I finally learned why powercords make a difference

While sitting for many hours at the CES together with Mr. Strassner of HMS I took the opportunity to ask him the question which seems of importance for most audiophiles:
Why do power cords make a difference? Or in other words: Is it really important to spend a considerable amount of money on the last 6 ft in the form of power cords, if you have hundreds of feet of inferior cable running inside the wall? So why would a 6 ft power cord justify the expense.
Because I want even to give the audiophile layman a chance to understand why it indeed does make a difference to use a good after market power cord and why this investment is justified, I will use a rather simple language and explanation. The real problem is a bit more complicated of course.

There are two things a power cord has to take care of:

Low frequency distortions,
High frequency distortions

Low frequency distortions:

I assume it is a known fact that all components have to be fed from one common source (or having one common potential) to avoid a so called voltage differential, which will cause distortion. So since all components are either fed from a common wall plug or a power wing or powerstrip with 6 or more outlets, there is almost no voltage differential going on inside the wall, since all is going on the same potential, inside one cable.
The key to understanding the issue is that as soon as you have a voltage differential between components, you will have currents running through the interconnects, which connect the components, trying to equalize the voltage differential, trying to bring it to zero. These equalizing currents cause low frequency interferences, which will harm the sound. Now inside the wall you have no voltage differential, since all components are fed through the same source.
But once you connect your two or more components with power cords, you start to have different voltage drops on each single power cord, since now the one cable (your inside wall cabling) is branching into two or more lines (at the powerstrip of course) to feed your components. This results in a voltage difference between the components.
There is also a resistance between each power cord plug and the sockets of the powerstrip and the components of course use their voltage needs not at the very split second, but have a different current demand. So all of this is now causing a voltage differential inside your components and since the law of physics dictate that this voltage differential has to be brought to zero, equalizing currents start to flow between the components, through the interconnects. So you can easily imagine that these currents will harm the musical signal, so power cords have to be built with a low ohm and inductive resistance to bring down these currents as low as possible.
This is the first reason, why audiophile components need good power cords.
But we do not only have low frequencies, which have to be addressed by power cord builders. There are also two sources of high frequencies distortion, but is seems that most power cord companies have failed to address this important issue:
The first reason is that each power cord will always act as an antenna, picking up all sorts of high frequency signals, from your neighbors computers to cellular phone or radio signals. And this pollution of high frequency signals will only get worse in the future.
So here you need several filter elements, which will let you filter out these distortions. A passive version is just not very efficient.
But there is another culprit for high frequency distortion, ruining your audio signal. These are high frequency signals caused by the very audiophile components you use. These interferences, (whose end product is ringing or distortion) are either caused by your CD player, or by your amplifiers, since they do not have a steady power demand, but pulsate, since the power demand varies according to the dynamics of the music.
So in very simple terms, this pulsating of the power supply of your amps will also cause high frequency interferences, which are being fed back into the system, harming and ruining the musical signal. This is a serious problem and you will need a filter solution to rid your system of these problems.
So in very simple terms above mentioned problems have to be addressed by your power cord and the better a power cord can handle all three problems at the same time, the better your system will sound.
So these are the reasons why good power cords, are extremely important in a good audiophile system.
Great! So we have 3 things to consider:
1. Current loops
2. EMI and RFI
3. Componant interferences
It is a lot to ask of a power cord alone to fully address these 3 items.

Current loops are caused by design factors inside the componants as well as power cord impedances, and these may have to be addressed with balanced interfaces, power conditioning and interconnect isolation transformers. EMI and RFI are always present in the power source and can be best eliminated with filters at the wall outlet. Componant interferences are best minimized by separating the ac circuits for the objectionable componants.

While a well designed power cord may reduce current loops, and filter some EMI/RFI, and hold back some componant interference, it is hard to believe it could do a better job in tough situations than with the help of some combination of the above. There are other considerations such as power conditioners that can't keep up with the current needs of large amplifiers, and isolation transformers that color the signal, so I'm not saying this is simple. Every system also has a different mix of the three, so there isn't necessarily one solution.

So I believe you need a systematic strategy to determine which mix is best for you. Did Mr. Strassner offer such a strategy?
From an electrical engineering standpoint, there a few problems with the arguments.

First, lowering cord resistance does not lower the currents. On the contrary, it would increase them according to Ohm's Law since you state the voltage differential is between the amp and outlet - surely an error in logic here. Second, for the cords to eliminate the differential voltages, there would have to be a special LC filter involved that dissipates to ground - which is not the case since a cord is a cord (however, perhaps MITs do?). Third, if the power supply is any good, the differential voltages will be miniscule anyway and the error will be taken out of the amps, and not the cords, since they are the only ones that can sink the difference effectively. Thus, the cord does nothing to help here either.

The biggest effect a cord can have is shielding (and definately not filtering as the argument states) from EMI which is present for sure in bad power supplies. I beg to differ with the cord designer but he is also a business man. I am an electrical engineer that deals with these sorts of things daily doing research on high-power power supplies and so have to be very sensitive to these things. The cords don't do much but shield as I said above. This may account for the sound differences people hear, and then again, it may be psychological (I am dodging the tomatoes ;).

There will be differing opinions on this but mine is strictly from a technical viewpoint. I can fill in with great detail for those who wish to email me privately about it. Arthur
Aball, since you stress so much that you are an electrical engineer and Mr. Strassner a business man, let me tell you please that his audiophile business is only one part of the story.
He is also an engineer (although that does not mean anything by itself) but he has been designing scientific amplifiers and cables since 20 years, which even the NASA is using in their research programs, and whenever a company needs to do extremely sensitive experiments, they, world-wide turn to HMS for their products.
So he knows a little bit about power cords and cables.
The problem lies more in the fact that English is neither my nor Mr. Strassner's native language, so to convey these rather difficult facts in a foreign language is the biggest barrier.
We are working with a known reviewer who is fluent in German and English to help Mr. Strassner come out with a much more scientific statement about why power cords work and then engineers like you will have a chance to discuss this subject on a far more scientific level, with the reviewer serving as interpreter. And we eventually plan to publish such a discussion, so the audiophile community will have far more detailed pro and cons about the need of a power cord in an audiophile system.
For the record, English is not my native language either but I think we understand each other well enough....

I am anxious to hear all about it from Herr Strassner himself.
Aloha Christian,

Did you get my email about the digital cable?


Not to start World War III, Tekunda, but shouldn't you mention somewhere that you are the U.S. distributor for HMS cables?
I have to agree with Aball. There are some flaws in the thinking here. You cannot expect a power cord to go against basic electrical concepts, I don't care how sophisticated it is. Also, trash that is picked up on the line before the "Official" power cord remains on the line unless it is filtered. Most "Good" power supplies compensate for noise. The transformers used in amps are generally of the "Isolation" type which means spikes, etc. will not pass anyway.
I too feel the best you can do is design the cord (by shielding or whatever) to not pick up extraneous noise from its enviroment.
CD players DAC's can add a lot of noise on the line itself and through the power distibution network. I had a McCormack one time that would render the TV unwatchable with noise (both transmitted and line based.)
I believe any perceived difference(real or imagined) lies in lowering the noise floor(or at least changing it.)
Dopogue, yes you are right. I thought my first sentence was expressing this, but if somebody does not know me, he will indeed have no clue that I am the importer of said cables.
So, yes, I am the importer of HMS cables and please read everything I write about said cables with a grain of salt, since I could be biased.
Bigtee, you write: "Also, trash that is picked up on the line before the "Official" power cord remains on the line unless it is filtered"

I agree with you totally and that is why HMS has built-in several filters in its power cord in a so called Top Match Box, to filter out the trash of high frequency interference with six user selectable settings.
But I did not want to mention this in my first post, as people would maybe claim I am boasting and misusing the forum, by telling that HMS has indeed such filters implemented in a box, which is connected with the power cord.
Hi to everyone!

I'm always interrested in writings about power cords. And I like this discussion.

What I don't understand is why people must have an technical explanation about something to believe it? Either you hear the difference or not. I believe that, when some day, a valid and accepted technical explanation is there it will not help you to hear it better!
But don't waste yor precious lifetime waiting. Listen and you'll know "if" it works for you...

Best regards,