how can a line cord affect frequency response ?

Regarding RF: I didn't mean to imply the line cord acted like an RF antenna when it was powered. What I was trying to say, however vague, is that it can act like an antenna and pick up RF energy. Although this energy should be eliminated in the transformer or perhaps some RF network in the PS input, there are cases where it can actually get into the amplifier itself and cause sonic problems. In this case, switching line cords may or may not make a difference. However, that being said, you still have lots of ROMAX in the walls which can pick up RF, too.

Dpac996: I believe you have bandwidth of the amplifier and bandwidth of the transformer, line cord, diodes, surge capacities, line droop, line drop, and dynamic compression all mixed up. Amplifiers simply don't work the way you describe. The power bandwidth of the transformer is typically no where near the amplifier bandwidth and sometimes it is not more than 47 toi 63 Hz. The line cord has wider BW to be sure, but keep in mind the only frequency on the line cord is 60 Hz, at least in the US.

Metro04: I do agree that materials do affect performance, but not like interconnects. Line cords only carry one frequency, 60 Hz here in the US. Interconnects can carry bandwidths from DC to 100 MHz with ease, if you use the right one.

Reb1208: Actually, if a line cord were to really seriously limit the power amp enough that it began to get warm and soft, it is more likely that dynamics will be compressed, rather than bandwidth. You might find that the low frequency peaks, not the high frequency peaks, is what got clipped. However, bandwidth below clipping, will be unaffected.

After writing that last night, it occured to me I should also elaborate a bit. When I said bandwidth, I was speaking in terms of the amplifier bandwidth, and I still state that line cords do not affect it. But since we are discussing line cords, let me relate the term "bandwidth" to line cords.

First of all, there is a voltage bandwidth and a current bandwidth but they are not the same. With respect to a line cord, the voltage bandwidth needs to be only a few Hertz wide, say 58 to 62 Hertz or so. Although the voltage bandwidth is much more than this, it doesn't have to be as long as the line cord can pass 60 Hz without loss.

The current bandwidth of the line cord, however, has to be much wider. In this case, a bandwidth from DC or a just a bit higher than DC to at least 600 Hz or so will do the job. The current BW can be higher than this without any problems.

I think I will start a new thread regarding line cord bandwidth as there is much to explain and it is really off topic from this one; probably next week sometime.

Spatial King,
I was describing the very basics of amplifer power supplies, paying particular attention to the rectifer output/resevoir cap.

I know that the power bandwidth of most amps easliy extends beyond 20 kHz.
Perhaps I did not articulate my thoughts precise enough, but I was not suggesting that an ampllifer's bandwidth is the same as the transformer.
I was purposely not getting into too much detail.
The question that Mr Tennis asked was how can ac-line cords affect frequency response. My simple answer is: I think that if there are ferrites or other inductive material involved in the construction of the cord, the inductance of this particular ac-cord may impede sudden fluctuations in current.

At the crest of the rectifed pulse, ie the charging pulse, the secondary of the transformer is now dumping current to the cap and the output device. It has to be this way or Kirchhoff's current law is full of hot air, which is not the case. The point I was trying to make is that during this brief moment the required current must ultimately come from the ac-line. If the ac-line is heavily inductive the instantaneous current performance may suffer.
I have never tested this theory on a real amp with different power cords. I have done circuit simulations in PSpice and i'm just throwing this out there as one way high frequencies or dynamics may be affected by PC's.

Spatialking,

What technical articals are you extracting your "voltage bandwidth" vs "current bandwidth" findings from, with regards to this topic and powersupply requirements?

i had this experience yesterday.

i was listening to my stereo system using an all copper line cord, gold furutech connectors, no solder connections, some dampening material in the cord feeding a tube amp.

i listened for a few minutes and changed the power cord. the second cord, had the same connectors, method of connection, dampening material, with copper and gold metals.

i heard a difference--a shift in the frequency response.

one line cord seemed to provide more extension top to bottom, while with the other there was some attenuation at the frequency extremes.

can anyone offer an explantion ?