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:
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.
They so talk a bit about the products of their respective employers, but most of their discussion is about their work and their own experimentation. I love that their discussions are inspired by their listening but grounded in the science. It's interesting to hear that even with their education and hands-on experience, sometimes they can't explain an audible difference in sound quality. |
@erik_squires That's part of their explanation, but the cable configuration and dielectric material affects capacitance of the power cable. How this changes the impedance of the cable is part off how power cables are designed to shunt RF to ground more effectively. This is due to impedance hindering the transmission of electrical signals at higher or lower frequencies to differing degrees. |
To repeat what @jl35 said, PS Audio does not sell power cords. |
From the website of a manufacturer of industrial cables:
A listing of dielectric constants: http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/diel.html Two dielectric materials used in audio cables, teflon and cotton (with a high percentage of air relative to solid material) have lower dielectric constants closer to that of air and to the ideal which is a vacuum. |
@noske @larsman @vanson1 In respect to using less expensive power cords, one thing that Darren and Duncan have said on their podcast is that PS Audio supplies a decent but not particularly expensive power cord for their components. This stock power cord was chosen because it provided a balanced performance for multiple aspects of sound quality. Though improvements can clearly be had over the stock power cord, they also said that it can take a bit of money to get a power cord that is clearly better in all respects. Apparently at a more moderate price point, power cords can improve specific aspects of sound quality but at the detriment to other aspects. My takeaway from that comment was that listening to a power cord is vital & that a more expensive power cord is not necessarily better than one that is less expensive. What parts of sound quality someone is seeking to improve would be a important consideration in deciding whether to buy a more expensive power cord at all and also in determining which power cord to choose. |
@larsman I completely agree with manufacturers not wanting to spend excessive amounts of money on power cords. From a business perspective, this bumps up the "base" cost of their components. I agree also that people who are into cables might want to use their preferred cables. Another activity that I spend money on is bikes. Saddles (seats) on even fairly expensive bikes are often throw-away items since everyone has a different preference for what saddles they prefer. I do wonder why audio equipment manufacturers don't suggest power cords that work well for their equipment (or perhaps several power cords from different brands depending on the sonic characteristics that a buyer might be looking to optimize). Perhaps because they are too busy designing equipment to be testing power cables which are not part of their core technical expertise? |
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" |
@larsman Makes sense. I imagine customers (especially audio equipment customers) complain about all sorts of things. |
