how can a line cord affect frequency response ?

The power cord doesn't affect frequency response, however it can affect dynamics and in some cases become an antenna for RF. When RF gets into your amplifier, then it can affect the sound in many ways:bright, lean, hard, glassy, etc. Normally, the power supply should eliminate these effects, but in some cases, it doesn't.

It never ceases to amaze me just how cheap some expensive amplifiers can be. Some factory power cords are really inexpensive. When you replace them with better quality ones, there can be a small difference in DC levels in the power supply, which you will hear. However, none of this will affect frequency response.

Whether or not you will get the same effect(s) with a Belden 14 gauge shielded power cord for 10 or 12 bucks is a whole different matter.

I have followed this thread closely and until now have not felt like saying anything. But the last post by Sp has sparked me to reply.

Over the past ten years or so I have listened to atleast 100 or more power cords in my system. Never satisfied with the results, I started building my own. At last count, probably 30 samples. Every type of wire, geometry , shielding method and terminations imagineable.

None of my final designs, with the execption of (1) are shielded. Shielding, IMO adds an audible coloration that I find quite annoying.

The question, "how can a line cord affect frequency response?"

Based on my experience, the #1 factor by far is the type of conductor material the cord is built of. Everything else is secondary. How?, the same way an interconnect does. Use conductors that restrict bandwidth and the frequency response will be adversely affected.

Reb1208:

In the context of audio power supplies and the power cables that connect them to the wall outlet, please explain how bandwidth relates to anything other than line frequency, eg 50/60 Hz.

what about resistance ? suppose you design a poer cord with very high levels of resistance. will that affect treble reponse ?

or, suppose you design a power cord with a very high level of inductance, what then ?

Spatialking,

Not sure if I completely agree with the power cord acting as an RF antenna. Once energized, it has more rejection qualities, and is more susceptible to large electro-magnetic field influences. Even placing two energized cords along side each other, will have little or no effect on the other's audio component. The newer switching class-D amps can inject adequate hi-freq noise into close-proximity sensitive interconnect cabling and component gain stages (even through some cable shielding and metal chassis), but would be hard pressed to have an audible affect when placed several yards up stream, along side another amp's un-shielded PC (via an extention cord for testing purposes). Oh, and can't forget about all the non-shielded Romex behind the sheetrock walls. Mainly what people hear from two-way radio communication, is affecting radio/television receivers or inadequately shielded sensitive components and IC cabling. That's the only time I've ever heard anything during audio playback, and I live next to a private air park where communication takes place throughout the day. I'm open to explanation, though.

Reb1208,

Regarding conductor materials... copper, silver, or gold are capable of frequencies into the extreme RF bandwidth. The audio bandwidth is child's-play in comparison. Copper is utilized everywhere in these applications. Capacitance, impedance, and shielding are the main issues affecting an interconnect's frequency/performance, as they do with RF cabling or wave-guides.

Not real sure how or why you're having issues with shielded cords creating coloration. Any further explanation to help us understand what might be contributing to your findings?