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
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.