Are my CAT5 and router my weak link?

Kijanki - Your expertise in this area far exceeds my own. There may be good technical reasons to doubt that an ethernet cable can affect sound quality. Nevertheless, the effect I heard when I replaced an unshielded Cat 5 with a shielded Cat 6 was, from my point of view, too obvious to be attributed to placebo.

When a listener reports an experience that challenges an accepted explanation, it raises the question of the reliability of the listener. But it also raises the question of the reliability of the explanation.

Bryon

Using wireless LAN connection (Wifi) provides the best solution for physically isolating sensitive audio playback gear from potentially noisy computer gear as an insurance policy for best results. I would recommend everyone use this approach to connect their computer gear to their stereos and rest easy at night.

Bryon, Your case might be different. Perhaps Ethernet cable was in close proximity to analog wiring (interconnect or speaker) or I'm just plain wrong about it (I was wrong once in 1960). Audio is not exact science and I'm just trying to understand. Maybe balanced drivers are never exactly symmetrical and there is some high frequency component. It is possible that computer you used produced high frequency common mode noise. I hope Al will help with this.

Mapman, I Agree 100%. Not only that computers are noisy but also can and should serve its main function and therefore its location might be remote (mine is across the room). I use my computer during music playback because I know that it cannot change timing on the DAC side. For the same reason I use free Itunes, cheap computer, not a lot of memory, standard external hard disk etc. SIMPLICITY.

Hi Kijanki,

Bryon's situation is indeed different in several significant ways. One being that there is no wireless link between the cable in question and the system. However, following conversion of the ethernet data to S/PDIF, which is performed by a Sonos, the S/PDIF data goes through a high quality re-clocker, that also provides galvanic isolation, before it is input to the processor in which D/A conversion is performed.

I am in general agreement with all of the technical comments in your posts above, except that I would emphasize that matters of degree are involved. And the matters of degree have no clearly definable threshold separating what may be significant from what is insignificant. For instance, concerning your comment that:

This noise (whatever the source is) has to be strong and at least 30MHz to make effective (1/10 wave) receiving antenna of typical 1m interconnect.

While the 1/10th wavelength criterion is a reasonable guideline to use in many contexts, I would be hesitant to declare that in the context of an audio system an antenna that is less than 1/10th of a wavelength will be sufficiently INEFFECTIVE to reduce noise pickup to insignificance. Especially when sub-nanosecond jitter effects are presumably significant at the point where D/A conversion is performed. And given also that low-level RF may significantly affect the performance of analog circuitry. There is yet another thread that has recently appeared about someone hearing radio stations while listening to a phono source!.

Also, in addition to the possible antenna effects of interconnects and speaker cables (with RFI picked up by speaker cables perhaps becoming audibly significant as a result of entering amplifier feedback loops), I would not rule out the possibility that RFI picked up in AC power wiring may find its way to circuit points in the components where it could have audible consequences.

Concerning the 1/10th wavelength guideline specifically, I'll mention that some of my antique AM radios, that are designed to work with external antennas and do not include built-in antennas, will receive non-local stations on even the lower part of the AM band, with good quality, using a piece of plain hookup wire just a few feet long as an antenna. In those cases the antenna is well under 1/100th of a wavelength. And some of those radios, that do not have well-shielded RF and IF sections, can pick up those stations with no antenna connected at all.

Concerning the RFI reduction resulting from twisting of the conductors carrying balanced signal pairs, while obviously that reduction will be very substantial, it too is a matter of degree, and will not be perfect. How imperfect will it be, at each of the many frequencies that may be involved, and how much imperfection has to be present before there may be audible consequences? Obviously I have no idea. But my point is simply that if the OP's ethernet cable is located in relative proximity to the audio system, the possibility that changing the cable to a shielded type could make a difference for the better does not seem to me to be beyond the bounds of plausibility.

Best regards,
-- Al

Al, Thank you. I often tend to think in absolute terms while boundaries in reality are not that sharp. Tubeking sugested that shielding might compromise twist density making it worse instead of better. It is easy enough to compare since Ethernet cables are not expensive. I would use shortest possible cable as far as possible (since field drops rapidly (inverse square) with the distance. I would also avoid setting router at full power in close proximity if there is no need for that (no dropouts).

Do shielded cables require special connectors? I thought that plug has 8 pins (4 twisted pairs) with no room for the ground. Ground would have to somehow clip to chassis.