A-B testing of cables

Thanks for referencing the audioholics articles. I know it well and was about to list it myself. In it, they call the DBS system snake oil, and follow up with some scientific info as to why the DBS will make no difference. I see a couple of problems with their argument.

The main issue is simply this: If you read through the articles carefully, you'll see that not 1 of the skeptics so much as laid a finger on a DBS cable. How can anyone make a conclusive statement on the system without actually using it first to see if it works or not? Its silly. In order to claim science, you need to do something scientific. If they would have tried some of the AQ cables and didn't hear a difference, I can respect that. But they're not interested in the truth, they're more concerned about winning the argument.

The other major thing that stands out in the article, is that they're challenging AQ to send them some cables to demo. To me, that sounds like they are afraid that they may be wrong. I say this because if these people wanted to conduct a test of the DBS system, they could easily do so at any time. You don't need AQ to do that. DBS cables are sold in Best Buy. They can buy a pair, test them and then return the cables if they are not happy with the results. What could be easier? That's what most of us here do if we are considering new gear. We demo it. The skeptics can do it too, but they choose not to. I wonder why.

You lost me at the Y-cable....another misguided well meaning audiophile goes down the rabbit hole. Sadly, cables that cost a fortune can and do sound better....as always, the results are system dependent and thoroughly neutralized by pseudo-intellectual, financially challenged DIY types.

Perhaps a different test could be tried using both mono amps and speakers thus:
Hook up one channel of the preamp to one splitter, then send both signals to mono amps and then to speakers. Put the speakers next to each other. Result is a duplication of one channel, but using different interconnects (or speaker cables if desired, but not both at same time). One speaker could be connected to each output (i.e. Output 1 Left channel, and Output 2 Left channel) of the amp. Simple switching between the outputs of the amp at a moderate listening level could yield quick comparison versus turning off the amp, swapping wires and establishing the signal again.

The differences in order to be efficacious must be immediate, easily heard. If not, then either the cables have very similar design, or one's ears do not perceive the differences. That's not a judgment, just a conclusion.

I find that some listeners have a difficult time with any delay in comparison, and they cannot retain very well what they heard. This setup would eliminate a long pause and make it easier to hear the result in an instant. I do not find that some systems are less sensitive to cable changes, but I do find that some are less resolving. The OP's rig is plenty good for this test.

With this setup the OP and friends might hear some differences, with various cables. If they still cannot hear the differences, then they should simply pursue economical cables and be happy. :)

"With this setup the OP and friends might hear some differences, with various cables. If they still cannot hear the differences, then they should simply pursue economical cables and be happy. :)
Douglas_schroeder (System | Reviews | Threads | Answers | This Thread)"

Not necessarily. That test has some serious flaws. The first is the splitter itself. Depending on how well its made, it could rob the system of detail that would normally be there without the splitter. Also, since cables are system dependent, the splitter will match up differently with with each cable. Cable A may match up with the splitter "better" than cable B. And you'll have to double up on the runs because the splitter is in the way.

More importantly, though, testing a cable using this method won't allow allow you to hear any spacial information. To see how well a cable images, you need to be listening in stereo. Scale/image size, and how forward/distant the presentation is, can't be determined either.

FWIW, I agree in part with the preceding posts by Doug and ZD, and disagree in part.

I think that the criterion of immediate efficaciousness, which Doug has stated a number of times in the past as well as above, has a lot to be said for it. Especially in the context of cables, as well as tweaks of various kinds. Although at the same time I recognize that there can be subtle differences that may take a relatively long time to initially perceive, but once initially perceived can then be identified fairly readily in subsequent listening.

I agree with ZD that there are problems with a comparison that involves only one channel of information. In addition to the issues he cited, there is the fact that while differences may be noted in many cases in such a comparison, one's ability to reach a meaningful conclusion as to which of the items being compared is "better," or at least subjectively preferable, will be compromised by the missing information. And also by the altered placement of the speakers in the proposed test.

Regarding splitters, from a technical standpoint my expectation is that in the majority of cases the negative experiences people often report with them are not caused by the splitters per se, but rather by one or more of the following:

1)The fact that the component supplying the signal is driving two load impedances, rather than one. The combined impedance of the two loads will always be lower (more challenging) than either of the two individual impedances, and will usually be MUCH lower. (To calculate that, multiply the two impedances together, and divide that product by the sum of the two impedances. To assure that the combined impedance won't be too low to be suitable, that result should be at least 10 times greater than the highest output impedance the component supplying the signal has ***at any frequency***).

2)The fact that the component supplying the signal is driving two cables, especially in regard to their capacitances. (The combined capacitance of the cables equals the sum of their individual capacitances). The combined capacitance of BOTH cables will affect the signals seen by BOTH components that are being driven, as a result of the interaction between that total capacitance and the output impedance of the component supplying the signal. In other words, to cite a common application of a splitter, if one is used to split the output of a preamp so that it is routed to both a powered sub and the main power amp, the capacitance of the cable to the sub can affect the high frequency content of the signal seen by the main power amp just as much as the capacitance of the cable which connects to the main power amp. Or even more, if the cable to the sub is longer than the other cable and/or has higher capacitance per unit length.

3)The possibility that sonics may be affected by low frequency, high frequency, or even ultrasonic noise that may be introduced as a result of ground loop effects occurring between the three interconnected components, that might not occur if only two of them were connected.

Regards,
-- Al