The Smith Chart and...Power Cords

Puma Cat

Puma Cat

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Just came across this video on YT today on the Smith Chart.

When viewing this video, it immediately became clear why aftermarket power cords can provide such an improvement to our audio systems.

Here's an example what happens when the impedance of the "transmission line" does not match the "load impedance". This mis-match causes a "reflected wave" on the circuit, which you don't want to have, as described in the video. Note how the red dot is "off-axis" to the center-line of the polar plot.

Smith-Chart-1.jpg


Now, when you have the PC's impedance matching that of the "load", you get a much more ideal response, as shown by the red dot in the plot, meaning, no "reflected wave", which is exactly what you want.

In our case, transmission line is the PC from the wall AC receptacle, and the "load" is the FWBR* power supplies inside our amplification components.

Smith-Chart-2.jpg


And...this is key reason why well-designed aftermarket PCs can provide such an audible improvement in our audio systems: because they can help "match" the impedance of the "transmission line" with the "load".

Don'tcha just love...SCIENCE? :D

*–FWBR: Full-wave bridge rectifier
 
Oh dear, oh dear!
HAM radio operators know that AC cords make poor radio antenna cords.

The power company knows that the above chart applies to city-to-city AC power transmission.

* * * * * * * * * *
and even if it does apply to shorter circuits.
Your transmission line starts at that big power company transformer down the street and ends at your hi-fi component.
I don't think that the power company is interested in replacing all that cable.
And Oh, each of your components has a different input impedance and a power amps impedance changes with how much power it's delivering.

Stay away from YT videos.
 
Last edited:
And wait, there's more!
They used the wrong formula for determining the 'Radio Frequency Characteristic Impedance' of the AC cord.
They used the short form formula, which is only good at above about a half Megahertz.
If the used the correct (long form) formula, they might find that the cord's 60 Hz impedance might be near 1000 Ohms.
 
Speedskater said:
Oh dear, oh dear!
HAM radio operators know that AC cords make poor radio antenna cords.

The power company knows that the above chart applies to city-to-city AC power transmission.

* * * * * * * * * *
and even if it does apply to shorter circuits.
Your transmission line starts at that big power company transformer down the street and ends at your hi-fi component.
I don't think that the power company is interested in replacing all that cable.
And Oh, each of your components has a different input impedance and a power amps impedance changes with how much power it's delivering.

Stay away from YT videos.
Click to expand...

But why? They’re so much fun! :P

Thanks for the additional info.
 
Speedskater said:
And wait, there's more!
They used the wrong formula for determining the 'Radio Frequency Characteristic Impedance' of the AC cord.
They used the short form formula, which is only good at above about a half Megahertz.
If the used the correct (long form) formula, they might find that the cord's 60 Hz impedance might be near 1000 Ohms.
Click to expand...

Thanks for sharing the facts about the nonsense that was posted about power cords matching the impedance of the electronics they are attached to.
 
Good rebuttal 'Speedy' and while I doubt Stephen was trying to lead us astray it does point out the fact that there is a ton of BS on YouTube. !
 
Mikado463 said:
Good rebuttal 'Speedy' and while I doubt Stephen was trying to lead us astray it does point out the fact that there is a ton of BS on YouTube. !
Click to expand...

I found it interesting and mentioned it here because it points out a key principle that I’d point out when teaching DFSS to my fellow scientists and engineers: to be mindful of the nature of interactions of various factors for scientific and engineering applications, that many times it is not one factor or another that are key in mediating a functional response, but the interaction of those factors. A classic one in chemistry is the Time*Temperature interaction.
 
a.wayne said:
Any calculations for why silver cords sound different from copper :)
Click to expand...

Most likely because of this…

Copper atoms have 29 electrons and the shell structure is 2.8.18.1.

electronic_configuration_Cu.png


vs. this: Silver atoms have 47 electrons and the shell structure is 2.8.18.18.1.
electronic_configuration_Ag.png
 
Oh dear, oh dear.
not again!

It's a series circuit from that big power company transformer down the street to your amplifier.
Replacing 1 percent of it won't change anything.

If you hear a different, there was some overlooked uncontrolled variable in your test.
 
Speedskater said:
Oh dear, oh dear.
not again!

It's a series circuit from that big power company transformer down the street to your amplifier.
Replacing 1 percent of it won't change anything.

If you hear a different, there was some overlooked uncontrolled variable in your test.
Click to expand...

Have a nice day! Cheers.
 
What a load of unscientific bollocks!

If the transformer in the amp or DAC needs 240 /110 volts at 50/60 cycles per second and the power cord supplies just what it wants, it'll be very happy, thank you.

There's a small chance that RFI may be introduced between the wall socket and the amp - the last few feet of the power supply - so there is a weak case in some dirty (electrically) homes to shield the power cables. If this happens to be a concern then a belt and braces answer is to use Belden 19364. Another good reason for using this excellent cable is that you can make each cable exactly the length you need. This inexpensive cable is absolutely all the transformer needs, even in dirty homes, and any more money spent on power cables is better spent on just about anything else! Buy your wife a lovely bunch of flowers or take your girlfriend for a nice meal out - either much better value for money!
 
Well all that blah blah blah can be sent off with one compare , sighted or unsighted , PC do make a difference , the why can be sourced or rubbished , fact is they do make a difference ..!

The lofty prices is another debate entirely...


Regards
 
Speedskater said:
Oh dear, oh dear.
not again!

It's a series circuit from that big power company transformer down the street to your amplifier.
Replacing 1 percent of it won't change anything.

If you hear a different, there was some overlooked uncontrolled variable in your test.
Click to expand...

There’s a reason why the last 3 ft or so makes a difference from wall outlet to amp socket.. nothing is in isolation ..


Regards
 
a.wayne said:
There’s a reason why the last 3 ft or so makes a difference from wall outlet to amp socket.. nothing is in isolation ..


Regards
Click to expand...

Give us a clue - please! Unless it's something I covered in my last message. And please allow the Laws of Physics to have a say! ;)
 
a.wayne said:
Well all that blah blah blah can be sent off with one compare , sighted or unsighted , PC do make a difference , the why can be sourced or rubbished , fact is they do make a difference ..!

The lofty prices is another debate entirely...


Regards
Click to expand...


translation / interpretation ............they can be 'made' to make a difference and any properly constructed PC need not cost an arm and a leg !
 
Hear Here said:
Give us a clue - please! Unless it's something I covered in my last message. And please allow the Laws of Physics to have a say! ;)
Click to expand...

Read this: WHY POWER CABLES MAKE A DIFFERENCE | Galen Carol Audio | Galen Carol Audio

and...
a.wayne said:
Well all that blah blah blah can be sent off with one compare , sighted or unsighted , PC do make a difference , the why can be sourced or rubbished , fact is they do make a difference ..!
Click to expand...

They do indeed. How 'bout some..data?

Watch this...
Shunyata Research noise-reducing power cord demonstration - YouTube

and this...
V14D Demo Part 2 - YouTube

Have a nice day and a great weekend, gents. :thumbsup:
 
Puma Cat said:
Read this: WHY POWER CABLES MAKE A DIFFERENCE | Galen Carol Audio | Galen Carol Audio

After reading that, how 'bout some..data?
Shunyata Research noise-reducing power cord demonstration - YouTube

and this...
V14D Demo Part 2 - YouTube

Have a nice day and a great weekend. :thumbsup:
Click to expand...

Sorry but an article written by a particular high cost "audiophile" supplier is hardly likely to be unbiased or even accurate. The sentence that reads: "The first question is – do power cords make any difference at all? There is no sense in talking about theories of operation if we can't agree that there is an audible effect." says enough for me to read no further. We can't agree there's an audible difference (supported by the Laws of Physics), so sorry, it's still a load of bollocks!
 
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