KSTR
Major Contributor
Hi everyone,
We all know the myriads of testimonials about cable sound obtained from sighted listening and completely uncontrolled conditions (level matching etc), which makes them basically moot. Then again, the sheer number of reports would statistically allow for at least a handful of setups where some form of cable sound actually did happen and could have been proven with the right means at hand.
Generally, I'd like to divide potential cable sound -- talking line level interconnects here as for now -- in two categories:
Category A, trivial cable sound: this is what comes from using a cable simply not up to the task, and/or from side effects not actually contributed by the cable itself, apart from its basic properties. Some examples would be:
We would only be interested in Category B here, the „intrinsic cable sound“ claims.
Attempts have already been made trying to verify cable sound in more controlled manners, like the required level-matched blind comparison, and occassionally some positive results may actually have been found. Alas, the setups usually were not prepared for a technical investigation, on-site and in-situ, as to what causes the differences, technically. More simply worded, it is a futile attempt to measure the cables under completely different conditions than those that applied during the blind tesing (assuming it created positive results). You might say when we are after intrinsic cable sound the circumstances should not matter much and the „characteristic“ of the cable should manifest in the lab, and of course this should be true. Then again, when a BT yields positive results wrt to differences percieved this sort of guarantees -- within the limits of the statistical significance the test allows for -- that there must be actual differences in the signal and it would be very nice and insightful to peel out these difference in the actual music material that was used for the test.
Cable Blind Tests in real life, using people's actual HiFi rigs, are a complicated matter. But in this age and day of the internet, there is a way to remote the tests to a large group of participants by using loop-back recordings. While not exactly recreating the situation of a real cable change in one's system, chances are there that the captured differences can still be identified. Plus we have the great opportunity that the circumstances are extremely well defined and replicable and everything is in one hand, allowing for meaningful analysis as the setup for the recordings is exactly the same for the technical investigation and the recording for the blind testing.
So what I have in mind is the following:
Best, Klaus
We all know the myriads of testimonials about cable sound obtained from sighted listening and completely uncontrolled conditions (level matching etc), which makes them basically moot. Then again, the sheer number of reports would statistically allow for at least a handful of setups where some form of cable sound actually did happen and could have been proven with the right means at hand.
Generally, I'd like to divide potential cable sound -- talking line level interconnects here as for now -- in two categories:
Category A, trivial cable sound: this is what comes from using a cable simply not up to the task, and/or from side effects not actually contributed by the cable itself, apart from its basic properties. Some examples would be:
- using a very long high capacitance cable on a very high impedance output (passive preamps and such).
- using long unbalanced cables, or ones with high shield resistance, or even unshielded „return wire“ types in setups with „ground loop“ problems. Same with cables that have open shield connection on one end.
- using badly shielded, or even unshielded cables in general picking up external electrical and magnetic fields, and notably in setups where the cable connects to devices that suffer from EMI problems (RF demodulation)
- ...
- silver conductors sound different than copper conductors
- high purity copper / silver conductors sound different than off-the-mill copper / silver
- single-strand (solid-core) conductors sound different than multi-strand
- plated conductors sound different than non-plated
- isolation materials matter (dielectrica)
- geometry details matter
- ...
We would only be interested in Category B here, the „intrinsic cable sound“ claims.
Attempts have already been made trying to verify cable sound in more controlled manners, like the required level-matched blind comparison, and occassionally some positive results may actually have been found. Alas, the setups usually were not prepared for a technical investigation, on-site and in-situ, as to what causes the differences, technically. More simply worded, it is a futile attempt to measure the cables under completely different conditions than those that applied during the blind tesing (assuming it created positive results). You might say when we are after intrinsic cable sound the circumstances should not matter much and the „characteristic“ of the cable should manifest in the lab, and of course this should be true. Then again, when a BT yields positive results wrt to differences percieved this sort of guarantees -- within the limits of the statistical significance the test allows for -- that there must be actual differences in the signal and it would be very nice and insightful to peel out these difference in the actual music material that was used for the test.
Cable Blind Tests in real life, using people's actual HiFi rigs, are a complicated matter. But in this age and day of the internet, there is a way to remote the tests to a large group of participants by using loop-back recordings. While not exactly recreating the situation of a real cable change in one's system, chances are there that the captured differences can still be identified. Plus we have the great opportunity that the circumstances are extremely well defined and replicable and everything is in one hand, allowing for meaningful analysis as the setup for the recordings is exactly the same for the technical investigation and the recording for the blind testing.
So what I have in mind is the following:
- I will make precision and well-documented loopback recordings with all the necessary care, using different cables (I have some „higher quality“ XLR and RCA interconnects here on loan for this, besides my bog-standard interconnects). The RME ADI-2 Pro, USB connected, is an obvious choice for a DAC-->cable-->ADC loop-back setup, for making the recordings, plus I actually happen to have two of those interfaces so that more „real-world“ scenarios than simple loop-back within a single device can be tested as well if that is deemed necessary for any sort of reason.
- Phase 1, Getting Familiar: I will offer the recordings for a sighted subjective comparison first, to establish some sort of baseline if people think they can hear some differences in the first place. Open discussion and sharing of impressions and hints what details to listen for are welcomed. This of course opens the door for priming (the first published testimonials, and any "reputation" of the person stating it, will subtly influence others in their subsequent sighted findings) but this is fully intentional. I want to recreate the normal end user situation as seen in the more subjectivist forums.
- Phase 2, Assertion: Once enough feedback has accumulated that at least some are certain to hear differences, the blind-testing phase proper will start, otherwise the specific test will be over and we have to start from new, using different test tracks, change some details of the setup and whatnot, of course it will be a limited amount of cycles. Preferred format for the blind testing is ABX log made with foobar2000 and associated ABX plugin but we might have other options, too. I'm aware that cheating is possible but lets take that aside for now. ABX'ing requires patience and training, so it would be best everyone gets familiar with it early on, right in Phase 1. Preferably, we will have several rounds of Phase 2, occassionally using hidden positive and negative controls to increase the robustness of any results.
- Phase 3, Investigation: If some evidence can be accumulated that in the specific setup used to make the recording there are perceived differences, we have layed the grounds to actually start an in-depth technical investigation to search for the differences in the signals that are deemed responsible for the changes. Otherwise, the test is over for obvious reasons, though it still could be worthwile to check the recordings. The technical investigation is basically simple, just look for differences in the signals, but actually the details can get quite complicated, and of course baseline stuff is required to establish limits of resolution and uncertainity, all the bells and whistles needed for a proper technical analysis. I have some years of experiences in this field, as will other have, so I am really confident that once cable differences are nailed down in blind-testing, one can find the dominant root cause.
Best, Klaus
