Magnetic field observations from power cables

[Pdxwayne]

In one recent power cable thread, it was mentioned that power cable would cause issue to RCA cables if those are placed next to each other.

I became curious about magnetic field of OEM cable (16awg x 3) vs those thicker, lower AWG (12 awg x 3) premium power cable (typically less than $50 for 6ft) sold in Amazon.

I found one meter, TriField Meter Model 100XE in my storage. Thus I decided to check OEM (16 awg) and aftermarket (12 AWG) power cables. I checked the magnetic field when connected to powered on Parasound A23 stereo amp.

I was expecting lower field stength from thicker cable but the opposite was observed.

The meter's needle starts moving when the thicker aftermarket cable is about 7cm (from bottom of cable) to the sensors of meter.

With OEM cable, the meter's needle starts moving when it is about 3cm (from bottom of cable) to the sensors of meter.

What would be the reasons for the difference?

Thanks!

Here is the picture of cables for reference:

 

[mansr]

I was expecting lower field stength from thicker cable but the opposite was observed.

No surprise there. The thicker cable (likely) has greater conductor spacing, so the fields will not cancel as well at close distances.

 

[Pdxwayne]

No surprise there. The thicker cable (likely) has greater conductor spacing, so the fields will not cancel as well at close distances.

Thanks! In this case, would it mean the OEM is actually better, in term of EMI, when we have a lots of cables going behind the stereo racks?

 

[beren777]

No surprise there. The thicker cable (likely) has greater conductor spacing, so the fields will not cancel as well at close distances.

You just single-handedly created a new audiophile market segment for "ultra-slim balanced field power cables." The race will be to see how small and how intertwined the wiring can be to "best cancel out the negative effects of power-related EMI on your audio system."

 

[solderdude]

Thanks! In this case, would it mean the OEM is actually better, in term of EMI, when we have a lots of cables going behind the stereo racks?

EMI is usually common mode. Mains is differential mode. There is a big difference between these modes.

As long as you are not plagued with audible hum it's all fine and there is no need to check anything. RCA cables that are well made (good shield) should already be fine. Balanced signals are even better and you can easily lay cables on top of each other in that case.

 

[Pdxwayne]

EMI is usually common mode. Mains is differential mode. There is a big difference between these modes.

As long as you are not plagued with audible hum it's all fine and there is no need to check anything. RCA cables that are well made (good shield) should already be fine. Balanced signals are even better and you can easily lay cables on top of each other in that case.

Good to hear that!

 

[JustJones]

I use active speakers and wrap the AES3 and mains cable together in a mesh sleeve for aesthetic reasons and haven't had any problems.

 

[egellings]

I would think that the radiated magnetic field in a power cord would be minimal, since two wires side by side have exactly the same current flowing in opposite directions, which would cause cancellation.

 

[Pdxwayne]

I would think that the radiated magnetic field in a power cord would be minimal, since two wires side by side have exactly the same current flowing in opposite directions, which would cause cancellation.

Here is what I got for both wires, when placed on top of the sensors, when my Parasound A23 is turned on. It went all the way to the right, passed the 100 max value.
I was using the 0 to 100 option.

I get nothing too significant (~20 to 25) when checking the line for Topping L30.

 

[Speedskater]

Bill Whitlock (retired Jensen Transformer) writes about this in his AES seminary paper.
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

 

[Rockdog]

EMI is usually common mode. Mains is differential mode. There is a big difference between these modes.

As long as you are not plagued with audible hum it's all fine and there is no need to check anything. RCA cables that are well made (good shield) should already be fine. Balanced signals are even better and you can easily lay cables on top of each other in that case.

Isn't this really the bottom line? I ask that in sincerity. We hear so much marketing and snake oil hype about EMI, but is it not true that if you have everything connected, even the volume cranked up, and you pause your source, that if you hear no audible hum with your ear up to the speaker, you're good to go?

I've heard the case made that sometimes EMI only rears its ugly head when music is playing and signal is traveling through cables, rather than at idle. Therefore, the low cost speaker cable sounds fine on idle, its only when music is playing that the $1000 cable makes a difference! I can't see how that would be the case.

 

[Pdxwayne]

Isn't this really the bottom line? I ask that in sincerity. We hear so much marketing and snake oil hype about EMI, but is it not true that if you have everything connected, even the volume cranked up, and you pause your source, that if you hear no audible hum with your ear up to the speaker, you're good to go?

I've heard the case made that sometimes EMI only rears its ugly head when music is playing and signal is traveling through cables, rather than at idle. Therefore, the low cost speaker cable sounds fine on idle, its only when music is playing that the $1000 cable makes a difference! I can't see how that would be the case.

I hear a slight hum out of my speakers when nothing is playing. DAC direct to amp. That is not solved with different power cables. Not solved by using power conditioner. Even with nothing connected to amp, just amp to speakers, I hear slight hum.....

Strangely, once my DAC signals are going through minidsp, then to amp, the hum is now replaced by hiss.....

 

[Rockdog]

I hear a slight hum out of my speakers when nothing is playing. DAC direct to amp. That is not solved with different power cables. Not solved by using power conditioner. Even with nothing connected to amp, just amp to speakers, I hear slight hum.....

Strangely, once my DAC signals are going through minidsp, then to amp, the hum is now replaced by hiss.....

Interesting.. I have a minidsp SHD. Its dead quiet all around, though there is some very faint hiss. Have to put my ear right on tweeter to hear it. I'm thinking most all components have at least some perceptibly faint audible noise floor.. though I don't know that for sure.

Isn't hum almost always electrical line noise? (Ground hum) wonder if your minidsp changes internal power flow, powers on a chip or circuit changing internal grounding structure, only when playing music?

 

[Pdxwayne]

Interesting.. I have a minidsp SHD. Its dead quiet all around, though there is some very faint hiss. Have to put my ear right on tweeter to hear it. I'm thinking most all components have at least some perceptibly faint audible noise floor.. though I don't know that for sure.

Isn't hum almost always electrical line noise? (Ground hum) wonder if your minidsp changes internal power flow, powers on a chip or circuit changing internal grounding structure, only when playing music?

Strange to me too. Minidsp hiss is when nothing is playing. Have to place my ear near speaker to hear it. I can't hear the hum nor hiss from my seat.

 

[Maki]

Looks like I'm replacing all my thick $10 amazon power cords with thin $6 amazon power cords. I expect to hear a huge improvement in soundstage, PrAT, and blackness of background.

 

[sailor2005]

Looks like I'm replacing all my thick $10 amazon power cords with thin $6 amazon power cords. I expect to hear a huge improvement in soundstage, PrAT, and blackness of background.

You forgot that a veil will be lifted.....

 

[solderdude]

I hear a slight hum out of my speakers when nothing is playing. DAC direct to amp. That is not solved with different power cables. Not solved by using power conditioner. Even with nothing connected to amp, just amp to speakers, I hear slight hum.....

This is the amp itself doing the hum. When you only hear it with your ear against the speaker and not anymore a meter away it is below audible threshold. It will be masked by music anyway.

Strangely, once my DAC signals are going through minidsp, then to amp, the hum is now replaced by hiss.....

replaced by hiss or drowned by hiss ? Is that hiss only audible with your ear against the speaker ?
Is the hiss 'white noise' or does it consist of all kinds of nasty sounds ?

Isn't this really the bottom line? I ask that in sincerity. We hear so much marketing and snake oil hype about EMI, but is it not true that if you have everything connected, even the volume cranked up, and you pause your source, that if you hear no audible hum with your ear up to the speaker, you're good to go?

Hum (50-60/100/120/150/180 Hz) yes.

I've heard the case made that sometimes EMI only rears its ugly head when music is playing and signal is traveling through cables, rather than at idle. Therefore, the low cost speaker cable sounds fine on idle, its only when music is playing that the $1000 cable makes a difference! I can't see how that would be the case.

In some rare cases where the speaker cable is picking up RF there is the possibility the amp in question could do some weird stuff.
Screened cable could help in that case but the screen would have to be connected to enclosure of the amp. On top of that part of the 'antenna' won't be shielded as wiring in the speakers itself is never shielded.

Then there are ground loops but these have nothing to do with speaker or mains cables but currents flowing through the screen of RCA interlink cables. Filters won't help here only breaking the ground loop will.

 

[Pdxwayne]

..........
replaced by hiss or drowned by hiss ? Is that hiss only audible with your ear against the speaker ?
Is the hiss 'white noise' or does it consist of all kinds of nasty sounds ?
.........

I would say replaced by hiss. More like white noise that is audible when my ear is a few inches away from speakers. No nasty noise I could sense.

Thanks!

 

[solderdude]

When it isn't influenced by faffing about with cables or re-positioning of things and is constant it is simply background noise from the used devices.
Not many systems are completely quiet when one holds the ear against the tweeter or woofer. As long as you don't hear anything at the listening position it's fine for what background noises is concerned.

When it is cable related moving around a few cables would immediatly change the hum. When it doesn't it is not an issue.

 

[Pdxwayne]

When it isn't influenced by faffing about with cables or re-positioning of things and is constant it is simply background noise from the used devices.
Not many systems are completely quiet when one holds the ear against the tweeter or woofer. As long as you don't hear anything at the listening position it's fine for what background noises is concerned.

When it is cable related moving around a few cables would immediatly change the hum. When it doesn't it is not an issue.

Yes, I believe the slight hum issue is inherent to the amp. The hiss produced when connected to minidsp might be just loud enough to drown out the slight hum.

Maybe my living room speakers are more sensitive. I can still barely sense hiss/hum from as far as about 2 ft away. My computer room speakers are connected to same amp model and I need to place my ear right next to the speaker to hear hum. Either case, no issue at all from listening position.

Thanks!