Shunyata DTCD (new way to measure power cords) - Page 3

I ran 2 large "Impact 2" semiconductor wafer probe test stations about 30 years ago..one day, while testing gate currents for some very small fets, the machine started giving leakages of 100 attoamps..normally the fets ran in the hundred picoamp range..this batch was whoa... I had to look up attoamp..


zepto...wasn't he one of the three stooges??
yocto...I loved the spiderman movies, but sandman was more fun.
Cheers, John

I think zepto was one of the Marx brothers, not Stooges. Although Stooges might be more apropos.

Zeppo was Marx Bros.
Zippo is a lighter.

Doc Ock is from Spiderman

jneutron is pictured here:

zepto is 10^-21 which is what your retirement will be worth.

I think that anyone who normally plugs their AC power cords into very large DC power supplies would love these cables!
If they connected 50 feet of heavy primary cable from their DC supply to a circuit breaker panel then 50 feet of 12AWG Romex to a outlet then to the AC power cord then to the test load. I doubt that any difference could be seen between their super-duper cord and any reasonable cord. Most homes probably have more than 50 foot power line runs.
Just think what a "power conditioner" would do to the test.
The AC wire runs are way to short to worry about characteristic impedance. The power companies pole pig transformer has poor high frequency response.

4 Dees, dude...

Don't Diss Da Doo!!


That is a fallacy promoted by those who can't be bothered using a rigorously accurate analysis of the real world.

Inspection of the problem by even the most casual of observers would show the distinction is not trivial...(love that phrase

Lumped analysis and "wavelength criteria" are useful tools for the layman. For REAL E/M-field people, it is a three legged dog..

Agreed. However, since you have not provided any data to support that statement (and I cannot provide any either), I had to perform the analysis such that the data was not required. My assumption that the load panel provided an infinite current source and zero impedance was sufficient to make the point that the wall outlet does not support the current slews that Shunyata used to distinguish their product.

Cheers, John

Doo-da
Doo-da

All de doo-da day.

I think that we agree that even with a perfect source Shunyata claims are overblown! With a real world source (even if the claims were close to true) the differences are meaningless.

It's been about 10 days since I first visited the Shunyata web-page. I believe that they are changing the editorial content in response to forum threads like this one. Some of the pages are different than I remember.

After revisiting the Shunyata web-page I realized that characteristic impedance would be a factor in their test. In one chart the "X" axis is in microseconds but without any values. On another page they write that the test signal is only 50 microseconds long.

It might matter in their test but with a 60hz signal it won't. Unless the cable is several hundred miles long.

Yes they are overblown. However, that said...

The test they perform is indicative of the external inductance of the line cord. Reduction of the external inductance will indeed lower the coupling it will have to a ground loop.

Causality is being confused here.

They would be remiss if they did not do such a thing. I would not accuse them of being stupid, far from that..

The devil is in the details, no? When I spotted the reference to microseconds on the origional ad copy, what they were doing was clear to me..

For supply cap feeding, which is specifically the scenario they depict.. that is accurate, their cables will not make a difference.

For loop coupling, no.

Unfortunately, Shunyata does not yet understand the distinction. If they are reading my posts, they may eventually.

They are even welcome to post on this thread, either in disagreement with me, or to ask me questions. I would not mind that.

Cheers, John

I noticed that Shunyata has added content to their "white paper" page. It now has more charts & graphs and some test conditions info. But still it has nothing to do with how a real world AC power cord works.