[sdiy] O/T Hi-Fi Snake Oil - UKP700 power lead

[Colin f]

> Hardest is the "double blind" part, where neither the tester 
> *nor* test subject know which component is playing. How would 
> you change a power cord in an audio system without anyone in 
> the room knowing that you changed it (including yourself)?

You need some automated switching under control of the software that makes
the random selection of X from A and B, and tracks the subject's selections.
For a power cord, you could build a box with some relays to switch over the
earth, neutral and live connections at the wall and device ends of the test
and control cables.
No doubt some audiophile types would claim that the addition of the relays
to the system would 'mask' the benefits of the cable...

A possibly interesting side note about ABX testing...
I did a lot of testing some time ago to determine what level of timing
errors I could hear in a MIDI-controlled synth.
There were a couple of cases where I was convinced that I couldn't hear any
difference at all, and basically felt I was guessing the answers.
The result of the test was that I *was* reasonably accurately picking the
correct source, something like 70-80% of the time.
Which suggests that I was hearing a difference on a sub-conscious level that
was influencing my 'guesses'.
So even if you don't think you can hear a difference, it's possible you can.

Cheers,
Colin f