Are my CAT5 and router my weak link?

In my own setup, I use an Ethernet Opto-Isolator that sits between the ethernet cable that feeds my "sterile" PC and the router that the cable connects to.

This device stops any electrical noise from traveling thru the copper conductors of the ethernet cable before it gets to my music server. Same concept as installing a dedicated circuit for your audio equipment, but for the LAN connection.

All the cheapo routers, NAS drives, ethernet printers..etc found in the home environment have no need to perform their function in a silent manner nor where they designed to do so. If you start to add up just the Wall Wart switching power supplies alone in the path between your PC and your DAC you begin to see an ugly picture form. Certainly the PC needs no additional help when it comes to generating noise so I feel anything you can do to help isolate it from the rest of this crud is a bonus.

Granted, the number of configuration choices one could pick from to setup a music server are fairly broad so some may be more affected by said noise than others and if you have done nothing at the PC level to help lower its own noise than all of the above may not matter anyway.

In my own setup I use a low power ALIX computer running Voyage Linux which only requires about 12 watts of power to perform its duties. I feed the ALIX computer power via an adjustable laboratory grade linear DC power supply. In my case this Opto-Isolator makes sense as the music server is already pretty clean from noise so any additional filtering is a plus. My DAC is also optically isolated from the Alix computer over its USB port Input (Ayre QB9).

To SGR,

I purchased my Opto-Isolator from Black Box (linked below). I am using the 100MB unit as it offers more than enough bandwidth for audio purposes but they do sell GB ones also.

http://www.blackbox.com/Store/Detail.aspx/Ethernet-Data-Isolator-10BASE-T-100BASE-TX/SP426A

By using one of these Isolators you are eliminating any noise from propagating beyond the point of its location. There is no need to rewire your LAN again.

For our purposes (Audio) CAT5 is more than sufficient in this configuration (with Isolator) because at the end of the day these other cables are offering nothing more than additional shielding from interference. The ones and zeros could care less about this interference unless its so severe as to cause them to no longer be the same ones and zeros at which point you obviously have other issues to worry about.

I have done some fairly through testing of this unit prior to using it in my own setup and found no difference in data transfer rates or ping times with the device Inline/Not Inline. I also conducted CRC Checksum testing of data that passed thru the Isolator verses the same data that was copied without the Isolator and found it was 100% the same in both cases.

Hello Al, thanks for your response. The only detail I could dig up about this devices ability to reject current leakage across the optical isolation barrier was found in an article pertaining to the European Medical Device Directive (EN6060-1) which this product is said to comply with.

If your real bored and feel like reading it I have linked to the document below which talks about the allowable current leakage given a certain air gap distance which I can only assume this device complies with. From what I saw, the European standard allows for .5mA worth of Earth leakage & a .1mA enclosure leakage under normal conditions. Double that during an "Event".

Article can be found here:
http://www.newark.com/pdfs/techarticles/xpPower/MedicalPowerSupplies.pdf

SGR, In terms of the SQ differences I heard before and after the installation of the device I'm afraid that in my setup I heard no change under normal day to day listening.

I think I could here a slight difference under critical listening sessions (more air around the performers within the soundstage) but certainly not enough to convince any DBT subject.

Please keep in mind that in my setup previously described I have already gone to great lengths to minimize the propagation of noise via the LAN cables as much as possible even before the purchase of this device. In someone else's system the SQ differences may be far greater than my own if they haven't taken all the same precautions. One example of these precautions would be that I maintain at least a 3ft gap of separation between all of my various networking equipment and non of which share the same electrical outlet. This alone helps with any one noisy device from polluting the other which could ultimately compound the amount noise radiating thru or traversing down the Ethernet conductors toward your audio system.