LAK 2-14-2017 I think it’s [prioritization of power cord upgrades among different kinds of components] a matter of system synergy and probably other technical aspects of equipment that I’m not capible of explaining but I’m hoping other more knowledgable will jump in here and explain it for us?
From a technical standpoint what I would find surprising would be if there **were** a high degree of consistency among reports of where in a system power cord upgrades are found to be most efficacious. There are simply too many dependencies and interactions that are involved, relating to the designs of the specific components, how they are interconnected, the technical characteristics of the particular power cords, and the voltage and noise characteristics of the incoming AC. Many of these dependencies and interactions, such as those involving electrical noise, have little if any predictability.
To cite just a few examples:
1) Bandwidth differences among power cords will affect different components differently. Wider bandwidth may improve the performance of many power amplifiers and integrated amplifiers, due to increased responsiveness of the cord to abrupt changes in demand for current (Shunyata has published some interesting papers and measured data on this), but may increase the bandwidth and overall amplitude of electrical noise that may enter or leave the component via the cord. Responsiveness to abrupt changes in demand for current will be significant mainly in the case of power amplifiers and integrated amplifiers, to a degree that will vary depending on their bias class (A, AB, or D) and on how much internal energy storage is provided in their design, among other design-dependent variables, while having little if any significance in the case of line-level components. On the other hand, power amplifiers and integrated amplifiers can feed significant amounts of electrical noise back into their power cords (as can DACs, CDPs, and other digital components), and bandwidth limitations in a power cord presumably may be helpful in limiting how much of that noise may couple into other components in the system. So there are design-dependent tradeoffs that come into play.
2) The significance of differences in shielding effectiveness among different power cords will depend on the amplitude and frequency spectrum of RFI that may be fed back from a particular component into its power cord, on the paths that may be available for that RFI to couple into other parts of the system, on the RFI sensitivity of other parts of the system, and on RFI that may be picked up from other parts of the system. All of this has essentially no predictability.
3) Voltage loss due to resistance in the cord will vary depending on how much current is drawn by the component, and a given amount of voltage loss will certainly have differing effects depending on the function and the design of the specific component. And of course differences in the AC line voltage at different locations will further lessen the predictability of all of this. In past threads, btw, Ralph (Atmasphere) has described having measured remarkably large reductions in the power capability of certain amplifiers resulting from relatively small voltage drops across some power cords. While line-level components having well regulated internal power supplies, and that draw minimal amounts of current, will likely have no sensitivity to this.
And of course all of this is in addition to the variables of listener preference, the intrinsic sonic characteristics of the components in the system, room acoustics, preferred listening volumes (which can affect the frequency response characteristics of our hearing mechanisms), the kinds of recordings that are listened to, etc.
Regards,
-- Al
