Bob, is it that balanced "twists" the wires over so that any interference hitting the looooong length of cable gets, well, erased 'cos the wires have been crossed over? Soooo any external EMF inducted into XLR cabling is removed OR "balanced-out" when the signal gets to the RX end - gets reduced to zero? - Apologies for the slack use of words.

Grazie

No, the twist does help but mostly on really ling cable runs.
What goes on is this. The signals are 180 degrees out of phase and in a genuine balanced circuit are not referenced to earth. Now any noise induced in the cable will be the same in both wires i.e. in phase and better still referenced to earth.
So if we invert one wire and add it to the other one the signal we dont want is cancelled out, the one we do want is unaffected.
Thats one way to look at it.
In the good old days of real audio all this was done using quite expensive transformers. These ensured that a balanced output was truly isolated from everything in the device sending the signal and as there was another transformer at the receiving end again no connection existed for earths etc. In fact for telecommunications circuits these transformers had to withstand either 2000 V or 5000 V, they were really isolated! This is pretty much how the audio in the telephone system can go many miles with 100s of circuits in the one cable and get very little hum or crosstalk.
These days very few audio devices use transformers as they're just too expensive. Balanced drivers and differntials amplifiers are used instead. As much as these have improved they're still not as good as transformers. They do have limitations in their maximum common mode voltage of around 15 to 30 volts. If you manage to get EMI at that level you'll still get breakthrough.

One thing that bugs me a bit about all this. The common advice is that balanced audio is better. I beg to differ. For certain gear that uses balanced circuits is generally better designed and built. Yes balanced low impedance ciruits have lower HF loss than hi impedance unbalanced lines over long distances.

However all the differential amps and line drivers are more stages in the circuit. That's more noise, more slew rate limitations and more distortion etc.
A small point I suppose and you'd have to be a fanatic to hear the difference although I did hear of one guy who ripped all the balanced circuits out of his studio, put the whole thing in a Faraday cage and figured he'd removed 18 stages in the signal path and yes you could hear the difference.

Bob.

No Bob . . my ""twists" the wires over " was my way of explaning your far more technically lucid, "So if we invert one wire and add it to the other one the signal we dont want is cancelled out" . . . I wasn't thinking of the "caging" of twisted wires . . .

.. in any case, wires crossed here! No harm done! :)

Grazie

Seems like we had our wires crossed :)

From the old telephone days, the term was "twisted pair", so, not only are our wires crossed, but we're all twisted as well.

Ah! Yes good old GPO! - Twisted Pairs! G

"One thing that bugs me a bit about all this. The common advice is that balanced audio is better. I beg to differ."

Bob, you're talkin out your ass and while some of your information posted is correct, a lot of if is also wrong.

"Bob, you're talkin out your..."

WOW, Bob, you've got quite the talent there. i bet you could be famous if you just figured out some way to not moon everyone if showed off your tallent.

BTW, Red, I think in this case his rear was typing, not talking. (unless he was using voice recognition software - did you have to get a different one to understand your rear?)

Dave

Problem solved.

In the late 19th century there was a Frenchman who was travelling the world with a four foot rubber hose hooked up to a funnel used to broadcast the sound to the paying audience in front of him.

No nudity, he just inserted the non-funnel rubber hose end into his own, with his pants on of course, and proceeded, not to speak, but to play the Marseillaise, the Star Spangled Banner and popular requests from the audience (perhaps Rimskij-Korsakov's "The Flight of the Bumble Bee", which was written around that time).

Which brings me back to the cables. You may have heard that it has been scientifically proven that bumblebees can't fly. They are too heavy and their wings are too small. The good thing is that they don't know this (and nobody wants to admit being the source of the bumblebee flight calculation which assumed a rigid wing...).

The bad thing is that people still look at currently available measurements and conclude that all cables sound the same. Instead of listening to see if they do.

Why is it called "common sense" when it isn't common?

Perhaps Red would care to illuminate us as to how introducing additional stages into an audio ciruit improves the situation?
I never said that an unbalanced circuit has less immunity to EMI, simply that adding additional stages into the audio path doesn't improve the signal. That would seem to be common sense as opposed to common knowledge.
Bob.

I have to agree with Bob's statement that balanced isn't necessarily better, and for the exact reason he gives.

Common mode rejection is nice to have for those of us not working in a Faraday's cage, but it is certainly true that having extra stages often screws up the sound.

A long time ago I built a RIAA+line preamp that blew people away with its sound quality. Secret? Minimalist design (not balanced by the way).

Fewer but better designed stages leads to better sound quality at a lower price.

In a studio, or on location in a noisy environment you may need balanced audio though, no matter what it does to the quality of the underlying audio signal.

Back to post 1 above. The unbalanced 1/8" minijack is probably for a stereo cable to a mini-DV camera, so it would feed both tracks.

Please don't get me wrong, I'm not suggesting we start running unbalanced mic lines all over the place!
Bob.

What does your camera have for mic input?
What camera model?

If your camera has XLR inputs use the balanced port on the wireless.

If your camera is a consumer model with 1/8" jack it might be a stereo
mic input and supllies a very small voltage to power the external stereo mic.
(this is a bias voltage not phantom power)
You will need an adapter cable made, don't use a stereo headphone
adapter as it may short out the cameras mic circuit. You will most likely
plug into the unbalanced port 1/4" jack.

The balanced port will most likely be mic level while 1/4" may be
line level. Contact the wireless manufacturer for a cable recommendation.

As far as balancing in the editor, you will be on either the left or right
channel and you can use pan adjustment.

The problem here is that everyone has a different idea of what "Good" audio is. The moment sound enteres a microphone (Actually before it enter's the microphone ,due to the acoustic environment) the sound gets messed up. A great deal of the work performed by the audio chain and audio engineer is an attempt to make the sound sound like what it should have in the first place, before it was converted into to electricity. The volume is increased, the frequencies are equalized, noise is cancelled out or removed... etc. etc. Whenever a "compensation" is made to make the sound "better", some sort of change to the signal is introduced some intended, some not intended, which, it could be argued, makes the sound "worse".

When you consider that each one of us hears sound differently, and has different expectations of what something "should" sound like, the entire process of determining what is "good" or "bad" audio becomes extremely subjective and horribly complex.

For instance, whenever I enter a recording studio to work, I've found that the studio's choice of monitor speakers can tell me something about the recording engineer, or the person who specified the speakers. i.e., If they're using Yamahas, the engineer worked with rock bands for a while and is now somewhat deaf.

Transformers do degrade the signal somewhat -- they have trouble passing the high-highs and low, lows -- however, they warm up the audio a bit, some add odd-order hamronics, which can greatly "improve" any audio which is digitized at lower than 70kHz. Is that "good?" Is that "bad?" Depends on personal taste. They also mess with signal phasing, which many audio engineers claim they can hear, despite the fact that study after study shows that human beings can't hear phase changes. (I don't care what the studies say, I CAN hear phase changes... The question for me is, is it bettor or wose.)

Travis
Travis Voice-Over Narration Services
www.Announcing.biz

Well, you guys seem to be overlooking a few very important factors of Balanced circuit operation. I'm not even worried about EMI susceptability, let's go onto the circuit board where all these amplifier stages are taking place.

In a circuit where a balanced operation is maintained throughout the signal path the noise generated by the actual opamps in that circuit also gets reduced due to the common mode rejection aspect of the circuit. Every amplifier stage has a noise floor correct? Well in a balanced circuit this noise floor becomes "Common" and therefore get's drastically reduced. So where the output is generating the noise floor, the next amplifier stage's input is elliminating it through the common mode rejection. Now in an unbalanced circuit it still has a noise floor. The way to try and reduce this noise floor is through using RC filters on the outputs and inputs. What do capacitors do to your signal? Capacitors add phase distortion problems. So in a balanced circuit these capacitors can be elliminated allowing the original signals phase qualities to stay intact. So you're actually able to reduce the components in signal path in a balanced circuit and not introduce phase distortion problems.

Another part to look at is the specifications of unbalanced line levels vs. Balanced line level signals used in actual equipment. Balanced signal levels will generally be +6dB to +14dB higher in level. So now do you not only have a common mode rejection working for you for EMI noise rejection, but you also have less concern of running long wire runs where the wire impedance becomes a factor in the S/N ratio.

This is also the digital age where the majority of equipment uses A/D and D/A converters in the signal path. Have you ever looked at the audio signals output of a D/A converter with an O'scope? You will see it's pretty much undistinquishable among all the noise generated by the DAC's due to all the high frequency switching. Do you know how they elliminate the DAC noise coming out of an unbalanced DAC? A series of RC filters again followed by the amplifier stage. Do you know how it's elliinated when a Balanced DAC is used? They let it ride right out into the balanced amp stage, where it's elliminated through the common mode rejection again. So again less circuits in the signal path.

So I'm not sure where all these extra amplifier stages are being created in your circuits for a balanced circuit, I only count 1 additional opamp for each amp stage so that the signal is being inverted for one part of the equation. Infact in most unbalanced designs they use inverting opamps where they abide by the equation of the resistors connected to them of GAIN=-R2/R1, which means they have to put another opamp directly behind it where R2=R1 and therefore has a unity gain, but is there only to put your audio signal back in phase. In a balance circuit you don't need to do that because you're reversing the phase of both amp stages therefore you just switch your positive and negative terminals feading your outputs. No additonal amp stage needed to invert the phase. The last time I checked the equation for a non inverting opamp was still "Gain= 1+(R2/R1)", meaning you can't attenuate the signal, unless you use a voltage divider before the amp stage, and then that adds another noise factor contribution.

You guys want to talk amplifiers along with balanced vs unbalanced circuits, I'm here all week. I just happen to design them for a living, and could probably talk for days on the subject plus have a few dozen electrical engineers sitting near me who do the same, that just might want to jump in on the subject for a few laughs.

The funny part to me is the only one that seemed to address the original question was Rcourtney in his above reply. Which is probably the correct answer, where it depends on what kind of input his camera has and it has nothing to do with "Balance" in the way the original person asking the question thought it to be.

I addressed the original question in my 1:24pm reply.

"some add odd-order hamronics, which can greatly "improve" any audio which is digitized at lower than 70kHz"

Odd-order harmonics usually sound good only to techno lovers. The rest of us tend to prefer even harmonics.

I addressed the original question in my 1:24pm reply.

I don't see that you did actually. While Red, Bob and yourself offered very accurate, for the most part, detailed info concerning "common mode rejection", it's advantages and disadvantages I don't see how you blanketly answered the question.

The OP's question was:

I just got a Gemini UHF wireless dual mic setup. The back of the receiver has two XLR male plugs and under them it says 'balanced'. Next to the XLR plugs is a 1/4" female plug for an out to my camcorder...it says 'unbalanced' under it.

Your 1:24pm answer;

Back to post 1 above. The unbalanced 1/8" minijack is probably for a stereo cable to a mini-DV camera, so it would feed both tracks.

If we all cut to the chase... all of you have described the physics of this and it's pro's and con's but cutting through all the technical jargon for most everyone else here, I think the answer really is that if you have long run environments or environments where noise is a problem whether it be AC, RFI, whatever, balanced is the way to go.

That said, having balanced options with your gear as apposed to not... is a major advantage. Add to that... as Red said most balanced devices are at least 6 dB hotter than un-balanced making balanced more desirable in all environments when signal to noise is factored in.

Even more bottom line... if you have gear that supports balanced connections... you would be amiss to not use them with balanced cables.

MJ

Red,
everything you're saying is 100% correct, certainly if you keep everything balanced the whole way through you're miles in front.
Question is though is all audio gear designed like that?
I've seen a lot of designs that don't even look to me as though the inputs are all that exactly balanced.
You'll have to excuse my ignorance on this point, it's been a while since I've delved deeply into this stuff, the last time I did, we for example fed phantom power through the CT of a transformer and fished it out at the other end the same way. You could switch the phantom power on and off and not get the slightest blip in your audio, today you do that and all hell can break loose which says to me something is unbalanced.

Can I raise another point that perhaps doesn't get enough consideration. Just because an audio connection uses XLR connectors doesn't mean it's a balanced circuit, a lot of the B'ringer mixers have outputs on XLRs but they're not balanced.

Bob.

Coursedesign said:
"Odd-order harmonics usually sound good only to techno lovers. The rest of us tend to prefer even harmonics."

Sorry, I've seen to have missed something there. We're talking the difference between unbalanced and balanced circuits. Now how does this somehow jump us over to odd and even harmonics? Somehow, you're way off track with your information. Let me help you get back on track as far as adding odd or even harmonics. There's been lots of studies on "distortion" of why people like tube distortion and not transistor distortion. It was found that tubes tend to produce more even harmonics when they distort the signal, whereas transistors add more odd harmonics. Thus the conclusion that even harmonic distortion is more desireable to the human ear. Now if you can tell me how this somehow ties in with the balanced/unbalanced debate we're having here, I'll somehow be enlightened. Point is I haven't heard anything from you supporting your unbalanced is better viewpoint.

"certainly if you keep everything balanced the whole way through you're miles in front.
Question is though is all audio gear designed like that?"

Oh course not. Lots of gear internally is a combination of both. Why? To save on the cost of course. When people buy gear they see "supports 24bit/192Khz sample rates". Thus it has Codecs that have a bit debt of 24bits and a 192Khz sample rate. Great, well the unbalanced 24/192 codec costs $1.25, while the balanced 24/192 codec costs $3.75...3 times the cost. Yet, guess which one has the better signal to noise ratio made by the same chip manufacturer? It comes down to you get what you pay for. That's why you can buy an Art Reverb unit for $125 with balanced I/O, while you pay $1125 for a Lexicon reverb.

You give me the same opamps and I design one amplifier that is unbalanced throughout the signal chain, and another amplifier that is balanced throughout the signal chain, which one has the lowest noise floor at the end of the day? Hands down it will be the balanced design.

MJhiq,

When I replied at 1:24pm, there had already been a number of posts explaining balanced vs. unbalanced, so I addressed what I thought was the first poster's concern: "how do I hook up this wireless receiver to my camera?" I told him that the unbalanced connector was probably meant for a stereo cable to a stereo input on a consumer camcorder.

Of course if you have balanced gear, you use balanced cables. The problem for most consumers is when they have a mix of balanced and unbalanced gear.

There is a huge number of situations that are affected by equipment and wiring choices. I think I could talk about that for a couple of days full time at least, just based on my own 38 years of experience in audio engineering.

MJhiq, you need to relax a bit and realize that there are people out there with consumer cameras and they may need to do things a little bit differently.

I used to shoot training videos with a TRV900 at one time. This camera doesn't have balanced inputs, but I was able to run a [high quality] microphone cable across the room, under fluorescent fixtures, with no interference or noise problems whatsoever. I had no other option at that time.

Today I shoot only with a high end broadcast camera, and of course it doesn't even have any unbalanced inputs.

Rednroll,

I wasn't responding to your post when I was describing the difference between even and odd harmonics.

I was referring to ttravis's post that said "Transformers do degrade the signal somewhat -- they have trouble passing the high-highs and low, lows -- however, they warm up the audio a bit, some add odd-order hamronics, which can greatly "improve" any audio which is digitized at lower than 70kHz. Is that "good?" Is that "bad?" "

I was only responding to that direct statement, and I didn't start that discussion.

I never said "unbalanced is better." Look above to see for yourself.
Neither did I say that balanced is always better. I have heard unbalanced audiophile gear that thoroughly blew away a lesser manufacturer's balanced gear.

I have designed lots of both kinds of gear for the most varied applications, I have measured it, and I have listened to it. Ditto as a user of a lot of consumer and pro gear both.

As I said in my post, if you're on location or in a noisy environment you may need to use balanced cables no matter what. If there is electrical interference, the prudent thing to do is to use balanced cables if you can. See my previous post for an example when people can't do that.