Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics.

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Propeller Head Plaza ]

---

[ Alert Moderator ]

---

Re: What am I missing?

Posted by jneutron (A) on June 13, 2006 at 06:34:06

In Reply to: What am I missing? posted by Ted Smith on June 10, 2006 at 06:15:23:

Ted: ""
Perhaps I threw things off by using the word inductance instead of reactance. But I didn't think it would matter because I was just pointing out to Pat D that some people are worried about the audible effects of coiling your speaker wire.""

Proper use of the terms is important.

The inductance will not increase as the zip is coiled. The external field of the pair drops off as r^-2, the susceptibility of a zip also drops off as r^-2, the net result is a distinct lack of inductive coupling, both by equations, and by actual measurements.

The capacitive reactance for a zip pair can be increased by looping, it can be almost doubled. However, since the capacitive reactance of a zip cord geometry is so low in comparison to the inductive reactance, it will go unnoticed.
Ted: ""
In one thread you tell me that I will get audible distortions from a pair of wires (geometry unspecified) running parallel to another for, say 50'. (On the order of 1 in a 1000).

In another thread you say there will be 0 (!) effect from a pair of wires (geometry unspecified) running parallel to it's self for 13'.""

Ted, you have to keep all discussions in proper context.

In the first thread, we are discussing the coupling of a power loop running 20 to 50 amp peak haversines in intimate proximity to a ground loop which affects the ground reference of a piece of equipment with a power gain close to 5 orders of magnitude. In the second case, we are discussing the mutual coupling of a pair of dipole radiators, with a gain that can only approach a limit of 1/4 due to proximity and geometry issues.

The only thing that is consistent between the two is wires, electrons, and field theory. the level of effect, however, differs by almost 6 orders of magnitude..so it is useless to compare them as you have.

Ted: ""
Now, perhaps you know the geometry of the 2nd case. But to use a blanket statement that there is 0 effect seems uncharacteristically black and white for you.""

No, as you can see, the differences between the cases are quite drastic.

Ted: ""
Even if everything is linear the effect could be (by your own numbers), say, 1 in 4000 in a circumstance that seems to me to be much more direct and audible (e.g. a direct speaker connection vs. thru a random topology of power supplies, ground loops, etc.)""

It is entirely useless to assign relative levels to the problem, as that leads one down the "all these inaudible things adding up" schtick. To do so gets us to the silly arguments about grain boundary collisions, piezo effects in speaker wires, motor generator stuff...all stuff which ends up 5 to 8 orders of magnitude below audible thresholds. (despite still being professed as valid by the occasional person).

That "random topology" you speak is the primary reason for ground loop induced hum. To continue with your statements that ground loops either don't exist, or are of no consequence, is to insult all who have experienced system hum as a result. You are telling them that it's all in their mind..I don't believe that is your intent..

So, ground loop issues are quite valid.

Cheers, John

PS..this is the third time I've posted this, guess the forum is still hiccuping..

This post is made possible by the generous support of people like you and our sponsors:

VH Audio

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---