[chbot] Measuring capacitance of audio cables

[Helmut Walle]

Would a meta-study count as scientific work, too? That would get him around the need to take 
measurements himself, and the outcomes could potentially be more comprehensive and practically 
meaningful than measuring a necessarily very limited number of samples... just an idea.

And a general note regarding all electrical cables: the metal - mostly copper - is usually the 
costly material in comparison to the plastic insulation materials. So the manufacturer can save 
money simply by using less metal. That makes the cable not only cheaper but also lighter and 
therefore less costly to ship, saving cost again... But obviously using less metal drives up the 
cable's impedance, and high cable impedance is undesirable for most applications. Based on this 
alone, you would expect better cables to cost more.

Furthermore, as an alternative to measuring capacitance and / or impedance, these values can 
also be calculated if the profile of the cable and materials are known. It isn't all that hard 
to cut an audio cable cleanly to take a look through a microscope to measure cross-sections or 
diameters. Assume the wires to be copper (even if they have a bit of silver plating or similar), 
and make some educated guesses about the plastic insulation material used. It would also just be 
interesting to see how much copper you get per $ spent - if the market economy works as it 
should you would expect to pay a certain base price per meter, plus a certain increment per 
additional quantity of copper. (If something costs much more than you would expect based on 
this, let's call it brand hype, unless they can justify the higher price due to their machined 
gold-plated connectors.)

All the best for the project!

Helmut.

On 08/09/2020 09:38, Paul Willmott-Dalton wrote:
> Hello all
> 
> I am trying to support my 14yo boy with his homework but am a bit out of my depth. He is aiming 
> to demonstrate understanding of the scientific method. To do this he wants to make a comparison 
> of the electrical properties of different brands of audio cables. His hypothesis is that there 
> is no difference between 'audiophile' cables vs cheapies.
> 
> I under that folks talk about capacitance being a variable. I'm told that this will be very 
> small in any cable and potentially difficult to read (in the tens of pF range).
> 
> Does anyone out there have the equipment necessary to do this? If so, could we bring some cables 
> to you for testing?
> 
> Kind regards
> Paul Willmott Dalton
>