RSAD Alethias C7 Power Cord Review

The purpose of this review of the newly released Ridge Street Audio Designs (RSAD) Alethias C7 Power Cord is at least twofold.  Foremost, it is to share the wonderful experience I've had over the past couple of weeks with the Alethias C7 in my reference system here at Ultra Fi so that others might experience the same and, secondarily, it is to provide fellow music lovers and audiophiles some insight into how Robert Schult, proprietor of and designer at RSAD, arrived at the Alethias C7.

Less obviously, through doing the later, it is also my hope that I might provide some guidance in how one might set about selecting a power cord for use with a computer or, more specifically, the unibody Mac mini.  Finally, and likewise through the later, it is further my hope that readers will gain some appreciation for the toil, attention to detail, and creative genius of one who I am proud to call my friend - Robert Schult.


I've been an avid proponent of computer audio for the better part of a decade now and my use of the Apple Mac mini as a dedicated music server stretches back in time somewhere in the neighborhood of seven years to the introduction of the solo core G4.  More recently, I've used the G5 mini.  All of these minis make use of an external switch mode power supply (SMPS) supplying 18.5 volts and having a capacity in the neighborhood of 110 watts.

During this period, I developed a little known product called the ECM for use in addressing the shortcomings of these SMPS.  The ECM, in its final form, comprised two successive 1,000 VA toroidal transformers in a balanced arrangement having an additional secondary winding coupled to a circuit that is used to tuned the Q of transformers to provide optimum rejection of switched mode frequencies coming back out the of these SMPS and finding their way into the power lines, further making their way into audio components typically found in one's system, e.g., digital-to-analog converter, preamp, amplifier(s), etc.

If you think you've experienced the same using an isolation/balanced transformer or some other form of power conditioning - you simply haven't.  There's on the order of 40 dB more rejection using the approach I just detailed.

For a short while, the notion of this approach was alluded to on the Plitron transformer website which was, in part, conformation of my idea.   However, it was later pulled as I believe they were seeking patent protection for the same in a medical application.

Battery and linear supplies were also developed and experimented with during this time period, still none preserved detail and had the dynamic impact of the ECM.

In the end, I authored a whitepaper entitled "The Computer As A Noise Generator" detailing this approach and used two Ridge Street Audio Designs Alethias Signature Power Cords with the ECM - one intermittent the mini power supply and the ECM and one between the ECM and the wall.

To provide readers with some perspective on the economic ridiculousness (yea, I still watch a bit of MTV every once in a while) of this approach - that makes for an $8k arrangement for plugging a $800 Mac mini into to get your system to sound its best.  It is easy to see why the ECM was relatively unknown and largely a commercial failure.  Yet, it sounded good...and Robert was right there with me.

But, so much is the mantra here at Ultra Fi and Ridge Street Audio, in that we both are committed and endeavor to leave no stone unturned when it comes to trying different approaches to achieve musical happiness, and, in this regard, Robert and I are kindred spirits.

In 2010, with the advent of the unibody Mac mini things got turned on their ear - pun intended.  Gone was the external power supply and, along with it, the need for the ECM and its associated power cords.  Now, the ECM was of no benefit as, in stark contrast to its predecessors, the unibody mini now incorporates an energy savings power supply having a capacity of less than 100 watts and at 12 volts.  Further, somewhat to the chagrin of many audiophiles, the unibody mini now had a C7 power connector that prevents the ready use of many an audiophile power cord.

For the edification of some readers, the C7 connector is a sort of two pin figure 8, whereas the typical  three pin IEC connector audiophiles are familiar with is the C14.

But, such things are readily overcome with the Internet and C14 to C7 adapters are available and cheap. see:

Similarly, for the sake of completeness, the following link from Apple does a nice job of chronicling the differences between the various Mac mini models:

So, despite Robert cautioning me that in his experience such adapters can be somewhat sonically detrimental, I forged ahead and conducted a power cord shoot out on the unibody mini.  More than 30 commercially available power cords were included in this shoot out ranging in price from less than a hundreds to some costing several thousand dollars - also included were several cords having a C7 connector and specifically intended for use with the unibody mini.  What I found was most interesting.

Generally speaking, in my reference system, most of these cords sounded colored and ultimately inferior to the stock Molex cord that comes with the unibody mini.  Further, these colorations proved to be, at best, a lateral or, at worst, a backward move rather than a genuine improvement.  In one particular instance, one of the C7 connector bearing cables sounded grossly colored - so much so, in fact, that it became almost laughable how anyone could even begin to appreciate it in any system. 

At this point in time, I became a bit frustrated with the whole thing and reconciled myself to using the stock Molex cord for the time being.  Incidentally, although the C7 connector can be plugged in one of two ways, there is a correct orientation.  Experiment, it is easy to identify the correct orientation.

One day while reading a posting on Audiogon I noticed someone was using the Nordost Purple Flare power cord for their unibody mini and I filed that away in my memory.  Later that day, I gave Robert a call about something or other and I recanted my bewilderment with the power cord shoot out and mentioned the Nordost Purple Flare.  To make a long story short, it wasn't but a couple days before we both had Purple Flare power cords on our minis.

The Purple Flare was an improvement over the stock Molex cord, though now in hindsight not dramatically so (more on this later).  Generally, there was an increase in presence and it was easier to make out what singers were singing.  Sound staging was much the same as were the high and low frequency extension.  Front to back layering was improved and the sense of depth was a bit better.  All in all, kind of a no brainer for $160 delivered overnight from Music Direct.  Lord knows I've spent more and got less...

So, Robert and I began theorizing and postulating as what it could be that allowed the Purple Flare to shine above all the other power cords when used on the unibody mini and, a couple of things came to mind.

First off, what with it's SMPS, the mini presents a dramatically different load that the typical audio component.  The mini has a rather large current demand at turn on and, once up and running, generally coasts for the most part.  Thus, if one builds a linear supply for the mini, such a supply must be designed to account for the turn on condition rather than the steady state operation.  This means that the linear supply is grossly oversized for the most part of the time.  Further, this linear supply is rather large, heavy, and costly.  Some audiophiles look at this and say, "yea, Apple cheaped-out;" but, it is really more a matter of pragmatics than anything else.  In fact, once understood, such a linear supply has some detriments, being designed for turn on rather than steady state; but, I'm getting a bit ahead of myself...

Second, the Purple Flare power cord is a pretty low capacitance design.  The Nordost website lists the capacitance of the Purple Flare at 10.0 pF/foot.  The inductance is 0.155uH/foot making the characteristic impedance about 125 ohms, once on runs the calculation.  I found this particularly interesting.

Going back to the power cord shoot out, knowing what i knew about some of the cables contained therein, and having measured some others, and trying my hand at building a few myself, I discovered a trend.  Generally speaking, there was a preference for a lower capacitance power cord on the mini - not in every instance; but, generally.  The twin lead Molex cord that comes with it is certainly a fairly low capacitance design.  Now, I was onto something.  I had a figure of merit, if you will.

Now, Robert and I really had something to chew on.  But, Robert said, "yea, I still don't care for the stranded conductors....and, the dielectric materials are effecting the results.  Let me try something, I think I can do better."

Enter the Alethias C7

A few weeks later, I held the Alethias C7 in my hands, examined it, and quickly installed it in my reference system.

The Ridge Street Audio Designs Alethias C7 is a tour de force in materials and craftsmanship executed by a seasoned cable designer and artisan.  Specifically, Robert makes use of a Furutech F-11(G) plug and the new, namesake, Furutech C7 connector.  The conductors are proprietary RSAD silver foil, cryogenically treated, and hand prepared in-house using specially developed cleaning and polishing processes.  For those in the know, this is course de rigueur at RSAD.

If I might digress for a moment, there have been two instances in my 30 or so years in audio when my system has been cabled completely with silver.  One that was a disaster and another sublime.  The first was at the behest of Herb Reichert, early on, when Audio Note first came ashore in the US.  The second was, and is now, with RSAD.   To me, Robert's cables are the only silver cables that exhibit benefits typically associated with silver without any of the commonly associated detriments.  I believe this is partially due to the aforementioned processing.

The exact geometric arrangement of the conductors I do not know.  Nor do I know the dielectric materials used.  I do know that Robert shot for a low capacitance design and the outer protective sheathing appears to be some sort of minimalist Techflex material.  I'm told that's intentional.  Robert also tells me that the Alethias C7 is a bit of a bear to build and I do know that he uses his own specially developed tooling to do so.  Similarly, and like all RSAD cables, the Alethias C7 is signal conditioned, once built, prior to shipment.

But enough of the sundry physical, mechanical and electrical details - what does the Alethias C7 sound like?

The Sound of the Alethias C7

In a word, the Alethias C7 is..., well: revolutionary and the Aelthias C7 redefines what is possible from the unibody Mac mini.

With all the things I've tried, the breadth of which might be denote as the letter X; surprisingly, at least to me, the Alethias C7 betters the best of that lot by easily an order of magnitude - that is to say, greater than 10X.  In fact, I don't know that I've ever heard a power cord on any one component make this much of a difference.  Certainly, the Alethias C7 is on the order of a power cord change on an amplifier.  Moreover, one really doesn't know just how wrong some other cords are until one has the opportunity to compare them to the Alethias C7.

Although Robert targeted low capacitance and I haven't measured and characterized the Alethias C7 out of respect, there's clearly more at work here than just locating and using a cable with a particular capacitance per foot and a specified characteristic impedance.  I'll even be so bold as to say that if you think you're going to achieve what the Alethias C7 does doing that, you're sadly mistaken.  It simply will not happen.

Therefore, I believe Robert is right, in that the type of conductors and dielectric materials play a substantial role in the sound of these power cords used on the unibody mini.  Were that not the case, the huge sonic difference between the Nordost Purple Flare and the Alethias C7 would not exist.

I've spent quite a bit of time with the Alethias C7 in the reference system here at Ultra Fi over the last several weeks and I find the virtues of the C7 to apply across all of the material I've played; but, here's my listening recollections for a scant half dozen songs used for comparisons.  They are all excellent recordings as well.

She's Got You, Jukebox - Cat Power

The seminally cool cover of the Patsy Cline classic and, probably, about the only one I can stand to listen to.  It has that way cool - we're playin' in the roller rink, tryin' to make a go of it, sound to it too. 

This is the cymbal track in the lot.  If the cymbals aren't portrayed correctly, you'll know about it with this recording.  The Alethias C7 nails the cymbals both in terms of upper extension and content.  In additional to being in the correct spacial relationship with each other, each cymbal is tonally distinct and sized appropriately.  Moreover, each stroke against each cymbal has the appropriate character.  I've had no other cord do this - though some cords, e.g., the Purple Flare, did get them in the right location albeit with squashed front to back layering.

This recording is also good for judging female vocal.  Again, the Alethias C7 betters the lot.  Cat Power is sized appropriately relative the drum kit and her voice doesn't jump out and blare at you like with some other cords, nor is she standing on your lap or the size of the Jolly Green Giant.  Robert tells me this is the dielectrics at play. 

Sarasate: Zigeunerweisen, Uncommom Ritual - Edgar Meyer with Bella Fleck and Mike Marshall

Continuing with differences in the portrayal of spatial aspects in recordings with regard to power cords used on the unibody mini comes this recording containing a performance by Bella Fleck.  I really dig Bella Fleck and became aware of Fleck through my interest in bluegrass music.  When I saw this recording listing him as a player, I thought, hum...I'll check it out...

There's little bluegrass in this piece, save some scant phrases, amid what most would consider overall a classical piece; but, there's wonderful dynamic contrast in this classical-bluegrass fusion.  With the Alethias C7, Edgar Meyer's bass growls and howls at you from more than twenty feet behind my speakers, emerging from blackness that allows the echo in the recorded space to accompany the playing, only stopping suddenly, so that Fleck's banjo might take your breath away.

The other cables aren't even worth mentioning here - in terms of space, bass or dynamics.  Now that I write this, it occurs to me that, bass and dynamics is probably what the Aletias C7 does best; and although you know it when the C7 is in the system, one really doesn't think about it because it is just so - right!  

Be Nobody's Darlin' But Mine, Love, Weiser Sunrise - Foghorn Stringband

As there their website says, "Ass Kickin' Reneck Stringband Music" and you gotta love a logo that has a skull and two banjos for crossed bones too.  For me, Foghorn Stringband’s unique  genre is the punk rock equivalent of bluegrass.  Raw, in its intended form, straight from the porch...

In this particular recording, the harmony singers are separated with the Alethias C7 like with no other cord in the comparison.  They're just standing there - unique and distinct - grouped and panned right.  And, you can almost tell which teeth in particular Caleb Klauder is missing when he sings - panned left.  Unreal, not to mention that the intelligibility of lyrics with the C7 is effortless whereas with the other cords, it is, at best, a struggle comparatively.

Cowgirl In The Sand, Live at Massey Hall 1971 - Neil Young

Awesome live recording.  The crowd intro is real with the Alethias C7.  With other cords, the applause is splashy and fake.

Neil's body (voice) and his guitar take on a relationship with the C7 that is not achieved with other cords.  They're just realistic - not disproportionate and/or changing in relationship throughout the song.

Big River, Bootleg, Volume 2: From Memphis to Hollywood - Johnny Cash

Ok, this recording could be a bit of stretch; but, it is simply miked and there's some really neat studio chatter in the front end of the piece.  Makes for a measure of depth though.  And, is this regard, the Alethias C7 is the King of the power cord jungle.

Plus, I like Johnny Cash...

'Round Midnight, In Walked Thelonious - Walter Davis, Jr.

This is the piano piece that some people just seem to require in order for a review to be complete.  So, here it is.  However, the reason that I put it here is due to some phasey imaging stuff that some cords just don't do correctly.  What I'm referring to is that, believe it or not, so many cords on the unibody mini flip to image of the piano from left to right.  That is to say, for example, that instead of the keyboard being on the left - the keyboard is on the right! Is this more accurate!? ‘...that instead of the keyboard’s lower register being stage left - that register sounds more stage right!’

The Alethias C7 gets the keyboard’s registers correct as a cohesive stage left to right spread and also portrays a unique perspective that allows the listener to have a sense of the length of each string as they vibrate, the later being unlike any other cord I've heard on the unibody mini.


Hopefully, this review will provide some guidance in selecting a power cord for the computer in your system.  Moreover, and in addition, hopefully it has shed some light on the process engaged in by one Robert Schult in developing the extraordinary Alethias C7 power cord.  But, most of all, hopefully this review will compel you to investigate, try, and explore the Alethias C7 thereby causing you to enjoy your music even more, much as I have with the Alethias C7 in my system.
power cord
there is c5 and c13 etc power cords and ac power cord,the power supply cord standard is iec 60320
Larry, thanks for your time and thoroughness to be helpful to the audio enthusiast community. Aside from your impressions of RSAD's Alethias!! C-7 AC cord for the Mac Mini, it's nice to see some other of your ideas and expereince to help get the most out of computer audio. Done right, computer audio really has matured as a high end system source and I trust it will only get better.

Since you didn't mention it, I will; If y'all are not aware, you can go to Ultra Fi's site @ On the left side, forth tab down is Larry's free 'Optimization Guide for Apple OS X'. Good stuff there that will help wring the most out of your Mac Mini. ;)

Cnstrongpower; this is really inappropriate for you to post here like this but, rather than ask the moderators to take you posts down here (which I'm sure they'd oblige...), I'll help promote you. Folks...for high fidelity audio reproduction, this is an excellent place to buy crap! While, unfortunately, RSAD's AC cords aren't inexpensive, this stuff's really cheap! If you've already spent $1-$15 for that music you wanted and have another couple bucks to spend, you could go to Strong Power's site and go nuts! :)

Agree with Robert on Larry's MAC OS optimization guide. I have used the tips in there on my Mac ook with good results.
I own a Poeima!!! digital coax and it's fantastic. I'm listening to it right now (Esperanza Spalding through lossless Ipod/ Wadia 170i into a Cary preamp). Robert knows what he's doing and his products are first-class.

This thread intrigues me because, as a home theater enthusiast, I'd be intrigued by the C7 as a cord into an HD DirecTV box. Is this a suitable application for the C7? Would it be worth it?
Hey Jan.

Nice to see you check in here.

Given my design approach to AC cords, I suspect the Alethias!! C-7 would offer an improvement but I've not really played in the home theater arena so I can't speak from experience and say for sure.

I have an idea how we can find out with no risk on your or my end. If you wanna pop me an email, I'll post you what I'm thinking....

Hey Jan.

Nice to see you check in here.

Given my design approach to AC cords, I suspect the Alethias!! C-7 would offer an improvement but I've not really played in the home theater arena so I can't speak from experience and say for sure.

I have an idea how we can find out with no risk on your or my end. If you wanna pop me an email, I'll post you what I'm thinking....