On Assuring Adequate AC Power
How to assess your audio system’s full AC power line requirements, and
how to determine whether your AC power line capacity is sufficient.
By Bryan Geyer
It’s important to
confirm that you have an adequate AC current reserve to optimally power your
audio system. This means more than just being confident that you can push the
volume up without causing a circuit breaker to trip. The function of a circuit
breaker relates to safety—not line quality or line stability. To assure that
your AC supply is not plagued by load-induced voltage drops it’s desirable to
verify that your audio system presents a drain that’s within the traditional
guideline for power line current density. The conventional “good design” limits
for this are as described here: http://www.powerstream.com/Wire_Size.htm.
You can generally
determine your household’s wiring gauge by inspecting your circuit breaker. The
current practice is to use AWG 14 Romex for a 15 ampere circuit, and AWG 12
Romex for a 20 ampere circuit. Because 20 ampere circuits are habitually routed
only to kitchen, bath, and laundry areas, it’s likely that your listening room
utilizes 15 amp circuits, hence AWG 14 wiring. By reference to the above, you
can see that the classic (it’s ultra-conservative) design guide for AWG 14 wire
is 5.9 amperes maximum. If it’s your intent to dedicate that specific circuit
exclusively to audio system use, then 5.9 amps max. current drain should be
your goal. If you exceed 5.9 amps you will potentially risk “modulating the
line”, meaning you could induce brief AC line voltage fluctuations due to the
inevitable load changes that your power amplifier imposes as its output shifts.
Regardless, I feel that some 50% more current drain is both safe and acceptable
if it truly reflects operation at full power output (with no other loads
on same circuit). That makes 9 amperes my personal full power ceiling
for AWG 14 in-wall wiring with 15 ampere AC circuit breakers.
To calculate your
system’s maximum AC current drain, sum the net power (as stated in Watts*)
consumed by your components, and divide the total by 120 Vac. That result will
approximate the maximum AC operating current. Component power consumption is
generally listed in the related performance specifications. Take care to assure
that power drain listed for your main amplifier(s) refers to power consumed
when operating at full power output into the applicable load impedance.
A NOTE: You can buy top quality molded SJT-type power
cords, AWG 14, 16, or 18, custom made to any length, at http://www.stayonline.com/molded-cord-configurator.aspx.
The price for a custom SJT power cord is low when compared to the price for a
high-end “audiophile-market” power cord, but it’s functionally identical, and
it will be properly sized, without unwanted excess.
*Watts apply when
considering most audio equipment, but not for AC motors, and not for Class D
power amplifiers. (Most self-powered subwoofers use Class D power amps.) Use
the Kill-A-Watt P4400 meter to measure the current drain or VA
(Volt-Ampere) consumption of turntable/tape motors and Class D amps.
BG (January 2019)
John J. Puccio, Founder and Contributor
Understand, I'm just an everyday guy reacting to something I love. And I've been doing it for a very long time, my appreciation for classical music starting with the musical excerpts on the Big Jon and Sparkie radio show in the early Fifties and the purchase of my first recording, The 101 Strings Play the Classics, around 1956. In the late Sixties I began teaching high school English and Film Studies as well as becoming interested in hi-fi, my audio ambitions graduating me from a pair of AR-3 speakers to the Fulton J's recommended by The Stereophile's J. Gordon Holt. In the early Seventies, I began writing for a number of audio magazines, including Audio Excellence, Audio Forum, The Boston Audio Society Speaker, The American Record Guide, and from 1976 until 2008, The $ensible Sound, for which I served as Classical Music Editor.
Today, I'm retired from teaching and use a pair of bi-amped VMPS RM40s loudspeakers for my listening. In addition to writing for the Classical Candor blog, I served as the Movie Review Editor for the Web site Movie Metropolis (formerly DVDTown) from 1997-2013. Music and movies. Life couldn't be better.
Karl Nehring, Editor and Contributor
For nearly 30 years I was the editor of The $ensible Sound magazine and a regular contributor to both its equipment and recordings review pages. I would not presume to present myself as some sort of expert on music, but I have a deep love for and appreciation of many types of music, "classical" especially, and have listened to thousands of recordings over the years, many of which still line the walls of my listening room (and occasionally spill onto the furniture and floor, much to the chagrin of my long-suffering wife). I have always taken the approach as a reviewer that what I am trying to do is simply to point out to readers that I have come across a recording that I have found of interest, a recording that I think they might appreciate my having pointed out to them. I suppose that sounds a bit simple-minded, but I know I appreciate reading reviews by others that do the same for me — point out recordings that they think I might enjoy.
For readers who might be wondering about what kind of system I am using to do my listening, I should probably point out that I do a LOT of music listening and employ a variety of means to do so in a variety of environments, as I would imagine many music lovers also do. Starting at the more grandiose end of the scale, the system in which I do my most serious listening comprises Marantz CD 6007 and Onkyo CD 7030 CD players, NAD C 658 streaming preamp/DAC, Legacy Audio PowerBloc2 amplifier, and a pair of Legacy Audio Focus SE loudspeakers. I occasionally do some listening through pair of Sennheiser 560S headphones. I miss the excellent ELS Studio sound system in our 2016 Acura RDX (now my wife's daily driver) on which I had ripped more than a hundred favorite CDs to the hard drive, so now when driving my 2024 Honda CRV Sport L Hybrid, I stream music from my phone through its adequate but hardly outstanding factory system. For more casual listening at home when I am not in my listening room, I often stream music through a Roku Streambar Pro system (soundbar plus four surround speakers and a 10" sealed subwoofer) that has surprisingly nice sound for such a diminutive physical presence and reasonable price. Finally, at the least grandiose end of the scale, I have an Ultimate Ears Wonderboom II Bluetooth speaker and a pair of Google Pro Earbuds for those occasions where I am somewhere by myself without a sound system but in desperate need of a musical fix. I just can’t imagine life without music and I am humbly grateful for the technologies that enable us to enjoy it in so many wonderful ways.
William (Bill) Heck, Webmaster and Contributor
Among my early childhood memories are those of listening to my mother playing records (some even 78 rpm ones!) of both classical music and jazz tunes. I suppose that her love of music was transmitted genetically, and my interest was sustained by years of playing in rock bands – until I realized that this was no way to make a living. The interest in classical music was rekindled in grad school when the university FM station serving as background music for studying happened to play the Brahms First Symphony. As the work came to an end, it struck me forcibly that this was the most beautiful thing I had ever heard, and from that point on, I never looked back. This revelation was to the detriment of my studies, as I subsequently spent way too much time simply listening, but music has remained a significant part of my life. These days, although I still can tell a trumpet from a bassoon and a quarter note from a treble clef, I have to admit that I remain a nonexpert. But I do love music in general and classical music in particular, and I enjoy sharing both information and opinions about it.
The audiophile bug bit about the same time that I returned to classical music. I’ve gone through plenty of equipment, brands from Audio Research to Yamaha, and the best of it has opened new audio insights. Along the way, I reviewed components, and occasionally recordings, for The $ensible Sound magazine. Most recently I’ve moved to my “ultimate system” consisting of a BlueSound Node streamer, an ancient Toshiba multi-format disk player serving as a CD transport, Legacy Wavelet II DAC/preamp/crossover, dual Legacy PowerBloc2 amps, and Legacy Signature SE speakers (biamped), all connected with decently made, no-frills cables. With the arrival of CD and higher resolution streaming, that is now the source for most of my listening.
Ryan Ross, Contributor
I started listening to and studying classical music in earnest nearly three decades ago. This interest grew naturally out of my training as a pianist. I am now a musicologist by profession, specializing in British and other symphonic music of the 19th and 20th centuries. My scholarly work has been published in major music journals, as well as in other outlets. Current research focuses include twentieth-century symphonic historiography, and the music of Jean Sibelius, Ralph Vaughan Williams, and Malcolm Arnold.
I am honored to contribute writings to Classical Candor. In an age where the classical recording industry is being subjected to such profound pressures and changes, it is more important than ever for those of us steeped in this cultural tradition to continue to foster its love and exposure. I hope that my readers can find value, no matter how modest, in what I offer here.
Bryan Geyer, Technical Analyst
I initially embraced classical music in 1954 when I mistuned my car radio and heard the Heifetz recording of Mendelssohn's Violin Concerto. That inspired me to board the new "hi-fi" DIY bandwagon. In 1957 I joined one of the pioneer semiconductor makers and spent the next 32 years marketing transistors and microcircuits to military contractors. Home audio DIY projects remained a personal passion until 1989 when we created our own new photography equipment company. I later (2012) revived my interest in two channel audio when we "downsized" our life and determined that mini-monitors + paired subwoofers were a great way to mate fine music with the space constraints of condo living.
Visitors that view my technical papers on this site may wonder why they appear here, rather than on a site that features audio equipment reviews. My reason is that I tried the latter, and prefer to publish for people who actually want to listen to music; not to equipment. My focus is in describing what's technically beneficial to assure that the sound of the system will accurately replicate the source input signal (i. e. exhibit high accuracy) without inordinate cost and complexity. Conversely, most of the audiophiles of today strive to achieve sound that's euphonic, i.e. be personally satisfying. In essence, audiophiles seek sound that's consistent with their desire; the music is simply a test signal.
Mission Statement
It is the goal of Classical Candor to promote the enjoyment of classical music. Other forms of music come and go--minuets, waltzes, ragtime, blues, jazz, bebop, country-western, rock-'n'-roll, heavy metal, rap, and the rest--but classical music has been around for hundreds of years and will continue to be around for hundreds more. It's no accident that every major city in the world has one or more symphony orchestras.
When I was young, I heard it said that only intellectuals could appreciate classical music, that it required dedicated concentration to appreciate. Nonsense. I'm no intellectual, and I've always loved classical music. Anyone who's ever seen and enjoyed Disney's Fantasia or a Looney Tunes cartoon playing Rossini's William Tell Overture or Liszt's Hungarian Rhapsody No. 2 can attest to the power and joy of classical music, and that's just about everybody.
So, if Classical Candor can expand one's awareness of classical music and bring more joy to one's life, more power to it. It's done its job. --John J. Puccio
Contact Information
Readers with polite, courteous, helpful letters may send them to classicalcandor@gmail.com
Readers with impolite, discourteous, bitchy, whining, complaining, nasty, mean-spirited, unhelpful letters may send them to classicalcandor@recycle.bin.
It’s important to
confirm that you have an adequate AC current reserve to optimally power your
audio system. This means more than just being confident that you can push the
volume up without causing a circuit breaker to trip. The function of a circuit
breaker relates to safety—not line quality or line stability. To assure that
your AC supply is not plagued by load-induced voltage drops it’s desirable to
verify that your audio system presents a drain that’s within the traditional
guideline for power line current density. The conventional “good design” limits
for this are as described here: http://www.powerstream.com/Wire_Size.htm.
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