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mghia Veteran user Kymystical 387 Posts |
When looking at mic. and audio inputs, can someone explain the pros and cons of Balanced vs. Unbalanced connections and how important they may be to the over all sound quality of a system?
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silverking Inner circle 4574 Posts |
As a rule use balanced inputs whenever possible and you'll have less problems with spurious noise.
There are no cons to using balanced inputs, the deciding factor is always whether your equipment offers you the option of using balanced inputs in the first place. Balanced inputs have been considered the domain of the "pro" and unbalanced inputs the domain of the "semi-pro" because of the difference in input sensitivity. In the end though, most professional audio types will use balanced inputs and outputs (unless they're plugging their iPods into the mixing console!) |
Dan McLean Jr aka, Magic Roadie Special user Toronto, Canada 804 Posts |
What you're calling a "balanced" mic (one having an XLR connector) has two very real pro's.
- The mic cable can be, for all intents & purposes, on infinite length. There are - Generally speaking, it will be of better quality than a mic with a 1/4" connector.
Dan McLean Jr
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James Adamson Special user Deatsville - Holtville - Slapout, AL 945 Posts |
Unbalanced inputs and outputs are found more on the cheaper systems. You can use it as a gauge for the quality of equipment.
This does not mean that only cheaper systems have them as some Pro audio equipment will have both.
Be remembered for performing what looks like MAGIC, not skill.
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Chris Oberle Elite user California 444 Posts |
Very True James, very Very True.
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mghia Veteran user Kymystical 387 Posts |
Quote:
On 2006-12-10 08:40, Dan McLean Jr aka, Magic Roadie wrote: Can you explain WHY you can go an infinite length with XLR and not have a signal loss? That is, what does standard audio cable do different that makes it weaker? |
Dan McLean Jr aka, Magic Roadie Special user Toronto, Canada 804 Posts |
Quote:
On 2007-01-03 00:42, mghia wrote: That's a very good question, and one that requires us to divide the answer. "Balanced" & "low-impedance" are actually two different concepts. The difference is in the equipment that the cable plugs into. If both the mic & the pre-amp (usually a mixer) are low impedance, then a proper cable between them can go over 1000' with no signal loss ("infinite" was an exaggeration). If both the mic & the pre-amp (usually a mixer) are balanced, then a proper cable between them will help to avoid the introduction of noise from nearby dimmers, flourescnet lights, etc. Typically, a cable that is suitable to connect two balanced & low-impedance devices has XLR connectors on both ends, but other connectors can be, and sometimes are, used. The cable itself is also constructed to facilitate this type of signal. Hence, a balanced & low-impecance mic plugged into a balanced & low-impedance pre-amp with an appropriate cable can run a very long distance with minimal risk of added noise. Typically, this is called a "mic cable". Certain UNbalanced & HIGH-impedance devices (some musical instruments, DVD players, etc) can be converted to balanced & low-impedance with the use of a DI box. DI means "direct input" or "direct injection". With these, you use a short cable bteween the input device and the DI, and a mic cable between the DI and the pre-amp. Although I've tried to keep this as simple as possible, please feel free to ask questions, and I'll do my level best to answer them. Cheers from Toronto!
Dan McLean Jr
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mghia Veteran user Kymystical 387 Posts |
The follow up is then to ask WHY low impedacne can go further without noise/signal loss since it is still just copper wires in the cable. What is different about a XLR system?
What does BALANCED really mean? (Electronic definition wise)? What is going on that makes it work "better" and how much does that wire config aid this? What do each of those 3 wires carry on it? I am not looking for an overly technical answer. Just enough to get the basic concept. |
Dan McLean Jr aka, Magic Roadie Special user Toronto, Canada 804 Posts |
Quote:
On 2007-01-05 09:13, mghia wrote: I fear there are ONLY very technical answers that will answer your questions! Too technical for this forum. Just search the Web and you'll find tons of geeky answers. There are many possible scenarios for connecting two devices (too many to list here), and each has a "better" way of connecting them. That being said, if the output device (in the case of this thread, a wired or wireless mic) and the input device (in the case of this thread, a mixer) have XLR connectors, then the rule of thumb is to use a mic cable to connect them.
Dan McLean Jr
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C. Loubard Special user 615 Posts |
Mghia,
Magic Roadie is spot on. Without getting to technical, I will try to explain balanced versus unbalanced Balanced has three wires; a hot lead, cold lead, and a ground. the hot and cold leads are out of phase to each other-- they cancel each other out. If you ever reverse the polarity on one speaker and leave the other correct, you will hear what out of phase is. This flip in polarity is used to eliminate unwanted noise introduced through ground, which is the third wire in our balanced wire. in a sense you could say our hot and cold are floating while the ground is connected to the chassis of the electronic components, however, at different impedances. This already sounds technical... sorry! when we say low impedance, it means low resistance in relation to an electric current. The best I can describe is, if you have low impedance, you will be able to travel farther easier before you tire out. unbalanced has the drawback of higher impedance, while one of the leads is connected to chassis ground. the difference in electronics between components is going to give you an unbalanced signal and more resistance-- more voltage drop over longer runs. it should also be noted, long stinger (extension cord) runs will produce voltage drop as well. Good god, this really isn't easy to explain... Perhaps, it would be wiser to follow Magic Roadies suggestion and google it. sorry if I was unclear |
mghia Veteran user Kymystical 387 Posts |
It is ok to be geeky here. I was just trying to let you know I was not trying to be a PHD on the subject, just get the basics. It is enough to go on. Good job. However, with unbalanced, is that not why they use SHEILDED wire? Or something like Mega brand wire that the one wire is twisted to help block noise since it is not running in parallel with the other? I understand that there will still be drop off but it seems to be less due to the wire or wire size but the lower resistance of the designed system.
Is it that much more expensive to make low impedance or is there other reasons many choose to use unbalanced? And while I am on the question train, what is the Hi to Lo adapter doing that I have. (1/4” female to XLR male) |
Dan McLean Jr aka, Magic Roadie Special user Toronto, Canada 804 Posts |
Quote:
On 2007-01-05 23:58, mghia wrote: It sounds like this probably contains a transformer that converts a balanced, low-impedance, mic-level, XLR signal to an unbalanced, high-impedance, line-level, 1/4" signal. In other words, it lets you plug a standard XLR mic into a "non pro audio" pre-amp, like a DJ mixer or an inexpensive PA mixer or a guitar amp. Essentially, this is an inexpensive, backwards DI. With the requisite gender-reversing adapters, this could actually be used as a DI to plug, for example, a guitar or a keyboard into an XLR input on a mixer.
Dan McLean Jr
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silverking Inner circle 4574 Posts |
Just to put in another comment in addition to Dan and C.Loubard's excellent remarks above.
I use the following basic explanation when speaking to technical theatre students in university. They often stare back at me like I'm speaking in tounge, but in any given class, most wind up basically understanding a balanced circuit. Please be aware that I am GREATLY simplifying the concepts in order to make them understandable and easy to access. I also use "music signal" to describe the actual sound we WANT to hear come out the other end of any given (balanced) signal cable. First, the construction of the cable: The shield helps to prevent extranious RFI and other noise from getting picked up by the cable. The "in phase" music signal is on one lead. The "out of phase" music signal is on the other lead. (both in and out of phase signals are identical, just out of phase with each other). The only thing common to both wires at the start of the cable is the music. They two signals ARE out of phase from each other, but they ARE ALSO common to each other (that is to say the same thing, just out of phase). Any noise picked up on the longer run of a balanced XLR cable will be picked up unevenly between the "in phase" and "out of phase" lead (both of which carry our music signal). Any noise that starts to get picked up by the cable IS uneven across the two music signal leads, when the noise component of the signal are combined they will cancel out (this is the noise that's canceling)......the music is identical on both leads so when each channel is brought back into phase the music is perfect and all the noise has been cancelled out (because it was not identical across both leads). The principal is simply that noise cannot be evenly picked up on the music signal cables two leads which are out of phase with each other, and anything that isn't identical (only the picked up noise) is gone when it's combined at the other end. You may also hear about "actively balanced", "electronically balanced", and "transformer balanced"......all of which accomplish the same basic thing, but in a different way. In general, balancing a system with transformers is considered to be the best method. Balanced systems also have MANY other things going for them that require much deeper understandings of the complete system under discussion, but the above is the basic reason a balanced system or circuit is considered more noise resistant and capable of moving a signal for a greater distance than an unbalanced circuit. |
mghia Veteran user Kymystical 387 Posts |
The use you described is backwards. It is used to go from 1/4" unbalanced mono do you can plug into an XLR system. I bought it and have used it when I was working old schools who only had an XLR input in front of the stage. So I guess I am now asking if from that point on, if the system is balanced?
I am not sure if it works both directions. It is a male XLR output. Quote:
On 2007-01-06 07:44, Dan McLean Jr aka, Magic Roadie wrote: |
Dan McLean Jr aka, Magic Roadie Special user Toronto, Canada 804 Posts |
Quote:
On 2007-01-08 00:36, mghia wrote: I had it backwards, mghia (if that is your name), because I mis-read your previous post. Still, a DI can work in both directions. At least a passive DI can, and I assume an active DI can as well, but I'm not certain. Quote:
So I guess I am now asking if from that point on, if the system is balanced? Not necessarily. The status of each part of the system is dependant upon the component parts. For example, your mic-to-mixer path may be unbalanced, but your mixer-to-amp path may be balanced. Each link is independent.
Dan McLean Jr
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silverking Inner circle 4574 Posts |
Dan has highlighted the most misunderstood part of the "balanced" and "unbalanced" disccussion.
That is the understanding that there's a huge difference between a "balanced system" and a single piece of balanced equipment. In professional audio, we usually try to create a completely balanced audio system, and in order to do so we have to specify and purchase balanced equipment from stem to stern. We then have to ensure that all cabling remains effectively balanced and that all sheilds are properly terminated inside the connectors to minimize noise. One piece of balanced equipment doesn't mean very much without looking at what it's plugged into, and where it's going. Fully balanced systems are quite rare outside of professional audio applications. Even running your mixer to an unbalanced piece of effects equipment (then back into to your mixing console) or using an unbalanced playback device (an iPod isn't balanced for example) can introduce problems that balanced equipment is designed to remove. The most effective method for the users of this forum to enjoy the quiet and dependability of a balanced system would be to employ an "all in 1" balanced mixer/amp and either a XLR microphone like a Shure SM58, or a wireless microphone with a balanced output on the reciever. Add to that a balanced output on your playback device, and you have a balanced system. It's worth noting that most inexpensive wireless microphones do NOT have a balanced output on them, and therefore your problems begin far earlier in your system than they otherwise would have. All of the above shouldn't be taken to indicate that a high quality unbalanced system can't be designed.....it can. The issues with unbalanced equipment usually relate to overall quality and maintence of things like cables and connectors (and the previously mentioned need to keep cable runs as short as possible). Another example, the RCA output connector (or 1/8" to RCA break-out cable common on iPods and such) is notoriously undependable, and prone to all sorts of issues from minor corrosion to bending of the pin or tangs. It's not that RCA's can't be used, it's that most folks use them well after they should be thrown into the garbage. Unbalanced cables are often made of the cheapest possible cable stock. This creates noise and dependability problems........and on and on it goes! Maintain ALL your cables, replace them if they get "squished", take care of your connectors by spraying them with a high quality cleaning spray, and keep your cable runs as short as you can (and use a wireless mic with a balanced output on the receiver into a balanced input on your mixing board) ........ if taken care of, you shouldn't notice any difference in a typical magic PA set up whether it's balanced or unbalanced. |
ScottRSullivan Special user 874 Posts |
Dan, excellent information! You really help explain the technical for everyone. Thank you.
I might add to your last statement about only parts of a system being balanced/unbalanced. Once one section goes unbalanced, the who thing is unbalanced, from what I remember. Also, from what I remember, you can't always assume XLR = balanced. Balanced wiring has nothing to do with the connector. In fact, isn't it possible to have balanced TSR and also possible to have unbalanced XLR. Though most XLR is balanced, you can't tell, just from the connector. But it WILL state it on the cable itself. Of course, this could all be memories from eating pizza before going to bed last night at 4 am! Scott |
C. Loubard Special user 615 Posts |
Scott,
You are correct. with stereo tsr you can make balanced audio cables. In fact, pro boards are 1/4" outs, with exceptions of course. Any audio gear for film work will feature XLR I/O (in and out), with the whole system being balanced. Of course we are assuming we are working with professional level components... not prosumer. I've had to make many a cables to connect between XLR and TSR equipment |
Michael Taggert Special user Fredericksburg Virginia 656 Posts |
One note here was the question about shielding. a shielded cable has a prtective wrap that is not part of the ciruit that effective reduces the interference from such things as lighting cables and dmx control cables.(that strange buzz you get when the lights go up and down. sound cables and amplifiers will pick up these signals and amplify them to an audible level so the sound cables are shielded to try and thwart this. sometimes it works.
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Dan McLean Jr aka, Magic Roadie Special user Toronto, Canada 804 Posts |
Just to clarify ...
Quote: Yeah, both balanced pre-amplifier cables and unbalanced pre-amplifier cables are "shielded".
On 2007-01-14 16:31, Michael Taggert wrote: Quote:
a shielded cable has a prtective wrap that is not part of the ciruit The "shield" is (almost always) connected to both connectors (in rare occassions, on just one end), and therefore to ground in the connected devices. To over-simplify, when the shield captures the interference to which you referred, it drains that interference to ground, via one of the connected devices.
Dan McLean Jr
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