In one of my guides I mentioned balanced and unbalanced cables but didn't mentioned what they are, that was done on purpose because there is a whole section of things I could talk about between balanced and unbalanced cables. The reason this post is an info post not a guide is that for the most part Justin.tv and Twitch.tv broadcasters will not need to deal with how to balance a cable as most of their cables are already unbalanced and do not have a reason to balance that signal.
Long Story, Short
In the very basic terms Balanced cables are better to use in audio cable runs because they can be sent for 100's of feet (the longest I have personally done is 300 ft). However they require more requirements get a cable and signal to be balanced and are usually more expensive then unbalanced cables. While unbalance cables are better to use for short runs (less then 10 ft), they are definitely cheaper then most balanced cables, but they can introduce hum into the mix if wired or run incorrectly.
Why Balance a Cable?
Why? Because you don't want to hear hum in the mix. Audio hum occurs when the signal gets too weak for the mixer to hear so the mixer (both the mixer it self and the person operating the mixer) will attempt to gain up or level up the signal. The other way is inproper runs of cables IE when a audio cable runs along a power line. Also you can send a balanced cable potentially 100's of feet (while I have personally done a run of 300 ft I know there are people who regularly run audio cables the length of a football field)
What Makes a Signal Balanced or Unbalanced?
In a balanced signal you need three signals a positive a negative and a ground. What happens is if the requirements are met for a balanced signal, the signal is get sent in two ways the normal signal (+) and inverted signal (-). Then the receiving device does some quick calculations to the signal, if there are the same noise in both signals that gets canceled out, if there is noise in only one signal then that gets canceled out too. After all that only the signal sent by the original device is received the the receiving device.
On the other hand unbalanced cables only need two pins or signals, one is a positive and the other is the negative and ground.
What Makes a Cable Balanced?
As I said earlier balanced cables have more requirements to make a signal balanced, if any one of the requirement fails to be met the cable gets turned into a unbalanced cable and the signal automatically goes unbalanced.
- The sending device is a balanced output
- The cable is correctly balanced and properly terminated
- The receiving device is a balanced input
IE
[balanced output]
|
|
v
{balanced cable}
|
|
v
[balanced input]
==========
A balanced signal
The signal doesn't get balanced if any of these requirement are met
- The the cable doesn't have three pins or three signal
- The signal is converted from a different signal to another* ie a RCA to 1/4in converter
- The signal is a digital signal
*There are converters that do keep the balanced signals but they are only for specific types of cables
IE
[rca to 1/4 in adapter]
|
|
v
{balanced cable}
|
|
v
[balanced input]
========
Not a balanced signal
| [balanced output]
|
|
v
{1/4 TS cable}
|
|
v
[balanced input]
========
Not a balanced signal
| Digital doesn't apply here
as the signal is all there or it
isn't, there is not a in-between
like analog cables and signal
|
What Cables are Balanced and Unbalanced?
Unbalanced cables are the TS (Tip Sleeve) and RCA cables
Balanced cables are only TRS (Tip Ring Sleeve) Cable and XLR
Note: That all balanced cables can be unbalanced but unbalance cables can never be balanced.
Any questions comments can be posted into this thread or you can PM me.
