An electrical engineer on how power cables can impact sound quality


Sharing an fascinating discussion of how the design of power cables can impact sound quality of an audio system from an electrical engineer that does analog design for audio equipment.

The HiFi Podcast with Darren and Duncan / Radio Frequency: The 800MHz Gorilla

The discussion of how power cables can impact sound quality starts at 80 minutes into the podcast

From the Podcast:

"If you have an engineering degree and you’re hearing this and you’re shaking your head and you’re saying this is nonsense, my response to you is that you’re logical. Based on what you have learned, I completely understand your response, but unfortunately, the way that power cables operate is not the way that we were taught in electrical engineering necessarily."

"Power cables were always thought of as series devices. If we add this 2 meter power cable to 2 miles of powerline, why does this 2 meter power cable make a difference?"

An intro into the theory behind why power cables work from the podcast:

"The power cable is not necessarily a series element of a system. The parallel elements [of a power cable] and way they interact with RF in the room in a common mode sense to ground is incredibly important." [Meaning in parallel to ground]

My paraphrase of the rest of the discussion. They get into far more detail: The configuration and materials used in a power cable matter because they affect a cable’s capacitance which in turn changes the cable’s impedance. Most importantly, the change in impedance impacts electrical signal differently across the frequency spectrum.

Two ways to get more details on this:

  1. Listen to the podcast starting at 80 minutes into the podcast. The discussion of how a cable's design impacts its ability to shunt RF to ground starts right there.
  2. Send a question to the hosts of The Hi Fi Podcast. You can find their email on their website.

Credentials of the creators of The Hi Fi Podcast:

Darren:
Darren is the designer of many products for Boulder’s PS Audio brand, most recently known for Stereophile’s choice as the 2020 “Analog Component of the Year,” the PS Audio Stellar Phono preamplifier, and the incredibly well-reviewed new Stellar M1200 tube hybrid mono amplifiers.


With a career as an analog and digital circuit designer spanning two countries and several of the most well-known brands, Darren brings much experience to the table. He earned his EE and worked for both Bowers & Wilkins and Classe Audio before coming to Colorado, and also, before turning 30.

He is the designer of the PS Audio Stellar Phono phono preamp

Duncan:
Duncan has recorded 150+ bands, has published 450+ articles, columns and blogs and is an experienced DIYer when it comes to audio equipment and speakers. He met Darren when working as the Retail Sales Manager of Boulder’s PS Audio, and the two collaborated on an audiophile recording and concert series called “Invisible Audience,” not to mention the weekly hikes in the mountains. He is a mastering engineer, cable designer and musician, avid fly fisherman, bike polo enthusiast, husband and dad in his “free time.”


But what truly gives him a useful perspective for the podcast is his day job as a testing technician for the world’s largest online re-seller of high end audio, The Music Room. Over years in this role, he has listened to and evaluated thousands of the finest products from all over the industry and throughout high end audio’s extensive history.

calvinandhobbes
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High end power cables are cool things that appeal to the audio nut. If you like them buy them. I strongly doubt they make any difference in sound; the nuance here is to avoid the really cheap stock ones. Audio Science Review is the most clearheaded opinion on things like this. The fact that many of the people who like fancy cables are tube enthusiasts says it all.

I don’t fully agree.

For one I am not a power cable “believer”, but I suppose if I saw one make a difference then I could be.

Secondly, many tube amps in particular have massive reserves of energy. One can turn off the power switch and they play for many seconds with the same authority as with the power switch on. If the amp was not buffering the energy as a DC in capacitors, then we would hear 60 Hz coming out as the rails were pulsating with the incoming power. But that is pretty rare… I have not heard that happen myself.

The preference of tube amp harmonics is not really something that would preclude ASR membership. If one can show that SS harmonics are creating “off putting” sounds, then if those metrics show that tubes do not have those harmonics… then that it is also providing a science based reason why tubes might be preferred.

So let’s not convolve tubes with power cords, and lets not devalue objective measurements to be something that cannot be used to describe the sound of an amplifier in a system.

Lastly there are almost no measurements that show that an amplifier works better with such-n-such brand of a power cord. If the power cord makers showed a lower noise spectrum at the end of the cord, or that the amplifier had a more stable DC rail voltage, then it would be an easy way to claim that a difference exists and that there is a rational reason to consider their purchase…

I think that the power cords look cool, and have cool names, but I doubt they do much. And I await being convinced by something more than personal testimony and story-time lore.

For folks that believe in only considering measurements without listening, this is what an electrical engineer who works for Audio Precision (a manufacturer of audio measuring equipment)and a former governor of the Audio Engineering Society (AES) has to say about "What The Specs Don’t Tell You… And Why"

https://youtu.be/2V6YN-mshmY

There's a reason it was titled  "What The Specs Don’t Tell You… And Why" and not 

"What The MEASUREMENTS Don’t Tell You… And Why".   

How come no one talks about results from an emi measuring device.  I have one and it's remarkable how much noise is created when various electrical components are being used in the house.  A refrigerator compressor adds alotta noise throughout the house.  
 

Has anyone else used an emi measuring device and found it helpful to assess their internal situation?