Testing Open Power Cord interference in Interconnect Cables

Explanation of why even an unterminated AC cable can cause interference in audio cables (and why it doesn't matter in reality).

[TexJJN]

Yet another video where I am left in awe of your exceptional educational approach and ability. I originally came to the channel for the reviews, but I am now realizing the true gold is the science and engineering we are being exposed to. Thank you so much for this.

[bbfrid]

I like the way you explained this without any defensiveness or derision towards others. Good video.

[jhensjh]

Wonderful video Amir. A more dramatic example of the current in an open circuit conductor is found in long distance high voltage (200kV+) power lines. When a several hundred mile long high voltage line that has been de-energized is re-energized with no load on it, the current rushing into the line solely due to the capacitance between the line and ground can be large enough to trip the circuit breakers. One way this is controlled is to temporarily connect an inductive load parallel to the line to reduce the charging current until the line has been fully charged.

[danielgeiger]

Great video and demo! Hats off. I chuckled at quip about learning things in college out of context. Reminds me of statistics. In class it's all a big woopdie doo, then you start gathering data and suddenly you see how it manifests (distributions, homoscedasticity, etc.).

[tombarber]

Apparently this video was motivated by statements made by Danny at GR Research, who evidently criticized Amir's testing by claiming that there must be an appreciable level of current flowing in a cable in order for that cable to transmit/leak electromagnetic fields (into the space surrounding the cable) that can cause problems for other, nearby cables. Amir has thus made it clear that Danny simply didn't know what he was talking about. Which shouldn't surprise anyone, given that not very long ago Danny did a video where he connected several different speaker cables to the input of a radio receiver and used the signal strength meter on the receiver to show that speaker cables differ in terms of their ability to pick up stray electromagnetic fields. Implicitly he was claiming that the differences among speaker cables in this respect translate to differences in the sound quality you get with the different cables when they are used to connect speakers to amplifiers. Even if you designed an antenna for the express purpose of picking up the stray 60 Hz signal that is common in any household, and connected this antenna directly to any typical home speaker, it is exceedingly unlikely that the SPL output by the speaker, for that 60 Hz signal, would be loud enough for you to hear it. Speaker sensitivities are nowhere near great enough for this, which is why we need amplifiers to step up the voltage to meet the requirement of the speaker in terms of sensitivity, and to supply the current that the speaker will draw when delivered that higher voltage. If you run the 60 Hz signal picked up by an ordinary speaker cable through an amplifier, it is all but certain that you'll be able to hear the 60 Hz hum through the speaker connected to the amplifier. Perhaps Danny was confused and thought he was showing why speaker cables make lousy interconnects. The thing is, he pretended to be answering a question that is very different from the question that he answered. Two completely different questions, one that he pretended to be answering while he actually answered the other question. It was bizarre to say the least.

[jaakanshorter]

You just reminded me of the late 90s, with my first stereo, when I figured out I needed to either disconnect loose cables or connect them to another device.

[riccitone]

This has been SO educational. Lays to waste a lot of misconception. Very directed and applicable to so many audio concerns and discussions. Thank you for taking the time to teach and demonstrate current and fields so comprehensively 🙏🏼

[CatchyNameF]

As always scientific, educational and comprehensive.

[davidstein]

Thanks Amir for another informative & quick lesson on power cords.

[johnsmith]

Perfect presentation of some fascinating subtly in fundamentals, this is like a head & neck massage for my mind. I particularly like the points at which you express amusement. Thanks Amir!

[kyron]

Keep these videos coming, long or short they're always interesting. I am an electrical engineer audiophile so maybe that's why..

[dcrook]

After 4-5 yrs of reading ASR forum subjects and using the info when appropriate, I've, surprisingly, just discovered you've got the great YouTube CH. 👍 It's great to put a face with a name! Will view your backlog this coming weeks/months.
Kudos 💪

[markrhino]

Matter of fact. Not condescending or patronizing. No personal insults. And no conflict of interest (ie not selling anything). I know who i prefer listening to. Also, comments against have not been edited/removed.

[martytoo]

Love this one. Such an unexpected answer. But then again I was trained as a chemical engineer, not an EE. Dang it all or damn it all or perhaps Dan it all!! :-)

[scottwheeler]

Here’s the problem. You are using a low end non audiophile power cord with a high end cable. They lack synergy. You need a high end audiophile power cord, one that costs 10K or more to get the synergy and then you will get blacker blacks in your back ground as well as more Blume and jazzier attacks on your transients as well as 23% greater musicality.

[nathandaniels]

I’ll be honest, I’m not a huge fan of some of your reviews and especially not your fan base.

That said, I really appreciate the way you handled this video, especially knowing the context behind it. It might be helpful when reviewing future power cables to include a short interference test with a small load on the cable, but you’ve nonetheless made your point well.

[JKGarageBMW]

Whoever contests this test does not understand that a cable plugged into an electrical source becomes an antenna and if you want to show how effective the cable is at squashing noise then that's the test to do. If you want to show how good OTHER equipment is at sinking noise, plug the cable in. Good job Amir.

[JKGarageBMW]

As someone who designs and constructs motorsport harnesses used in automotive applications AS A HOBBY, where ignition coils discharge many 10s if not 100's of kv into a spark plug, generating an ungodly amount of noise in the ground plane, it's clear Danny doesn't understand how cables work from a fundamental stand point. The first thing you learn when dealing with these types of systems and variable reluctance sensors (AC current) or hall-effect sensors (square wave DC current) is that you shield the signal wires on ONE END (preferably a common point for all sensors so as to not offset the reference voltage). Not both ends. That would make the cable "not plugged in" on one end like Danny was making fun of. By tying the shield to ground on both ends you create a ground loop... which is why balanced audio circuits and isolation exist. It's literally part of audio design that he seems to dismiss. When dealing with 5v-12vdc sensors its extremely easy to cause false triggers with capacitor discharge ignitions or even with conventional induction ignition coils. It concerns me that a company selling products touting the solution does not understand RFI/EMI at a very, very fundamental level.

[tallpaull]

Why do you need to test with power cables not hooked up? Why not just test it the way it is used, plugged into the unit and powering the unit?

[alanross]

Very interesting. It’s counterintuitive. No doubt this will agitate the usual suspects. Good explanations like yours will hopefully save music enthusiasts a lot of money that will be better put to better recordings and equipment that actually makes a difference.