The Truth About Power Cords and there "Real" Price to Performance

delkal,

You are confusing frequency of generation with frequency of power draw. Linear power supplies may draw power 120 times per second (rectified), but the bandwidth of what they draw is not at all limited to 60Hz but has harmonics well beyond 60Hz. If that was not the case, linear power supplies would not work. It is akin to a 60Hz square wave not being only 60Hz, but having significant energy at harmonics of 60Hz. Is it noise? ... matter of definition I guess, but it is certainly an artifact of a linear power supply. The power draw for a linear power supply will always have significant harmonic content.

A switch mode power supply on the other hand may draw power at  something approaching 60Hz, at least many attempt to.

geoffait- To get a speaker to produce sound you need an oscillating current of some frequency and AC power is distributed as an oscillating current at 60 Hz. Do you ever wonder why a 60 Hz ground loop hum from the AC sounds exactly the same as a 60 Hz audio test tone?

AudioZenoligy- A 60 Hz signal starts out at zero volts, increases to positive voltage, decreases to 0 again then goes to negative voltages, then back to zero. This cycle happens 60 times a second (60 HZ). Linear power supplies draw on the positive swings and the negative swings. There is no power when it crosses zero. That is where you get the mistaken idea that there is any energy at 120 HZ. There isn’t. 120 Hz is just half of the 60 Hz full cycle.

Harmonics is still distortion and for power distribution and is not OK. Ever. And even with an audio signal going to your speakers harmonic distortion is only a minor component. While some distortion / harmonics can be considered OK (like the distortion in a tube amp) if your system has more than one percent you might want to consider upgrading to high fidelity.

It is ironic that many of the most vocal people in this thread do not seem to have a basic understanding of how power and audio signals work.  Further debating is pointless.

Delkal,


I have been respectful to you but your attitude is poor and your knowledge worse.


The AC supply is a voltage at 60Hz. However the frequency of the power draw, i.e. current, is a factor of the load effectively modulating the line frequency. Hence you have current draw both at 60hz, and at many harmonics of 60hz, primarily odd harmonics the spectrum dependent on the load.


I will emphasize again a linear supply cannot work if it draws power only at 60hz and you are confusing supply voltage frequency with power draw frequency. The lack of knowledge is not mine, it is yours. (Note I said that it draws power 120 times per second not that is the primary spectrum of the energy draw). 


Short of a resistive load just about nothing on the AC line has low distortion. 


It would not be unusual for a linear power supply in a piece of audio equipment to be running 30% or more harmonic distortion on the AC input current. Only way to fix that is to add resistance or inductance to the AC input lines.

Atdavid
...the #1 lesson that an audiophile can learn is that they are susceptible to bias.

 
What I can't stand is those who say my evaluations of my system upgrades are so heavily biased as to be unreliable, or even delusional. 

thyname
It's beginning to look like it. To the point of me starting to detest is, as only [the slayers of snake oil] use it, in every audio forum they can find.

There are members I detest, and whose comments I no longer read.