Basic electrical questions.

12-09-08: Almarg
Can someone offer either a technical explanation, or at least some persuasive anecdotal evidence, to explain the claim that running multiple dedicated lines to the different components of a single system is beneficial.

12-10-08: Kirkus
I'm mostly with Al on this one. The paper that Jea48 refers to is interesting and has some valid information, but there are also some typos and mistakes . . . and I think that some of his conclusions are a little questionable.

12-10-08: Zargon
From an electical engineering perspective, separate dedicated circuits all connected to the same subpanel would all be in parallel with each other. This means that any spurious artifacts from a component fed back into its dedicated circuit would be superimposed on all other dedicated circuits. Other components power supplies would have to deal with these artifacts, e.g., filter them out. In this regard, this approach is not any better than a single dedicated circuit.

There is up to a hundred feet of wire in the walls, so the last 6 feet of power cord can’t possibly make any difference.

Answer: The PC is NOT the last 6 feet as stated in #1 and the local current and EM effects directly affect the sonic performance of the component. The power cord is not the last 6 feet, it is the first 6 feet from the perspective of the component. The further a noise source is from a component, the less of an impact it will have on the components power supply. The high-frequency noise sources that have the greatest impact on audio and video performance are the system components themselves -- which are usually all in close proximity of one another and all emit radiated fields of high-frequency noise. A well designed power cord can act as a noise-isolated extension of the primary winding of a component’s power supply and will help isolate the power supply from the fields of radiated RF and EM noise energy that is ever present in all electronics systems.

In my own system, I have installed an isolation transformer feeding the subpanel, with separate dedicated lines to each component. To address the issue above, I have put a second isolation transformer on the CD dedicated line to keep its digital hash from contaminating the other components.

This has proved very effective for me, as there is now no difference in the background noise level between the CD player while off, and the CD player playing while muted. If you are contemplating multiple dedicated lines off a single subpanel, I suggest you consider this approach.
12-10-08: Zargon

One point of interest here is what was said about the actual length of the ckts themselves. I read somewhere there is a formula for figuring out the db per feet in loss. I don’t recall it now, but I know it happens. This effect occurs using dedicated lines as an added benefit, though it’s seldom if ever expressed as such.
12-11-08: Blindjim