Can ethernet, coax, speaker wires share stud-holes with power cables behind wall?

[Howard]

Regardless if there is a lot of EMI or not runs more than 2 meters benefit greatly by going to balanced lines.

How so?

 

[spidey07]

How so?

Noise floor. Why it's ideal to use balanced to mono blocks by speakers.

 

[NL5]

How so?

Balanced lines reverse the polarity of one line, then switch it back at the other end. Any stray interference will be picked up by both lines, and cancelled out when switched back. Like Ruby said, it's better for runs of any length over about 8-10 feet. Unbalanced is best for signal integrity, but interference outweighs in longer runs.

 

[iGas]

Code do not allow low voltage to be running through the same hole or conduit as other cables unless they are all are low voltage cables.

Industrial/commercial tend to call for 12" separation between Ethernet and power cables and/or heat pipes in parallel.

I believe that you can run Ethernet cables as close as you can in parallel to house hold electrical wiring as long as there is an air separation/gap or inside conduits.

 

[The Boston Dangler]

Does anyone know if I'm required to run a separate ground to a grounding rod? Or is connecting it to the ground on the main breaker panel sufficient?

ground it to the house's panel - it's easier, cheaper, and there's no ground loop.

 

[PsiStar]

Balanced lines, aka differential lines, are most immune to common mode noise which is the dominant means of interference getting into systems. Common mode means that the noise is near equal level on both of the balanced lines.

Most homes probably do not have much EMI because all of the wires are thrown on the floor behind the cabinet holding the components. When a house gets "wired" for everything as Doppel is doing, then a little planning is in order to control the radiation from all of those long runs of copper. And they *will* radiate some thing. Not only from what is inside the shield but from other signals floating around.

 

[Howard]

Balanced lines reverse the polarity of one line, then switch it back at the other end. Any stray interference will be picked up by both lines, and cancelled out when switched back. Like Ruby said, it's better for runs of any length over about 8-10 feet. Unbalanced is best for signal integrity, but interference outweighs in longer runs.

Balanced actually doesn't mean reversed polarity, you just need the same impedance on both lines for the common mode noise to be canceled.

As for signal integrity, there's no reason for either balanced or unbalanced to be better.

 

[Modelworks]

The NEC is concerned with safety not noise or interference. You cannot bundle power lines and low voltage wiring inside the same channels without a barrier separating them . The reason for the rule is that power lines typically have a 600Volt insulation rating and cat2 and 3 low voltage wires like speaker wires usually have an insulation rating much lower, typically 50 volts. If a power wire connection were to contact the outer insulation of the speaker wire, the dielectric will break down and now you have a speaker wire that should be low voltage carrying power line voltages.

The exception is if the wires you are using have the required insulation rating. Generally you want all the wires in the channel to have the minimum insulation ratings for the largest load in the channel.

 

[Modelworks]

Incidentally, I'm putting in a 100Amp breaker panel in the garage. The garage is attached to the house. Does anyone know if I'm required to run a separate ground to a grounding rod? Or is connecting it to the ground on the main breaker panel sufficient?

You need a ground wire run from the main service ground to the sub panel. The wire size for 100amp needs to be 6AWG aluminum or 8AWG copper for the ground connections.

 

[NL5]

Balanced actually doesn't mean reversed polarity, you just need the same impedance on both lines for the common mode noise to be canceled.

As for signal integrity, there's no reason for either balanced or unbalanced to be better.

Actually, you're wrong on both counts. One line in a balanced cable has the polarity reversed.

This guy does a pretty good job of explaining it, and he also touches on the fact that unbalanced is superior.

http://www.audioforums.com/forums/s...lanced-Stereo-what-are-they&p=93196#post93196

In the pro audio world (where I come from) a lot of the time, we actually want the signal degradation, as it adds pleasing harmonics. I run balanced on some small runs to get that distortion.

 

[Howard]

Actually, you're wrong on both counts. One line in a balanced cable has the polarity reversed.

This guy does a pretty good job of explaining it, and he also touches on the fact that unbalanced is superior.

http://www.audioforums.com/forums/s...lanced-Stereo-what-are-they&p=93196#post93196

In the pro audio world (where I come from) a lot of the time, we actually want the signal degradation, as it adds pleasing harmonics. I run balanced on some small runs to get that distortion.

http://sound.westhost.com/project87.htm

Scroll down to "Hey! That's Cheating".

Now, as for the last thing you said: that's one of the dumbest things I've heard in my life. First of all, you haven't even shown how transmitting/receiving a balanced line is any worse than an unbalanced. Second, there's no way that balanced could add any appreciable harmonic distortion (Ed: at least with well-designed equipment). Third, even if you did want "pleasing harmonics", you'd install a device that was meant for doing that so that you could actually control the amount of distortion to add.

More info if you'll take wikipedia as a source: http://en.wikipedia.org/wiki/Balanced_line

 

[NL5]

http://sound.westhost.com/project87.htm

Scroll down to "Hey! That's Cheating".

Now, as for the last thing you said: that's one of the dumbest things I've heard in my life. First of all, you haven't even shown how transmitting/receiving a balanced line is any worse than an unbalanced. Second, there's no way that balanced could add any appreciable harmonic distortion (Ed: at least with well-designed equipment). Third, even if you did want "pleasing harmonics", you'd install a device that was meant for doing that so that you could actually control the amount of distortion to add.

More info if you'll take wikipedia as a source: http://en.wikipedia.org/wiki/Balanced_line

From the Wiki article you cited -

"These signal wires carry two copies of the same signal, but with opposite polarity"

Kinda what I was trying to say.

As far as distortion. Every single piece of pro audio I've ever seen, and that is literally thousands, uses a balanced output transformer. Which there are endless debates about the merits of the various cores, windings, and what-not's, but they all add a distortion. Especially when driven to saturation. Like Rubycon pointed out, when you get to high end mastering gear, they almost never use a balanced connection, as their #1 goal is to NOT color the signal. They want as close to perfect as possible. Therefore they don't use an output transformer, and cannot send a balanced signal. It's a cleaner mode of transfer, but there is no way to get rid of any interference. Again, this is why balanced becomes a better option past 10 feet give or take.

In pro audio, distortion is king when your at the production/recording stages. I know that may seem counter-intuitive, but it really is. Heck, there are tons of gear that are designed for that SOLE purpose.

 

[Howard]

From the Wiki article you cited -

"These signal wires carry two copies of the same signal, but with opposite polarity"

Kinda what I was trying to say.

I'm not sure what that was but it wasn't what I was trying to say. I wasn't referring to industry practice, but instead what was necessary to eliminate common mode noise, and again I repeat, the impedance just needs to be the same.

As far as distortion. Every single piece of pro audio I've ever seen, and that is literally thousands, uses a balanced output transformer. Which there are endless debates about the merits of the various cores, windings, and what-not's, but they all add a distortion. Especially when driven to saturation. Like Rubycon pointed out, when you get to high end mastering gear, they almost never use a balanced connection, as their #1 goal is to NOT color the signal. They want as close to perfect as possible. Therefore they don't use an output transformer, and cannot send a balanced signal. It's a cleaner mode of transfer, but there is no way to get rid of any interference. Again, this is why balanced becomes a better option past 10 feet give or take.

How much distortion is added by an output transformer? More than http://www.jensen-transformers.com/ln_out.html Depending on how much, I'd agree with you.

Still, I don't know why so much gear would use transformers when op-amps are so much cheaper and cleaner.

 

[NL5]

I'm not sure what that was but it wasn't what I was trying to say. I wasn't referring to industry practice, but instead what was necessary to eliminate common mode noise, and again I repeat, the impedance just needs to be the same.

Wow. I don't know how to make it any clearer. Yes, Impedance needs to be the same, but that is not what is used for rejection. It ensures that the interference is induced equally into both signal wires. If you take a signal (waveform), split it in two, reverse the polarity on one, then send them down two equal wires (matching impedance), when they get to the other end, they will have had the exact same interference added. Now, when you switch the polarity back at the other end, the interference will be polarity reversed, and when the signal is added back together the two interference waves will null, and the original signal will be unaffected. (except for the added distortion from the balancing/unbalancing)

Still, I don't know why so much gear would use transformers when op-amps are so much cheaper and cleaner.

You have a lot to learn about pro audio. Cheaper. LOL.

 

[Howard]

Wow. I don't know how to make it any clearer. Yes, Impedance needs to be the same, but that is not what is used for rejection.

Yes it is. Are you saying that if the signal is not the same on both lines, the induced noise from EMI will not be the same on both lines as well? Why do you suppose the wires in signal cable for balanced transmission are always twisted?

You have a lot to learn about pro audio. Cheaper. LOL.

What's the cost of a typical output transformer used in pro gear?

 

[Rubycon]

Since Jensen Transformers was previously mentioned you're probably familiar with Bill Whitlock.

Check out this article written by Bill at the PSW Study Hall:

http://www.prosoundweb.com/article/the_truth_about_balanced_audio_interfaces/P2/

If you want good material to read up this place is THE place to go. Their forums are unmatched and there's a lot of familiar names there in the field.

 

[NL5]

Yes it is. Are you saying that if the signal is not the same on both lines, the induced noise from EMI will not be the same on both lines as well? Why do you suppose the wires in signal cable for balanced transmission are always twisted?

I'm not really sure what you are saying. The signal in the line has nothing to do with the interference.

Here is a pretty good explanation of why the wires are twisted - and again the article reiterates that the signals are polarity reversed, and then back again -

http://en.wikipedia.org/wiki/Twisted_pair

As far as transformers, they can be hundreds of dollars. I haven't bought one separately in a long while, and even then I was looking for vintage Neve transformers, which are one of the more expensive ones depending on which one you're looking for

 

[Doppel]

Some very helpful responses! Grabbed some in wall rated speaker wire today to get going. I don't need to worry about the finer details of wiring since this is never going to be hooked up to high end equipment, but I will be sure to be quite liberal with spacing of all data and av lines.

 

[Howard]

I'm not really sure what you are saying. The signal in the line has nothing to do with the interference.

Here is a pretty good explanation of why the wires are twisted - and again the article reiterates that the signals are polarity reversed, and then back again -

http://en.wikipedia.org/wiki/Twisted_pair

As far as transformers, they can be hundreds of dollars. I haven't bought one separately in a long while, and even then I was looking for vintage Neve transformers, which are one of the more expensive ones depending on which one you're looking for

http://en.wikipedia.org/wiki/Differential_signaling

This advantage is not actually due to differential signaling itself, but to the common practice of transmitting differential signals on balanced lines.[1][2] Single-ended signals are still resistant to interference if the lines are balanced and terminated by a differential amplifier. See Balanced line for more details.

http://en.wikipedia.org/wiki/Balanced_line

Circuits driving balanced lines must themselves be balanced to maintain the benefits of balance. This may be achieved by differential signaling, transformer coupling or by merely balancing the impedance in each conductor.

Lines carrying symmetrical signals (those with equal but opposite voltages to ground on each leg) are often referred to as balanced, but this is an entirely different meaning. The two conditions are not related.

Since the receiver responds only to the difference between the wires*, it is not influenced by the induced noise voltage.

*A-(-A) = 2A, but A-0 = A (the only difference is half the gain)

http://sound.westhost.com/project87.htm#cheat

Now, before you get all horrified, let's have a proper look at what is happening. The main trick with a balanced circuit is that the receiver should "see" the same impedance on each input. It doesn't actually care that much if there is signal on either or both wires (indeed, that is merely an expectation on our part), but even if the wanted signal is only on one wire, any induced noise will still be common mode, and will still be in phase across both wires. The noise gets cancelled either way, and the signal gets amplified, which is just what we want.

Yes, it's cheating - but it works. Apparently, this trick is used on some of the popular stage mixers, as well as some very well regarded phantom feed microphones (although as far as I know they don't use the Zobel network - this is optional BTW). There is less signal than one would expect (most balanced transmitter circuits have an effective gain of 6dB), but this is generally not an issue. In the case of a microphone, the signal is the same as it would normally be anyway, and with a line output, 6dB of additional gain is usually not a problem to achieve. The amplifier as shown in Figure 4 only needs 2 x 10k resistors in the feedback path to achieve this (10k from output to -ve input (i.e. -in, not -ve supply pin), and 10k from -ve input to ground).

In most cases, this will work just as well as a true balanced output circuit, for the simple reason that it is a true balanced circuit. From the perspective of the balanced input circuit (the receiver), this arrangement provides exactly the same signal quality as if the circuit were fully (signal) balanced, but the signal is -6dB compared to a circuit with a balanced signal.

 

[NL5]

http://en.wikipedia.org/wiki/Differential_signaling



http://en.wikipedia.org/wiki/Balanced_line



*A-(-A) = 2A, but A-0 = A (the only difference is half the gain)

If I am understanding you correctly, you are saying that you could have a balanced line where a signal is sent down just one line, and then when the signal gets to the other end, the un-signaled (0V) line is polarity reversed and used to cancel out the interference?


I can imagine that that would work, but it's simply not how it's done with audio - and I do see where the last quote is saying that is what the circuit is doing, but it is still reversing the polarity to accomplish the rejection. You just lose 6db, which in the audio world is a bad thing for your noise floor.

Here's maybe a better explanation - http://www.mediacollege.com/audio/balanced/cable-balanced.html

It seems as though you are trying to cut out bit's and pieces without understanding what is going on. Every link you've cited has said they are sent with polarity flipped, then flipped back at the other end.

Also, as far as the quote saying that symmetrical signals sent out of phase is not the same as balanced line, that is correct. My studio is run that way for power. Most power in the US (non industrial) is run with a hot leg, and a neutral (0V). All 120V power in my studio has two "balanced" legs at 60V 180 degrees out of phase. It's not the same as what we have been discussing, as the polarity is never flipped. It's actually to cancel out interference being generated - just the opposite of what all the audio ties are doing.

Although a resi panel is actually two 120V legs 180 out of phase, so I guess we do use a some "balanced" power for 240V loads.

Anyway, we are way off topic. I'm glad the OP decided to run things the way they are supposed to be - I'm sure he'll be happier with the results.

 

[Howard]

If I am understanding you correctly, you are saying that you could have a balanced line where a signal is sent down just one line, and then when the signal gets to the other end, the un-signaled (0V) line is polarity reversed and used to cancel out the interference?

What do you get when you "reverse the polarity" of 0 volts? Nothing. The output from the balanced receiver will simply be what the balanced cable delivered, minus whatever is common to both hot and cold lines, which would result in the signal minus most of the noise.

Why do you keep linking to random web pages that say that balanced connections run the same signal on two lines but with one inverted? I already told you that I understand this is industry practice so please stop belaboring this point.

I am not adequately learned enough (or rather, I forgot all my electronics teachings) to debate whether differential signaling offers a real 6 dB noise- and distortion-free gain over single-ended balanced, but I would ask this: is a single-ended balanced signal attenuated by the line driver and/or receiver, or does a differential signal actually get amplified in the line driver and/or receiver? I believe it's the latter for electronic balancing, in which case using differential signaling offers no better noise performance.