Guitar cables and their effect: WYSIWYG!

[frenchfries]

In the past, I have done an article for the previous version of "The Stompbox. net".
I had painfully tried to explain how a guitar cable behaves like an "unexpected EQ" because of its capacitance.
I had illustrated this article with my own screenshots of frequency analysis (and my results had been judged "wrong" by someone who wanted to disqualify me)...

I'm happy to post now this link that I'm found yesterday (and I thank Atlantic to offer inconsciously such an echo to my old article):

http://www.aqdi.com/cgi-bin/database.cgi

You'll be able to see AND to listen what a guitar cable does with the tone of your passive pickups.

Towards the end of the page, there's also an interesting applet: "How does capacitance affect the tone?"

Enjoy!

[JWDubois]

As an engineer who as to deal with the effects of cable capacitance to sensor response in industrial installations, I can attest to the effect of cable capacitance being real. Adding parallel capacitance to an L - R circuit (pickup + volume pot) forms a parallel resonant circuit. Note that changing the volume pot changes the frequencies as well, which is why some people use "treble bleed" circuits. Note also that if you use the guitar tone controls, you are swamping out the effects of all but the worst cables to a large extent.

The "Zerocap" cable is interesting. Since it's powered, if its not just a simple buffer circuit they may be using a technique called "guarding". In this technique, you drive the shield with a buffered signal, so that the signal conductor and shield carry the same potential. Since there is no voltage difference between the conductors, theoretically there is no capacitance between the conductors.

Here's an interesting app note from AD that discusses this:

http://www.analog.com/static/imported-files/application_notes/41727248AN_347.pdf

JWW