Audio over Cat5/5e/6 cables - Page 4

they're very simple, passive devices.

Baluns refer to the transmission format change. There are dozens of different types and many are strictly passive sucgh as the 300/75 RF balun that was pictured earlier.

Transformers are wonderful devices, that is true, simple, to the point and I love em!

One audio transformer can frequently be used in place of a full bottle of Excedrin and several beers in many situations.

BTW if you look at the RF balun pictured earlier, it clearly says MATCHING TRANSFORMER.

Clearly I am and have been disagreeing with your insistence twisted pairs can only reduce noise to balanced circuits.

Again from the UTP link.


Note that there is nothing whatsoever about balanced impedances or signal types. Very very clear IMO.


I was thinking the same thing about you especially when you basically repeat what I said for two paragraphs but in an argumentative tone as if we disagreed.


Exactly what is it about my statement "I do, however, concede this point." that confuses you? The text seems simple to understand to me and rather straight forward.


The amount of noise energy recieved by the cabling depends on the conductors geometry within the noise fields. The only effect the circuits impedance has is how this energy manifests itself as noise voltage at the transciever pins. The impedance cannot somehow magically deny the noise energy entrance to the circuit. It can only vary it's resulting voltage magnitude as seen at the transciever which may or may not allow this circuit to more effectively deal with it. Denying noise energy from entering the circuit in the first place via choice of good wire geometry benefits every circuit type.

It's really great and useful that balanced circuitry deals with certain types of noise more elegantly than unbalanced circuitry but that is completely beside the point.


Could it be those examples such as where I pointed out above you spend 2 paragraphs agreeing in an argumentative way?


Grounds all have impedance which will have a voltage due to noise current travelling through it. No system has a perfect no impedance ground, not even really well designed circuits.


I'm not suprised by the idea that you can't fathom ground impedance being modulated by noise current.


It follows logically that steps to reduce it are good.

You are completely abusing that quotation. The entire reason the noise is rejected is BECAUSE it's balanced. That's the whole point I've been repeating and I cited Stephen Lampen at Belden above, which you ignore.

Since you believe that twisting a pair of conductors somehow rejects noise from external sources(other than crosstalk from neighboring pairs in a multipair cable), why don't you explain the magical principles by which this is accomplished?

Twisting the pairs doesn't do anything UNLESS it's a balanced line. Period. Stop inventing physics out of ignorance.

I'm not surprised that you'd refuse to explain this, however, I am curious to find out how current can alter the resistance, capacitive and inductive reactance of a conductor.

I am? You are the one insisting on adding words to it not in there.


The one where he mentions it won't offer common mode noise rejection like I've been saying? The problem is differential signals that these circuits are designed to respond to.


I have several times now. As I said before it's getting old repeating myself. At least I'm reading wht you write even if I disagree with some of it.


No you stop. You are the one who can't seem to come up with anything other than I said so.

Edit: You may want to investigate what a loop antenna is and what it does. I think it will help you understand what is being discussed. I already mentioned this many posts back but you seem to be having trouble reading or comprehending what has been written.

I'm not sure what is so complicated here.

An impedance with a current through it will have an associated voltage across it. You may want to check out ohms law if this seems hard to understand.

All grounds no matter how well designed have impedances built in.

me neither.


your first correct remark, bravo!


perhaps you should...show me where Ohm says that reisitance, capacitive and inductive reactance is changed by current.


You've completely avoided the question.

Tell us how impedance is modulated by current, as you previously stated.

I'm guessing that you don't know what impedance is, or what modulation means.

Ah the nitpicker approach to non-debate by attacking minor and irrelevant points.

OK einstein I get what your problem is. I probably should have said something like the noise current energy across the ground impedance modulates the voltage seen at the transciever interfaces as I explained in detail earlier. Feel better?

Excuse me for getting a little sloppy on the thousandth time we've gone back to the same idea.

Seriously man, is this the highest level of debate you offer? Kind of sad really. I guess at least you are trying to get into the technical side of the discussion now. How about an actual on topic post? That would be a hell of a step for you.

All you can do is attack...you don't understand balanced/differential signalling, and you don't seem capable of learning.
It's been explained to you numerous times yet you continue to repeat the same BS.
This is basic stuff....no need to get into the more complex stuff that you clearly won't understand until you've got the basics down.


...and we all see what yours is.


no, if you're going to pretend to be an expert, don't be sloppy....don't cry wolf either, as you often do.


And I see you've managed to stay out of all technical discussion , and offer your uninformed opinions instead

Wow, coming from you this is almost laughable.

Of course you are incorrect as usual. In my first post way back on page one I explained about the benefits of reducing loop antenna area by twisting. I don't even want to go back and count how many times I've repeated this point. None of you who is disagreeing seems willing to address this point though. There are many many attacks on me and everything I've written but none of you geniuses can put together a coherent argument regarding the actually relevant point. Lot's of blah blah blah about differential this and balanced that but only one other person has addressed the affect I have been speaking of all along and this person would seem to agree with what I'm saying based on their post.

So duvetyne why don't you explain, if you are so sure of yourself, why reducing the loop antenna effect of the signal conducting wires does not reduce the amount of noise energy injected to the circuit?

I keep asking you to do this. Of course you wont/don't even try since you obviously have nothing. What I do expect from you is more character attacks and irrelevant nitpicking. You say you are here to help but yet can't come up with a good expalnation for your POV? Seems a more than a little fishy.

You just said above that twisted pairs reject noise even if the line is not a balanced line. THAT IS NOT TRUE. If a twisted pair rejects noise in some other way than common mode noise rejection on a balanced line, please come out with it. But you can't, because you don't have a clue what you're talking about, and it doesn't.

The quote that you cited doesn't say that it does, it just makes the vague statement that twisted pairs help reject noise better, and this is true only on a balanced line, which is something that the statement did not say explicitly because it assumes that you're not an idiot and know how it is that twisting the pairs is beneficial. The way that it is beneficial is to reject common mode noise on each conductor, which is what happens with a balanced line. This doesn't happen on an unbalanced line which is why twisting the pairs is not beneficial on a balanced line which is what I've been saying since the first page.

As for your statement that "The problem is differential signals that these circuits are designed to respond to" again that is a completely nonsensical statement. The differential signals are a problem? What the heck are you talking about?



Please cite me one time you explained how an unbalanced twisted pair accomplishes noise rejection.


The wikipedia article explains it, as did Lampen from Belden, as did the article from Kurt at Blue Jeans cable.

Here are some more explanations of how a twisted pair rejects noise on a balanced line:

http://www.maxim-ic.com/appnotes.cfm/an_pk/2045

http://www.epanorama.net/documents/w...istedpair.html


I have no desire to investigate loop antennas because it isn't relevant to this topic.

duvytyne is far more blunt than I, but he is right in that clearly you haven't a damn clue what you're talking about.

Right. But that's not what you said. You claimed that voltage would change the impedance or the resistance. How this is relevant to this discussion I do not know. Small amounts of current not have any meaningful effect on this at all such as from noise which is what you mentioned.

So you said something that was completely bogus BS that you hadn't a clue about, and then you pretend that you said something else entirely which is basically an idiots version of ohms law. Nice.

That's a "little bit sloppy?" That's more like a dental hygienist who amputates your legs and goes "oh gee, you're just nitpicking I was being a little sloppy."

Hilarious. You claimed two totally BS things, one of which was that twisting conductors somehow rejects noise in an unbalanced configuration (nonsense). The other was that small noise current through a ground conductor or any conductor would change its impedance (also complete ********).

And your only explanation for these claims appears to be "read about loop antennas!"

IMO yes, especially compared to you avoiding the subject the entire conversation. I explained it first then followed up with some sloppy wording when asked repeat myself continuously. Of course you can't address the actual point of the message and keep nitpicking.


Yes as has been obvious since page one. Considering it is precisely the point I have been arguing the whole time it seems relevant. Care to address this little point? I see you are very good at finding new ways to avoid addressing this as evidenced by your repeated attempts to point out mistakes I've made in my wording.

Will Wiggles ever address the actual point or will he continue his ultra effective technique of ignoring it entirely but focusing on the irrelevant?

Edit: BTW there are many many links that tell about what happens when you form a loop with a conductor, with impedances in there. A well known phenomenon, I'm suprised you are this ignorrant of it.
Bet I know the answer...four pages later.

Do you know what irony means?

Avoiding the subject again? I'm shocked.

Question while you bicker...
How well does cat5/6 work for audio/video without baluns (or transformers)?

Pretty crappy. You get signal reflections from the impedance mismatch, and induced noise from lack of shielding.


So the answer is no, you don't know what irony means.

Avoiding the subject again? I'm shocked.

Terribly seeing as how it isn't shielded so you'll have horrible noise issues if there's noise in the environment, and for digital audio and video where impedance is a concern you'll get reflections which are no good either.

It can be done though, I've done it before, with the expected bad results. But if that's all you have there, and no baluns...

I missed you making any kind of a point in that message, or really in any other message in this thread.



No I won't adresss this point because: 1) you haven't made a point 2) twisting the conductors together doesn't change anything about how they may act as an antenna and 3) you're a fool.



WHAT POINT!? What the f**k are you talking about!? WHAT link?

If you have a point, COME OUT WITH IT. If not, bugger off, twisting the conductors together doesn't make a damn bit of difference unless the line is balanced. This is a completely noncontroversial statement, and if you're too stupid, ignorant, and stubborn to recognize it, then I'm not going to waste my time with your idiotic claims about loop antennas which have nothing to do with anything.

Your lack of reading comprehension skills is very apparent at this point. From my first post in this thread, post #5:

"The act of twisting the wires extremely reduces the current loop areas (read reduce antenna efficiency) and does wonders for detuning these cables to the ability to resonate (form standing waves) in the presence local ambient EMI noise field energy."

I've repeated this smae idea numerous times to you now. Keep avoiding the subject.


1. clearly the point has been made by me and others numerous times, lord knows why you haven't noticed or keep trying to avoid it 2. anybody who knows anything about loop antennae knows that decreasing loop area is proportional to it's gain 3. you are the fool and are now acting like a jerk too.


The one that has been made many times by me now and also others in this thread. You might try google.

heres a good place to start


Again? Really, come on. I've already repeated myself too many times to even bother counting. Yours is clearly a lost cause since you seem to be under the impression you know everything but unfortunately stopped learning well short of the mark necessary to speak of these things.

------------

Please check off the answers that apply from the following list:

(1) I never took a course in transmission lines in college, so my lack of proper understanding of twisted pair transmission lines is understandable.

(2) I have never done any significant projects with transmission lines, so my lack of proper understanding of twisted pair transmission lines is understandable.

(3) I don't know how to search google for articles about how transmission lines work, so my proper understanding of twisted pair transmission lines is understandable.

----------

Just in case my lame attempt of humor somehow flies over your head or under your feet...

The area inside a loop of wire strongly determines how it works as an antenna or secondary of a transformer.

One of the benefits of twisted pair is that like coax construction, it goes a long way towards reducing the area inside the loop until it is vanishling small.

The line need not be balanced for twisting the wires to be very helpful when it comes to picking up interferance from external sources. Since the power lines in your home and business are not intentionally desighed to be coax or twisted pair, they radiate wonderful magnetic fields and are very willing to act as the primary of a transformer.

First, Chris is right about balanced lines where NEITHER line of the balanced pair is tied to signal common as the only definition of a balanced signal line, by the very definition of the term balanced. The other option is unbalanced where by definition and circuit design, the signal is tied on one side of the path to signal common.

I would love to have seen one single example of an audio or video device that uses a single ended I/O connection and refers to it as balanced.

It is either balanced with no signal ground connection in order to function or unbalanced with signal ground as the return.

No gray area. No noise cancellation is possible with a UTP configured as a single ended xmission line with one phase and one signal common connection. This is precisely why shielding on single ended circuits is so important and why the best shielding fully encompassed the phase conductor in a foil or tightly braided wrap. If any part of the phase conductor is not shielded as would be the case in a UTP configured as an unbalanced xmission line, noise can easily take advantage of the "antenna effect".

This is precisely why cheaply made shielded cables with loose or non-uniform and tightly constructed shields can go "microphonic". In video, you end up with ghosting and other artifacts.

If someone wishes to refute this in a real manner, post the device Manufacturer and model so that we all may revel in the magic of such a device.

We should then contact all the shielded wire and XLR manufacturers, and transformer manufacturers and thank them for years of dedicated service but it has been determined here that the physics applied to the electronics industry and AV in particular for the last 80 years have been in error. We will no longer be needing their services.

And then you woke up.

Agreed.


Disagreed.

One can unravel a twisted pair and form the two conductors into the shape of a circular loop. The bigger the loop the more frequencies it can recieve, and the more efficiently it will do so. This configuration is guaranteed to recieve more noise from ambient noise fields of the correct orientation and frequencies that the loop is tuned to as compared to when the conductors were twisted together. Twisting the pairs minimizes loop area of any potential antennae, thus detuning them to potential noise sources by reducing the range of frequencies the loop can physically recieve and the sensitivity to the field strength of potential noise sources by reducing gain.

The impedance of the circuit does not affect antenna gain or the frequencies it may recieve. The impedance only affects how the noise energy current manifests itself as a voltage where it counts: usually the recieve end but if these voltages end up being large enough active electronic transmitters can certainly be affected negatively as well. The impedance presented by the loads and sources and even the lines themselves determine whether the antenna has a balanced impedance which determines the fidelity of the recieved signal. True that an unbalanced antenna could not be used for high fidelity radio work, but who cares in this case? The question is whether the noise is there at all, not if it is distorted.

In summary: the circuits geometry is related to it's effectivity as an antenna by determining it's frequency response and field sensitivity. Its distributed impedance characteristics determines the fidelity of any recieved signal/s.

Edit:


Who said anything about shielding not being effective or having it's place?

No matter how tightly you twist a pair of wires, there is no resultant drop in inducted noise on that line IF the line is configured as single ended I/O. There is essentially no area of the phase wire that is not exposed.

Before the development and use of balancing transformers for microphones. the standing rule of thumb for mic cable length from the mic element itself to the control apparatus was 30 ft. Much past 30 ft and there was a plethora of noise and radio reception etc that was easily picked up on unbalanced cables due to the antenna effect. The advent of fully balanced cables and transformers eliminated that problem.

Today's mic elements are still single ended with respect to the phase and signal common, but the xmission lines are balanced. Problem solved.

I have run base band video and audio over standard mic cables and UTP premise wiring using active and passive baluns from floor to floor and between buildings for hundreds of feet with no problems at all.

Not possible to do that with UTP wiring connected as a single ended (common/phase) wiring configuration no matter what the twist is.

I don't doubt it one bit. No one is saying balanced lines don't help with noise problems.

The relevant point here is that twisted or tightly spaced parallel wires got you to the 30 foot limit you mention. Unravelling and maximizing loop area would have reduced the limit even further than thirty feet in high noise environements. The fact that most of us are running unbalanced single ended setups with no transformers etc means this twisting is relevant to these systems in a big way.

I just twisted my telephone wire (RJ11) and now I hear a radio station on my phone!

C'mon baby! Let's do the twist...

The cables used were single ended, spiral wrapped shielded cables. Identical in design to the cheap little RCA cables of today. Once the concept of transformers balancing the lines and extending the usable cable lengthwas understood and accepted, 3 pin ITT /Cannon connectors (precursor to XLRs of today) were used. The pin configuration was the same as today, albeit much larger.

Transformers were incorporated in the microphone housing and added to existing audio equipment. This allowed the close proximity of several cables of similar and different source material.

I have seen a few times over my rather long career where someone TRIED the TP concept for a single ended I/O but it never works. in the real world.

BTW I grew up in the AV industry from the early 60's and my dad put several TV stations on the air including the ABC station in DC WJAL formerly WMAL and four other TV stations in Fort Wayne, Indiana, and Parkersburg, WV.

I have seen and worked with the evolution of sound systems and cabling for many years all over the country, so I have been intimately involved with this for many moons.