Balanced vs. Unbalanced Cables: What Gigging Musicians Need to Know
Introduction (main difference)
Musicians mostly use two different types of cables: Instrument cables for guitar or bass and microphone cables for microphones.
Let’s go to the next step.
Instrument cables are unbalanced. Microphone cables are balanced.
For now, let’s say that the main difference is that an unbalanced cable has one signal (conductor) wire and a balanced cable has two signal wires. The additional signal wire in a balanced wire is used to eliminate noise. Both cable types also have a ground wire which is all those tiny wires that surround the main signal wire(s).
Unbalanced cables have 2 wires: 1 signal + ground
Balanced cables have 3 wires: 2 signal + ground
Unbalanced cables
Unbalanced cables typically have ¼ inch TS (Tip, Sleeve) jacks. An RCA cable is also unbalanced. Instrument unbalanced cables are cheaper than balanced and do a good job of sending guitar signals to an amp.
The signal cable picks up various noises which become noticeable in cables longer than 5 or 6m. As long as we use 3-6m cables to connect our guitar to an amp we are good.
Balanced cables
What are balanced cables?
Balanced cables are designed to eliminate noise, which ultimately makes it possible to use very long cables: up to 100m. The second signal wire eliminates noise.
Let’s explain this. Microphones produce a very low signal compared to guitars. Unbalanced cables are not suited for use with microphones because noise is too loud compared to the weak microphone signal. Instrument signals are much stronger than mic signals so noise is less of an issue with unbalanced cables.
When to use balanced cables?
- When you are using weak audio signals such as microphones
- When you need to send audio signals to devices that are farther than 6-8m from you
How does a balanced cable eliminate noise?
We mentioned that the added second signal wire is used to eliminate noise. How does that work? By flipping the polarity of the signal. Imagine the flipped signal as a mirror image of the original signal.
Every balanced OUTPUT is designed like this:
- There are three (3) male pins
- The audio signal is split into two identical signals
- The first is normal (HOT) and is left as is
- The second signal’s polarity is flipped (COLD)
- The third pin is GROUND
Every balanced INPUT is designed the same way. It once again flips the polarity of the second signal bringing it back to exactly the way it was before. Two flips are the same as no flip. The receiving device now adds these two identical signals which combined are stronger than before.
The microphone signal is flipped BEFORE entering the balanced cable. Noise on the other hand enters the cable AFTER the first flip. In other words, the microphone signal enters the cable at the XLR jack while noise enters the cable through the signal wires throughout the whole length. Both signal wires (hot and cold) receive identical noise (same polarity) so when the cold wire gets flipped at the receiving end the noise in it becomes negative in polarity compared to the noise in the hot wire.
When the receiving device combines the noise from the two wires it gets canceled. This is called common-mode rejection.
The catch is in the fact that the microphone signal flips twice but the noise flips only once. This is why the flipping of polarity cancels only noise, not the main signal.
Types of balanced cables
We have already mentioned the XLR cable which is used for microphones and mixers. Some audio devices use ¼ “ TRS (Tip – Ring – Sleeve) jacks for connections instead. The principle is the same as that for XLR connections. There is an added RING which allows the same three signals to be sent and received.
Unbalanced cables can also be used with TRS inputs as long as you are not using them for balanced signals.
Frequently asked questions
Where does polarity flip occur?
The actual polarity flippings occur in the sending and receiving devices. There are no polarity flips being made in balanced cables. They are merely responsible for sending whatever signal they receive.
Why don’t we use balanced cables for all signals?
Because it is a more expensive method than when using unbalanced cables. First, a balanced cable has an additional cable, and second, every instrument would have to have a balanced output which is unnecessary. As we said before, instrument signals are much stronger than microphone signals so noise is not a major issue when using shorter cables.
Sending unbalanced signals through longer cables
When we need to send an unbalanced instrument signal to a distant location we use a DI box to convert the signal into a balanced signal. This is done to eliminate noise that is significant in longer cable runs.
Where does noise come from?
Noise can be caused by:
- Power cables: Do not run them parallel to audio cables. They can touch each other, but best if at a 90-degree angle.
- Long cables: Not an issue for balanced cables but for unbalanced cables avoid using cables longer than 6m
- Grounding…
Conclusion
Now we have a better idea of when to use what type of cable. Balanced cables are needed when using low-signal output devices such as microphones and when we need to send signals for longer distances. Unbalanced cables are perfect for instruments with a higher output signal for distances less than 5-6m. The guitar is a perfect example.
The main factor to consider is the potential noise volume compared to an audio signal that is being sent. If the noise is tolerable, use unbalanced cables. When noise is substantial compared to a signal, use balanced cables to cancel noise.
Every musician should be familiar with the differences between unbalanced and balanced cables. Without going into electronic details knowing these simple yet effective principles will help you with future audio applications. When to use which cable or when to use a DI box are the most common dilemmas for musicians.
Having different types of cables for every possible scenario is essential for frequent gigging. What else do musicians need in their accessories case?
