really what the thread is about.
 
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Understood. But don't attribute to malice what can be more easily attributed to...

I don't know - it's increasingly feeling a lot like enemy action. This guy is neither stupid nor ignorant regarding electronics, but the argument doesn't seem to be in good faith at the moment.
 
I don't know - it's increasingly feeling a lot like enemy action. This guy is neither stupid nor ignorant regarding electronics, but the argument doesn't seem to be in good faith at the moment.
It seemed like a deliberate but misplaced moving of the goal posts. Maybe due to a very literal reading of "Power cable cannot make a difference".

Almost all of us know that from the start, Pavel's OP was addressing the topic of "Why expensive/snake oil power cables will not make a difference to sound quality compared to the exact same setup using a $3 Monoprice power cord".

But if someone wanted to read the title literally, whether to be intentionally argumentative or because they cannot extrapolate the actual topic of interest from it, then I get why one might argue from the stance of "Well, if there is a grounding or mains wiring defect, than here is an instance where the power cable can be modified to make a differnece".

So maybe it just needs to be repeated plainly and bluntly: when discussing pwoer cables not making a difference, it is in regard to an otherwise properly working system and comparing a standard power cord (wired properly) to an expensive/snake oil power cord (also wired correctly).
 
It seemed like a deliberate but misplaced moving of the goal posts. Maybe due to a very literal reading of "Power cable cannot make a difference".

Almost all of us know that from the start, Pavel's OP was addressing the topic of "Why expensive/snake oil power cables will not make a difference to sound quality compared to the exact same setup using a $3 Monoprice power cord".

But if someone wanted to read the title literally, whether to be intentionally argumentative or because they cannot extrapolate the actual topic of interest from it, then I get why one might argue from the stance of "Well, if there is a grounding or mains wiring defect, than here is an instance where the power cable can be modified to make a differnece".

So maybe it just needs to be repeated plainly and bluntly: when discussing pwoer cables not making a difference, it is in regard to an otherwise properly working system and comparing a standard power cord (wired properly) to an expensive/snake oil power cord (also wired correctly).
Which is what I was intending with my statement in post #134 re-quoted in post #174 above.

Perhaps I was just not blunt enough.
 
Yes, you could swap the wall socket's wires after ensuring the breakers are off!

Or you could split the difference with an Equitech and put 1/2 the voltage on the hot and neutral going to the gear.

Yeah, I confess, I have one.

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Bought from Shock City Studios (an appropriate name, I suppose) via eBay as they ugraded to "whole house" balanced power.
 
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