Is my speaker wire magnetized?

[wrenhunter]

Hi there

I have a strange problem I hope you guys can help me with. I have a 5.1 setup with a Marantz SR5000 receiver and CSW speakers. It's been working fine for two years. Every month or so, I run the "Test Tone" via the amp, to send a signal to each of the six speakers in turn and ensure that all are working.

This weekend, for the first time, one of the speakers did not "sound off" -- the rear right surround. I did the usual logical tests.

First, I swapped this speaker with the left rear surround, and repeated the test. Again, no sound from the "right" rear. So it's not the speaker.

Next, I swapped the speaker wire at the amp terminals, so that the left physical rear speaker was wired to the right rear channel. Ran the test again, and this time I got sound during the right rear test. So it's not a problem with the amp's innards or terminal.

Last, I cut a new 24" piece of the same 16 gauge copper wire and wired the "real rear right" speaker to its proper terminal, with the rest of the system as it had been. The whole test worked.

So looks like the right rear wire is the problem. I look down its run, and note that a large transformer (for a digital piano) is sitting square on the wire! Must have got pushed there during Thanksgiving guest/bed maneuvers.

So my question: could that have magnetized or otherwise messed with the wire? And if so, since I've unplugged the piano and removed the transformer, will the wire go back to normal, or will I have to replace it? Naturally, the problem wire is the longest run in the room!

Thanks,

David

[Resident Loser]

...of my knowledge, non-ferric materials (e.g. copper) , do not hold a magnetic charge...the wire may have been damaged, it's insulation crushed and the conductors short-circuited or one or both legs may have severed causing an open circuit...I would think the latter would be fairly obvious as the insulation would most likely show some sign...

Usually it would take a bit of weight for that sort of damage to happen, but hey...stranger things have happened...

jimHJJ(...self-healing wire?...not yet...)

[jneutron]

...of my knowledge, non-ferric materials (e.g. copper) , do not hold a magnetic charge


A magnetic WHAT????

Did you say.....charge???...magnetic charge???

He he...that made my day...not the word, mind you, just the fonts..:)

(I always confuse the ""non random re-alignment of magnetic domains in response to an external magnetic field stimulus" with the word "charge", the spelling is so so close..):)

Pay no attention to me, I'm having fun with this...

Their actually putting a detector together here to find magnetic monopoles..the room they use for meetings has a sign on it that says "war room".

I tink youse be right, he squasheded da wires..

When you said turkey poisoning, did you mean just "filled well beyond capacity" (as I did), or some bad meat? If the latter, hope all is well. If the former, serves ya right..

Cheers, John

[GMichael]

...of my knowledge, non-ferric materials (e.g. copper) , do not hold a magnetic charge...the wire may have been damaged, it's insulation crushed and the conductors short-circuited or one or both legs may have severed causing an open circuit...I would think the latter would be fairly obvious as the insulation would most likely show some sign...

Usually it would take a bit of weight for that sort of damage to happen, but hey...stranger things have happened...

jimHJJ(...self-healing wire?...not yet...)

When I saw the title of this thread and that you had responded, I was expecting a little more zip to your reply. But instead you were kind and helpful. Don't you feel well today? You're post is mostly sarcasm free.


But I agree, something got squished.

[Resident Loser]

...When you said turkey poisoning, did you mean just "filled well beyond capacity" (as I did), or some bad meat? If the latter, hope all is well. If the former, serves ya right..

Cheers, John

...thanks for asking...fat, dumb and happy...it's just that l-tryptowhatever...very relaxed...need more...want more...had turkey dinner X2...turkey-on-rye sandwiches...turkey salad w/bacon clubs...will have more sammiches and turkey salsa verde enchiladas...will freeze the rest for turkey croquets later on...

jimHJJ(...I do like roast turkey...a most wonderful time of the year...)

[Resident Loser]

When I saw the title of this thread and that you had responded, I was expecting a little more zip to your reply. But instead you were kind and helpful. Don't you feel well today? You're post is mostly sarcasm free.


But I agree, something got squished.

...seemed to be of a reasonable, if misinformed sort...I saw no reason to be otherwise...you elitist rat-b@st@rd!!!

And how was your bird?

jimHJJ(...if ya' don't mind me askin'...)

[GMichael]

......you elitist rat-b@st@rd!!!

Thank you for noticing.


And how was your bird?

jimHJJ(...if ya' don't mind me askin'...)

This bird? :dita:

Oops, sorry. But I've been dying to use that Icon for months.

The bird etc was/is great. Honey did a great job this year.
How's yours? (although you may have already answered this)

[wrenhunter]

Thanks guys (see where it says "Newbie" under my handle?). The transformer did not fall from a height -- at worst, it moved end over end once -- so I don't see how the wire could get crushed that bad, but oh well. Guess I'll replace it.

[Resident Loser]

...so nicely, calmly and quietly pointed out, it's not a "charge" at all...it actually would be residual magnetism...but since it's a non-issue, the point is moot, the beast is dead...well at least it was coughin' up blood this morning...I could have referred to it as the effect of gamma rays on man-in-the-moon marigolds, but since we're gettin' so techie-picky, in hindsight I thought a more accurate (if still dumbed-down) bit of nomenclature would be in order...

jimHJJ(...a thousand pardons to all and sundry...'ceptin' of course the Rush fanatic...Bird good...me cook it...22lbs. of butter-basted gobbler with sausage and wild rice dressing...details available on request...send a SASE to Eat-The-Bird@byte_me.org/html.gov...)

[hermanv]

One other possibility, contacts go bad, they do it all the time. When you removed the wires for testing you automatically made a new contact.

An Ohmmeter would confirm both continuity and lack of shorts if you own one.

Hey jneutron, using english speak instead of physics speak, couldn't you say a superconducting ring can hold a magnetic charge?:ihih:

[jneutron]

Hey jneutron, using english speak instead of physics speak, couldn't you say a superconducting ring can hold a magnetic charge?:ihih:

I thought I was using englishspeak:confused5: ....he he.

You are speaking about persistance currents, this is used when you want an extremely stable field. MRI's use this.

A "charge" has rather unique properties. If you approach it from any direction, it still looks the same. If you approach an electron, you see the negative charge (all the field lines go toward it), so if you follow the field lines, you get to the electron.

Same with positive charges.

The magnetic counterpart to an electron or a proton is called a magnetic monopole. If it exists, it would look like just a north pole, or a south pole.

A bar magnet has both north and south poles...all magnets in fact, have both, and they are called dipoles because there are two poles. And the field will be different if you approach it from different directions.

A ring of current creates a dipole field. So, it is not actually a magnetic charge, but a magnet with two poles.

Yes, we do confuse the issue by saying we've "charged" the magnet, or "charged" a battery or capacitor...but with magnets, there is not yet a magnetic charge, or monopole, which has been found.

It is postulated, and would make maxwell's equations fully symmetrical, but tain't been proven to exist yet. Some guys here are puttin an experiment together to look for them.

Cheers, John

[Resident Loser]

....off-topic...

Loudspeakers used as near-field radiators <6ft legs on the equilateral triangle...Each cab with dual woofers, dual mids, dual tweets...Tweets specifically... <5in. apart...one above the other...Can we readily discern those tweeters as individual point sources? Would any response (if there are any)/phase differences that might be caused by that mininmal distance (e.g. changing angles from driver centerlines to the listeners ears) be observable or would comb-filtering come into play?

jimHJJ(...jus' wunnerin'...)

[hermanv]

It is postulated, and would make maxwell's equations fully symmetrical, but tain't been proven to exist yet. Some guys here are puttin an experiment together to look for them.Cheers, JohnThey have all gone to south Florida, escaping the winter, swampland, ask those guys if they want to buy some.

[jneutron]

They have all gone to south Florida, escaping the winter, swampland, ask those guys if they want to buy some.

That would explain a lot:)

They're looking where they aren't..

Cheers, John

[jneutron]

....off-topic...

Loudspeakers used as near-field radiators <6ft legs on the equilateral triangle...Each cab with dual woofers, dual mids, dual tweets...Tweets specifically... <5in. apart...one above the other...Can we readily discern those tweeters as individual point sources?...)

I wouldn't expect so. Ears horiz, tweets vert, no sensitivity. Horizontal motion does not change the geometry other than the initial lobe pattern of the tweets.



....Would any response (if there are any)/phase differences that might be caused by that mininmal distance (e.g. changing angles from driver centerlines to the listeners ears) be observable or would comb-filtering come into play?

jimHJJ(...jus' wunnerin'...)

Vertically, combing could happen.hmm, lets play numbers (I like playin numbers)

speed of sound 13 kiloinches per sec
1Khz, 13 inches
10 Khz, 1.3 inches
180 degrees off, 3/4 inch
6 feet away, 5 inch spacing, 3/4 path length diff...

Sin theta=.75/5 = .15

Theta = 8.6 degrees..(simple calc, don't beat me for it..):)

This means that 8.6 degrees off axis for one will invert a 10Khz signal. This sets upper bounds on the lobe vertically. beyond that angle, the combing will drop in frequency.

As to relationship with other drivers, many already do that time/axis correction thingy.

Cheers, John

[hermanv]

I don’t know what’s so hard about finding monopoles, you just stick a south monopole on a stick (scotch tape will do) poke around in the dirt and a bunch of north monopoles will stick to it. Then you stick the north monopole on a stick and repeat to collect a bunch of south monopoles. A regular magnet won’t work because all magnets have an exact balance between south and north monopoles and an extra one just won’t stick. Easy, see, the only trick to it is finding that first one. :biggrin5: :biggrin5:

You guys, wasting all that government money. I mean how much can a stick and scotch tape cost? :biggrin5: :biggrin5:

[jneutron]

..... I mean how much can a stick and scotch tape cost? :biggrin5: :biggrin5:

Mil spec? Or reg'lar..

Cheers, John

[Resident Loser]

Mil spec? Or reg'lar..

Cheers, John

...you can get some camoflage duct tape...that way

You can take the north poles and
You can take the south poles
And they'll never know just what hit them...

P.S. thanks for the math...that's what I thought...

jimHJJ(...who am I kiddin'...)

[wrenhunter]

So, an update better late than never ... I took HermanV's advice and bought a multimeter and tested the rear surround contacts. The good one (left) shows a few ohms, bad one (right) has 0.00. Thank you Radio Shack for proving the laws of physics have not changed -- one of their sacred duties, right?

Could get it fixed, I guess, but it is 5 years old, and I need more optical and video inputs anyway. Nice excuse for a new one!