Therein lies your error. Shielding does not stop magnetic field coupling of twisted pairs in the audio band. As I said, the EMC guys do not consider twisted pair magnetic coupling because they think of twisted pair as having coincident current centroids.
Do you need a dictionary??
You stated measurement.
I constantly stretch my imagination far beyound anything you can fathom..
I imagine the day you understand this technical stuff.
Given your previous demonstration of lack of understanding on how to measure something as simple as inductance, and the thought that you are on a committee which determines standards for the industry, I'm far busier looking up abject terror..
bada boom
jn
ps...I do wish there was a sarcasm emote as well as a tongue in cheek.
JN,
As I said you might want to compare overall shielded with unshielded. If only you had mastered reading.... How you can write so much... PS you might get your imagination out of the sea and let it dry off, might still be good.
Scott,
The screwball was rated the best screwdriver, the Vaco 4 in 1 flunked. Now I don't see many screwball SCREWDRIVERS anymore but lots of 4 in 1's since the patent wore out.
See I didn't even mention who I thought would prefer that screwdriver!
As I said you might want to compare overall shielded with unshielded. If only you had mastered reading.... How you can write so much... PS you might get your imagination out of the sea and let it dry off, might still be good.
Scott,
The screwball was rated the best screwdriver, the Vaco 4 in 1 flunked. Now I don't see many screwball SCREWDRIVERS anymore but lots of 4 in 1's since the patent wore out.
See I didn't even mention who I thought would prefer that screwdriver!
It's very important that you understand the test methodology behind the data Belden provides. In the audio band, with load currents far above currents consistent with the characteristic impedance of the twisted pair, there are significant differences between unshielded, shielded using the foil and drain, and shielding using woven copper or aluminum braid.
Until you understand the distinction, you will continue to waffle without understanding. The mnemonic: WWU.
Course, you really don't need to understand, as all you're doin is bog standard two conductor in a pipe. Rocket science, I tell ya!!
Simple...you're driving the bus.. that, and I've never started my drill press or lathe with the key still in...typing is not difficult..or slow.
The key is, I really do not care if you ever learn this stuff. The back and forth we engage in can be humorous, entertaining, and for anybody interested in learning new technical stuff, worth reading. I know I learn stuff here. Some of the posters here I really and truly hold in the highest regard...
Then there's you and JC...
Bada boom.
jn
JN,
Did you read the frickin data? When they wrap foil around a bunch of twisted pairs the crosstalk goes up. That would lead some to believe either that aluminum is magnetic or something else is going on. I suspect you'll go for magnetic aluminum as it is almost the same as transparent aluminum.
Now one of those things in every consultant's sound system specification is to measure the impedance of speaker lines before connecting amplifiers. Now since this is second nature to anyone with common sense, the now also ask that you record it.
Now if you have ever used the TOA ZM family impedance meter you should have noted it ain't real good below 10 ohms. So many specifications now ask for the impedance at several frequencies or to use a software/DSP based system to measure and present pretty pictures of what was measured.
As has been mentioned when you place a loudspeaker in the wind (let me know if I am going to fast for the peanut gallery) it will create a voltage. You see this as wild meter swings on an analog meter such as the TOA, but it gets well hidden in most of the other test methods.
Seeing as how it might just be important when connecting loudspeakers to amplifiers not to connect a tweeter to a woofer amplifier. (Last project it ran around $3,000.00 to change a single tweeter.) There is a simple technique to distinguish tweeters from woofers.
One would think listening would give it to you, practice says no. (I could tell about the time one consultant ((the 3" guy)) specified dual loud speakers in one box.) One front firing, one rear without an internal divider. To make things fun the rear throw was 10' and the front 75', so different circuits. The loudspeaker manufacturer labelled the terminals "A" & "B". Unfortunately calling the terminal side of the box "Left" "A" sometimes was the front and other times the back. They also had trouble with the concept of woofer and tweeter. Interestingly enough If I turned on the back circuits to see which boxes needed to be changed, virtually no one listening correctly identified the miswired loudspeakers.
So for those that haven't guessed the conclusion, ear testing is out, the way you tell woofers from tweeters is by how much the impedance meter bounces in the wind. A horn loaded tweeter makes lots more voltage than woofer!
Did you read the frickin data? When they wrap foil around a bunch of twisted pairs the crosstalk goes up. That would lead some to believe either that aluminum is magnetic or something else is going on. I suspect you'll go for magnetic aluminum as it is almost the same as transparent aluminum.
Now one of those things in every consultant's sound system specification is to measure the impedance of speaker lines before connecting amplifiers. Now since this is second nature to anyone with common sense, the now also ask that you record it.
Now if you have ever used the TOA ZM family impedance meter you should have noted it ain't real good below 10 ohms. So many specifications now ask for the impedance at several frequencies or to use a software/DSP based system to measure and present pretty pictures of what was measured.
As has been mentioned when you place a loudspeaker in the wind (let me know if I am going to fast for the peanut gallery) it will create a voltage. You see this as wild meter swings on an analog meter such as the TOA, but it gets well hidden in most of the other test methods.
Seeing as how it might just be important when connecting loudspeakers to amplifiers not to connect a tweeter to a woofer amplifier. (Last project it ran around $3,000.00 to change a single tweeter.) There is a simple technique to distinguish tweeters from woofers.
One would think listening would give it to you, practice says no. (I could tell about the time one consultant ((the 3" guy)) specified dual loud speakers in one box.) One front firing, one rear without an internal divider. To make things fun the rear throw was 10' and the front 75', so different circuits. The loudspeaker manufacturer labelled the terminals "A" & "B". Unfortunately calling the terminal side of the box "Left" "A" sometimes was the front and other times the back. They also had trouble with the concept of woofer and tweeter. Interestingly enough If I turned on the back circuits to see which boxes needed to be changed, virtually no one listening correctly identified the miswired loudspeakers.
So for those that haven't guessed the conclusion, ear testing is out, the way you tell woofers from tweeters is by how much the impedance meter bounces in the wind. A horn loaded tweeter makes lots more voltage than woofer!
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And you HAD to include me, JN! And here I was sitting in the audience with everyone else. '-)
The fascinating thing is that both Ed Simon and I do, or have done big things in audio, we are reasonably well educated, and we both have contributed to AA or AX (depending on the years). We both knew and liked Ed Dell, and his openness to audio design in general.
It just so happens that we long graduated away from SWTP amps, design a good deal of our own stuff, for both internal and for public consumption.
Now where does this leave us, in comparison to JN, who doesn't do audio, except in the most amateurish way, yet he accuses us of being a couple of 'fools'? '-)
The fascinating thing is that both Ed Simon and I do, or have done big things in audio, we are reasonably well educated, and we both have contributed to AA or AX (depending on the years). We both knew and liked Ed Dell, and his openness to audio design in general.
It just so happens that we long graduated away from SWTP amps, design a good deal of our own stuff, for both internal and for public consumption.
Now where does this leave us, in comparison to JN, who doesn't do audio, except in the most amateurish way, yet he accuses us of being a couple of 'fools'? '-)
You're putting that as a quote, yet I can't find JN saying that. Perhaps you can give me the post number?
The screwball was rated the best screwdriver, the Vaco 4 in 1 flunked. Now I don't see many screwball SCREWDRIVERS anymore but lots of 4 in 1's since the patent wore out.
See I didn't even mention who I thought would prefer that screwdriver!
Never heard of the Vaco. I generally don't read CR.
I guess you don't know what it means to put something in quotes. Try looking up "quotation mark."
se
Please. Read very carefully..
So then, we've two choices to go by here.
1. You actually pulled #10 twisted pairs that were bundled and then wrapped with a foil overwrap, then the jacket over that...to which the belden data actually applies...
or
2. You are trying (incorrectly) to use test data from twisted pair multiconductor with overall shield instead of understanding that the wires you pulled are absolutely not manufactured like that, and have absolutely nothing to do with the wires you used.
The problem with using test data which has absolutely nothing to do with what you're trying to apply it to is nonsensical, and leads to very bad and inaccurate beliefs. edit: unfortunately, I've only used #10 twisted pair cables with individual copper braid shields, even in the multiconductor runs, as we worry about hf intrusion as well as magnetic coupling.
That's what you did wrong. You need to understand the actual wire type, geometry, and what the tests really mean.
Why not both?? Seriously, the fact that you don't understand the measurements and how they apply (or not) does not mean that it's magic..
Nice to know.As has been mentioned when you place a loudspeaker in the wind (let me know if I am going to fast for the peanut gallery(don't worry, since they are reading your post, they are used to the wind.)
Gee, that one has me stumped...
Interesting. Does the voltage spectra also match the device bandwidth? edit: honestly, I'd just hook up a small monitor speaker to the amp end, and listen for highs or lows..don't need no stinkin high falutin test equipment like a "analog meter", whatever that is...
Your welcome. I know you were feeling kind of left out, I figured you were lonely..
WOW. Ed Dell.. now I'm impressed, you shoulda said so earlier...
Which of course has not contextual meaning, but you needed something to toss at me as a diss...
Glad you asked.. It leaves you in a position to absolutely have no idea what I talk about when it comes to E/M, EMC, T-line, thermal analysis, semiconductor test, soldering...the list is long. And you are left at the door, drooling because you can't even discuss it intelligently. (edit: Sorry, just hadta cash that blank check)
And yet, I already know that there are areas of expertise both of you have, that I would enjoy learning. But unfortunately, your stuck trying to assume the throne on all topics.
Never did that. You make too many assumptions.
Gee, I've been trying to figure that out for decades...
All this bickering is tiresome & childish
Why not spend you time on positive info etc ?
Actually, you are incorrect. In amongst the "bickering", which is actually simple banter, is a huge amount of technical information going back and forth. I do admit, there are a few posters who simply knee jerk with no technical input, but on the whole, there really is a good amount of info being dallied about.
jn
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Klein bought them for the screwdriver. I carry Home depots copy of it in my tool kit. You know the one that has #1 & #2 Philips and 3/16" & 1/4" flat along with a very iffy nut driver handle.
I liked them until I stabbed myself. Luckily, I have 911 on speed dial..(all nine buttons in case I only have a stump left.
jn
JN,
I have measured the crosstalk between my woofer amps and tweeter amps on site. However as mentioned wind noise makes it tough. But from a cable connected to a tweeter while music was playing the meter bounced around up to 3 volts on an analog meter. (50+ woofer amps each sourcing 500W max. into 8 ish ohms.) While wind noise is under 1/2 volt. Now the amplifier damping is going to be under 50 at midrange and above. As the particular project had run out of money and was not (and has not) paid the bill, that was more than good enough. Since then I have always had adequate shorter direct runs of conduit with enough room to keep low-high cables apart. In tray use the cables have 3' of room to themselves. But if I ever get around to it I expect to see conduit increasing crosstalk.
As the Belden data shows an increase in crosstalk from a single overall shield. I find that interesting and the basis for my feel that conduit will do the same.
Now your theory will be the exact opposite and if you ever actually do a documented measurement with NIST calibration certified equipment and publish a peer reviewed paper, I might read it.
I have measured the crosstalk between my woofer amps and tweeter amps on site. However as mentioned wind noise makes it tough. But from a cable connected to a tweeter while music was playing the meter bounced around up to 3 volts on an analog meter. (50+ woofer amps each sourcing 500W max. into 8 ish ohms.) While wind noise is under 1/2 volt. Now the amplifier damping is going to be under 50 at midrange and above. As the particular project had run out of money and was not (and has not) paid the bill, that was more than good enough. Since then I have always had adequate shorter direct runs of conduit with enough room to keep low-high cables apart. In tray use the cables have 3' of room to themselves. But if I ever get around to it I expect to see conduit increasing crosstalk.
As the Belden data shows an increase in crosstalk from a single overall shield. I find that interesting and the basis for my feel that conduit will do the same.
Now your theory will be the exact opposite and if you ever actually do a documented measurement with NIST calibration certified equipment and publish a peer reviewed paper, I might read it.
Klein Tools 70035 Magentic 4-Piece Screwdriver Set - Magnetic Screwdriver - Amazon.com
Nothing special that I haven't seen many companies make over the years. Just like a typical nut driver set with an interchangeable handle.
Nothing special that I haven't seen many companies make over the years. Just like a typical nut driver set with an interchangeable handle.
It is indeed interesting, no doubt. The problem with using multiconductor twisted pair crosstalk data is that the multiconductor cable doesn't have random pair orientations. Pulling multiple #10 twisted in a conduit can never arrange the pair to pair interaction as a production line multiconductor. In addition, conduit is generally magnetic and thick, so eddies and magfields make it very different.
I'd worry much more when the conductors are not twisted, which is more likely with AC runs in conduit.
No, not opposite. Different. It's important to use the applicable measurement data for the specific wire type and pair orientation.
Problem on two points.
1. I have no equipment which is not traceable to NIST.
2. My work papers, peer reviewed and otherwise, are not accessible to people like you.
I've on occasion, sent one or two to other posters here to get some feedback on my sanity, (blank check for ya there Ed and JC), but otherwise I can't take it outside, according to the legal types....
jn
JN,
Does that legal department prevent you from doing any published studies outside of your everyday job function? I understand that many companies hold complete control over any IP that you may have as long as you are in their employ, so I am sincerely asking if you are allowed in any way to do any published basic research? I know I have had to sign those types of NDA papers more than once with stipulated minimum amounts of years before if ever anything can be discussed or disseminated. It is a real impediment to sharing knowledge.
Does that legal department prevent you from doing any published studies outside of your everyday job function? I understand that many companies hold complete control over any IP that you may have as long as you are in their employ, so I am sincerely asking if you are allowed in any way to do any published basic research? I know I have had to sign those types of NDA papers more than once with stipulated minimum amounts of years before if ever anything can be discussed or disseminated. It is a real impediment to sharing knowledge.
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