PC Challenge Test Results


As a result of the "PC challenge" thread, I've now had a chance to put a high-end aftermarket PC to the test in my system. First, sincere thanks go to Albert Porter for helping to set up the test, and especially to Jim of Purist Audio for his hospitality in loaning me a PC. Jim also was quite gracious about how long the testing took.

Jim sent me one of his Dominus power cords. This PC clearly uses very, very high quality components and the level of construction appears outstanding; this is certainly a PC at the highest level. I'd guess that you could jump-start a car with this wire! I don't know if this cord costs $50 or $5000 (bet it's closer to the latter), nor did I want to, to avoid possibly influencing the test.

My initial listening took two approaches. After having powering-up the cable for 72 hours as was recommended, I listening in a very relaxed manner, without trying to identify any specific differences. Did my system seem more or less enjoyable than I remember? The answer is yes, it did seem more enjoyable; there seemed to be less "stuff" getting in the way of the music perhaps, a clear although not huge difference, and there also seemed more of a foundation to the music. The question then became whether or not I could pick out specific differences? Again, compared to my recollection of the system sound the answer is yes. While the changes were relatively subtle there appeared to be more and better bass (slightly deeper and more defined, more of a visceral impact) and the vocals somewhat more natural - less "in your face", perhaps. The lack of bass depth is an inherent shortcoming of my system, but the vocals had never stood out as a problem area before. Overall, the sound seemed more transparent, quite a feat given I think that's one of the primary strengths of my system. Bottom line for this part of the evaluation: the Purist PC definitely added to the system, although subtly.

Now, that being said there I had some very strong concerns on the above given that this was a sighted evaluation. It could very well have been that I expected and was listening for exactly those effects (not the vocals, though - that surprised me), or that my audio memory of the previous setup was flawed. I wanted to try some blind evaluations as a test. I have no ABX-type of setup, so was unable to conduct any tests that I'd consider truly scientific, but tried something that was informative nonetheless. With the help of my brother, we did some rapid-switch testing: he flipped a coin and either switched between the Purist PC and stock, or not. I typically listened for 2-3 minutes to the Purist before the switch/not-switch and an equivalent time after before deciding, and got 7 right out of 12 trials; we then tried it with the stock cable first and I got 5 out of 8. I've not yet hauled out my old statistics textbooks, but am pretty sure that this would fail most reasonable hypothesis (say, "there are sufficient differences (95% confidence level) between these PCs that I can identify them correctly 80% of the time).

So what does this mean? Nothing beyond that it appears, in my system, that I probably cannot discern any purely audible differences between my stock cord and the Purist. Any broader conclusion is unsupportable from my testing alone, although I do suspect that equivalent results would hold for the population at large. But - and this is a big but (no jokes, please!) - before the blind testing I did perceive an improvement in my system; for many, this is sufficient and they may gain a real benefit from aftermarket PCs. In my case, though, I'm better off adding a sub than investing in aftermarket PCs.

Cheers,
JHunter
jhunter
Hard to tell. There are so many variables. I was able to tell the difference between two different after market PCs and was not doing any kind of test. Did not even cross my mind there would be a difference. I had picked up a PC and it was not quite long enough. I had another longer PC being used another place that was long enough for both places. So I swapped them. I unexpectedly noticed a slight loss of bass and a higher noise floor where the longer cable was originally, when I turned the component back on with the shorter cable. So I put the longer one back on, and went back to the store and exchanged for the same longer PC.
For the thousands in attendance and the thousands watching from around the world, Ladies and Gentlemen, LET'S GET READY TO RUMBLE!!
JHunter: Did you try the PC on a source component or an amp? Hopefully both.
Here's the system:

Transport: Pioneer 525 DVD
DAC: MSB LinkDac III
Integrated amp: Plinius 8150
Speakers: Dunlavy SM-1
Cables: low-end XLO coax cable (DVD -> DAC); Nordost Silver Wind (DAC -> amp; very low capacitance and looks cool, although it's buried in the system); XLO ???? low-guage speaker cable (got cheap, looks cool and were heavy enough for my old Maggies).

I used the power cord on the Plinius as Albert recommended, plus it gave me 2 component's worth of change equivalent(pre- and power) for most systems.
Thanks for taking the time and effort to carry out and report on your project. The results are not surprising and I suspect they would not be that different for any other number of other components (cables, amplifiers, isolation devices, CD transports) where the differences are, for the most part, truly subtle. Another factor to consider is not whether you can hear a difference, but whether the differences you hear are musically important. For instance, under most circumstances a lower noise floor is less important than increased harmonic coherence.

I suggest the following for a test setup: secure 2 identical test CDs and also secure 2 identical CD players. Then using identical cables feed the CD players into separate inputs of a preamp. The power cords for the CD players would be the variable and you could switch easily using the preamp input control.
Jhunter. Our thanks to you for investing the time to make this comparison and post results for all to see here at Audiogon. You have openly and honestly presented both sides of your test, and for that, my sincere thanks.

My primary concern over the blind portion of your test concerns the mechanics of frequently changing the test cords and the assistant's handling of them.

When a Purist Dominus power cord is disturbed it requires as much as three days to recover, with 20 minutes being the minimum. One last test you might make before shipping it off would be to first listen extensively to the Purist with music you are familiar with. When you are ready, walk over to the Purist and pick it up a few inches, mash it slightly with your fingers (or bend it) and let it fall back to the floor.

Go back to your original listening position and enjoy the music again. You will hear a distinct change for the worse. As you continue to listen, the sound will slowly return to the level of performance you enjoyed before the disturbance.

A great deal of your confusion with the blind portion of the test may be clarified by this last experiment. It would be interesting to see if you can identify the changes from the bend/drop test and factor them into the final results.

You were probably unaware of this variable. Essentially, you were trying to identify three sounds (or more) instead of two. The original or stock cord, the Purist cord working at it's best, and the Purist cord in various states of recovery from swapping during the blind test. This variation would make it difficult to arrive at any confident result, especially if you did not know why it was happening. Even when the same bend/drop test are performed in sighted listening sessions where the listeners are aware of the reason for the change, it is surprising to hear the results.
Nice system JHunter and also thanks for taking the Pepsi challenge. I also like HWY's test suggestion. The cords and inputs could later be switched on the players and the tests ran through again to see if the same results come up. I am certain that you must be tired of it all by now though, as there's nothing like getting back to listening to the music, instead of the gear.
Thanks, Jhunter, for taking the time to share your experiences with us. You were honest in describing what you heard, and that is a great service to this community. I share Albert's thoughts about the possible unintended consequences of the attempt to do some blind testing by swapping the cables in and out. I also experience the phenomenon that moving my cables requires a re-settling period before the sound gets back to where it was.
JHunter, I think the above posts express it well. Thanks for taking the time to run the test and providing your unbiased results.
Thank-you Jhunter for the time and willingness to test the cable. As expected we solved nothing, only raised more questions. I agree with Albert that the second part of the test has potential for error, but I'm happy you made the effort.

I think the true test will be in time. Will you decide your missing "something" when you send back the cords, or will you remain content with the system as it was.

I wish we could have resolved this issue, in that it becomes very old and tiring, but so far we have not. Thanks again for the open mind. (that's really all I'm looking for) J.D.
Like all the others have stated, thanks for posting your HONEST results. All of our "debates" here have NOT been in vain if we help open minds and explore new avenues that some folks otherwise might have left alone. Once again, thanks for sharing your experience with us. Sean
>
As the others, I thank you for your sincerity and honesty. Please don't take this personally, but:

1. I don't know many people with requisite experience in listening who also don't know that Purist cables, and particulary the Dominus line, are very expensive, relatively speaking.

2. You should be able to hear a difference on the Plinius in terms of bass registers, but, to be frank, your system, although well thought out, is not of the caliber to benefit from a cable like the Dominus PC or the like (eg. NBS Statement I on Pre's/CD, Electraglide FatBoy on amps, etc.)in terms of harmonic and spatial effect.

3. Most people who would be interested in a Dominus-level PC already know, as Porter alludes, that NBS, Purist et al are very suceptible to movement. Whether you ascribe to the theory that the dialectric needs to re-form, or whatever, the fact is that, once moved, the cable needs at minimum 48hrs play-time to "re-settle". Absent that time - and I submit that its more like 100 hrs to get everything back - the cable will sound brittle on breath transients, lean on harmonics and phasey.

Well-intentioned and well written. But again, with respect, I believe that the experiment - if it truly wishes to aspire to the rigors of ratio-empiric method - must be examined in light of these deficient variables. But, don't stop, keep going. The essence of empiric method is trial and error, and those erros many times occur in our original assumptions that underlie our experiments.

As Sean says, your passion is what is most admirable. Don't stop, keep going.
Great experiment, Jhunter! Re, remarks regarding "cable disturbing" etc. Just came across a professional catalogue on equipment & installations destined to electricians issued by Legrand, a french electrical equipment multinational.

Samples of advice for "...when installing cabling... particularly conducting inconsistent loads, or powering inconsistent circuits especially ones with variations in the frequencies carried (audio, voice, voice & data)..."
*ensure that cables running in parallel are physically 15cm apart regardless of insulation quality
*do not bend the cables abruptly (energy loss in low voltage situations!). Rather, create space for large diametre turns and hide the cables appropriately.
*If you encounter temporary cable overlapping, ensure 90 degrees cross at the cables meeting point.
*At very low voltages with high frequency variation, measure losses before final installation. Use SSTP cables or any other balanced conductor specially designed for such applications.
*Ensure all connections are according to norm and connectors used... withstand weather and pollution conditions. If in doubt, or measured losses are high, try direct connection with end appliance without external connector.
*For dependable readings, allow the installation to reach an electrical "balance situation". Make sure you connect a proxy load at reception end asap if the installation is uni-directional. Allow your system to repose at least 1 hr. with a load while you continue other work. Readings will not be reliable unless the installation reaches this balance! Do not allow variations of more than 5% in readings within the same 30 mins!
*Measure airbound losses -- if exposed cables do not give steady reading, switch the meter to "save" and physically move the exposed part of the cables. Differences of more than 7% may mean re-installation! Please consult our technical dep'timmediately before removing the installation!

All I'm saying after this long blurb (thanks for the hospitality Jhunter & all) is: industrial application are doing some of the things we heatedly debate!
For me, voodoo because I can hardly understand the intro to a physics handbook let alone install industrial norm cabling. For others, all in a day's work!

I mean, there must be *some* resident EEs at Legrand, ABB, motorola, etc, surely. What if EEs wrote this stuff?
How come they don't post here?
Jhunter; I too enjoyed reading your thread and the ensuing posts. Thanks. Craig
I'll echo everyone else's aproval.
Regarding cable movement affecting the test...

"When you are ready, walk over to the Purist and pick it up a few inches, mash it slightly with your fingers (or bend it) and let it fall back to the floor."

I think it would be best to also keep the listener's position, heart rate, etc. constant and have an assistant pinch the cord. I would also like to know if someone could successfuly indicate that a power cord is beinging pinched if they were blindfolded.
Maybe Bruce should do the pinching. He is, after all, Italian.
In response to Asa’s comments

1. I don't know many people with requisite experience in listening who also don't know that Purist cables, and particulary the Dominus line, are very expensive, relatively speaking.

I’m not sure what the point of this is, other than perhaps to imply that I don’t have a background adequate to hear what the Purist PC did for my system. Just because I don’t know the price of a particular piece of equipment (and I did say that it seemed clear that the Dominus was pricey; I just looked it up and found it lists for $1500), please don’t assume that I do not have the “requisite” listening experience, whatever that is. Perhaps I’ve not spent as much time listening to equipment as others, but have a pretty reasonable background listening to real, live music: 30+ years as a relatively decent amateur musician (well, maybe 20 years for the “decent” part, and some may dispute that!), hearing live, unamplified instruments 1-2+ per week on average.

2. You should be able to hear a difference on the Plinius in terms of bass registers, but, to be frank, your system, although well thought out, is not of the caliber to benefit from a cable like the Dominus PC or the like (eg. NBS Statement I on Pre's/CD, Electraglide FatBoy on amps, etc.)in terms of harmonic and spatial effect.

I have to admit that with a system running ~$6k or so (list), I haven’t spent much time looking to buy power cords at $1500 apiece. Anyone who would spend an equivalent amount on power cords as components is, to be very kind, showing questionable judgment if they feel that is a reasonable approach to upgrading their system. As I said, my personal $1500 upgrade would be a subwoofer, something that is unquestionably audible.

I was not shopping for a Dominus-level PC; it was arranged by Albert Porter, and very generously lent by Paul at Purist. While my system is not the absolute, it is really quite revealing and keep in mind that they chose the Purist as one that, knowing my set up, they felt would be a very audible step up from the stock cord.

3. Most people who would be interested in a Dominus-level PC already know, as Porter alludes, that NBS, Purist et al are very suceptible to movement. Whether you ascribe to the theory that the dialectric needs to re-form, or whatever, the fact is that, once moved, the cable needs at minimum 48hrs play-time to "re-settle". Absent that time - and I submit that its more like 100 hrs to get everything back - the cable will sound brittle on breath transients, lean on harmonics and phasey.

If you believe that the movement has an effect, isn’t it a coincidence too amazing to accept that movement does not leave the Dominus audibly better (if that is how it started), make it audibly worse or even just plain audibly different from the stock cord, but somehow makes the two PCs statistically indistinguishable within the limits of my test? That is, the breath transient brittleness, harmonic leanness and phasey-ness are induced in such a way as to precisely match the stock power cord?

Well-intentioned and well written. But again, with respect, I believe that the experiment - if it truly wishes to aspire to the rigors of ratio-empiric method - must be examined in light of these deficient variables. But, don't stop, keep going. The essence of empiric method is trial and error, and those erros many times occur in our original assumptions that underlie our experiments.

Thanks. I did go into this test with an open mind (never can tell what you’re going to learn), although my technical background led me to issue the “Power Cord Challenge” in the first place. I’m fairly well grounded in the scientific method, which is why I put the caveats regarding any broad validity or interpretation of my tests. I am satisfied that the results have meaning within my originally stated limitations, however,. Enough serious testing, though, for a while I’d rather just enjoy some music!
Sorry about the confusing responce to Asa - I'd noted who wrote what but that somehow got lost when posting. FYI, the paragraphs immediately following "1.", "2." and "3." are Asa's, as is the paragraph beginning "Well-intentioned . . .". All others are my response.

JHunter
Any such experiment with audio gear is personal and contextual. In the end Jhunter decided his next dollars would go on a sub rather than PCs. That is the significant outcome of the experiment brothers and sisters - for Jhunter in his room with his current system. And thanks for sharing it Jhunter.

Others here find PCs to be more vital, and I wouldn't dream of swapping mine for a sub. Some here just don't want to know about PCs, for whatever reason. Jhunter's experiment proves nothing, but who cares - if it causes a few others to at least try PCs with an open mind, then great.
Thank you, JHunter, a well-measured response. As Redkiwi states, knowledge is contextual. I would also add that it is also the mind that hears music, not the ears, and in this context, knowledge is state-specific. We will have to agree to disagree, but thank you for addressing the content of my points. I look forward to your next foray.
Every posting on PC generates tremendous response. You would believe that this is all our hobby is about. Now we learned more variables. Pinching cords? Is this P(olitically) C(orrect)? What if the cord is less than 18(gauge). I suspect it is not even legal. But seriously folks, if power cords or similar tweeks are so important how come are used so inconsistently by professionals? I am referring to the recent NYC show and similar venues. You would expect the manufacturers to try to improve the final sound as much as they can. On the other hand, you see in some cases using the Michael Green Power company mains treatment which Home Theater magazine came out and said that it had a negative effect on a pure audio system. So, I think that business alliances play major role. And finally if every time you disturb a PC you have to wait up to 100 hrs to restabilize, one lifetime is not enough to conduct a definite comparative test. (Another good reason to make cloning legal).
Pefstratiou. To address the serious part of your post, there are lots of professionals that do use high end interconnect, speaker, and AC power cables. In fact, I do not know of a single high end manufacturer that does not use one or another of the audiophile brands. The opinions as to which of these cable is best, varies as do the opinions of the posters here at Audiogon.

Audiophile cables are commonly used in music production as well. Most obvious are Audioquest, Analogue Productions, Classic Records, Cardas, Chesky, First Impressions Music, Groove Note and DCC.

Even the new Delos classical masters are auditioned for edit, using Purist Audio cables. I know this for a fact, as I listened two weeks ago to this system, with a yet to be released master as the source.

Regarding difficulty in maintaining accurate results in your system when the cables are moved. Many, if not all high end cables are effected by this phenomenon. Purist is certainly among the most susceptible. This makes testing all the more difficult, with long term listening being the only cure for the ill. Not surprising, Redkiwi and I have beaten this horse many times, and is one of our primary objections to the ABX testing method.
NBS is another cable company that produces its own recordings: fine microphones, preamps, hall acoustics, recording media, AND excellent cables. The booklet for NBS Listen Records cat. 002 even says "NBS cables are the key to the clarity of this special recording."
Gee, NBS praising NBS cables?? Then they MUST be good! ;-)
Jhunter: You are so transparent (if you want to audition the NBS PC's next, just give them a call:-).
Jhunter, I know what you mean. I cannot tell if the sentence I quoted is from the recording engineer for the CD ("Russ Borad") or someone from NBS's promotion department--probably the latter. The recording itself is very simple: two acoustic guitars each on one side of a female vocalist singing (sometimes pretentious) love songs (in short, a sound-stage reminiscent of a Fado CD). The text for NBS Listen Records cat. 003 has the phrase "first class NBS microphone cables" in it, if anyone wants another example of self-promotion. I mentioned all this only to lengthen Albert Porter's list of professionals using high quality cables for their work.
Nobody tell Jhunter the price of the NBS PC's otherwise this will influence his test;-)! Actually, I think they are slightly less susceptible to movement anomalies than the PAD Dominus, so it might be suited to his test methods. Just make sure to test them out on your CD player rather than your amp: I want to see better results this time.
Hi Jhunter, job well done and for me I do mean job. If you can keep the PC for another week or two try leaving it in for a week and get used to the sound of your system again. Then replace it with the Stock PC. Thanks to your challenge I am finding out that trading the PC in and out is not the proper way to evaluate IMO. I have to turn off my tube amp and CDP. It takes about 20 minutes for the system to sound decent again. I have convinced myself this is not the way to evaluate PCs or anything else. You will set yourself up for failure or may fail to realize the potential of this PC or whatever you are evaluating. IMO swapping PC in and out is almost usless, at least for me it has been. I am barely above 50% and I'm the one doing the swapping. I don't know if it is warm up, Cable disturbance, or what. I am finding this true with IC and speaker cable also. For whatever reasons the system sounds the way it should hours later.
If you are able to try this, I would be very interested in any feedback.
You are a good man Jhunter even though you made me do a lot of homework.
It is noticeable how much serious interest--VERY serious, involving lengthy tests and debate--in power cables has increased on audiogon over the past half year. Yet, look at the "2001 Recommended Components" of "Stereophile" and you will not even find a separate rubric for power cables: three cables are slipped into the "Power-Line Accessories" rubric, and none of them have been hotly discussed on audiogon. (No Purist Audio Dominus, no NBS Statement, no Shunyata, no Fat Boy, no Eel).
By the looks of this site, Stereophile would risk losing half their subscribers if they did tout PCs.