Balanced vs Unbalanced Lines - What’s the Difference?
A balanced line using TRS connectors, used between a mixer or preamp and an audio interface or to an FRFR speaker
If you are a guitar or bass player whose whole time playing has involved connecting your instrument to an amplifier, you have been using what is called an unbalanced line, and very likely have neither noticed nor cared. That’s the way that things have worked since pickups and amplification showed up and continue to work today. That’s not likely to change anytime soon, so need for concern.
Yet when you start to look at recording interfaces and PA systems and preamps and FRFR speakers, you have or will hear that they used balanced outputs or balanced lines. Since a distinction is clearly being made, it would not hurt to understand the difference and why balanced lines are preferable to unbalanced lines in some scenarios.
Let’s Start with Unbalanced
If you’ve ever unscrewed the connector cover (if you can at all) on your guitar cable, you will see that there are two connection points inside the standard 1/4” connector. There is a wire, wrapped in a cover of some sort (the insulator) that is connected, most commonly via a solder joint to a central connection, and a second connection, soldered to the edge of the connector. Most often this second connection is a wound wire set, but in cheap cables it might be a piece of foil.
Your guitar or bass signal travels from the pickup on that centre core wire and the point in the connector to which it is soldered is called the Tip. When you look at a 1/4” plug you see that the tip is separated from the rest of the connector by some kind of insulating ring, often simple plastic. The second connection to the connector is called the Shield and so we call this type of common 1/4” connector a Tip Shield or TS connection. The signal runs down a single conductor and the cable contains a second set of wire usually wrapped around the insulator protecting the centre conductor. In cheap cables, this will be foil not wire. This second conductor serves also as the ground of the circuit. The ground or shield serves to help reduce noise during transmission, although the effectiveness of this is dependent on the quality of the cable. A stranded centre conductor and a stranded shield provide the best options. Foil shields tend to be noisy and crackle when the cable is moved, and solid centre conductors are less conducive to bending and will tend to break rendering the cable ready for the trash. You actually do get what you pay for when it comes to instrument cables, you just won’t be able to see what you are getting unless you open the connectors.
Balanced Lines
In a balanced line, the signal runs down two conductors instead of one. Each conductor is independent and there is still the shield. The same guidelines about stranded cables over solid and foil apply. Contrary to some misunderstandings, the conductors are in phase with each other, meaning that the peaks and troughs of the sine wave of transmission are in the same place at the same time. A balanced cable never introduces phase cancellation. Inside the cable these two conductors are often twisted together to increase their noise and interference reduction benefits. The conductors are soldered to a different kind of connector. On the outside it is still a 1/4” connector but instead of one insulation ring there are two. They correspond to connections inside the connector. The first is just like the unbalanced connector and goes to the tip. The second conductor goes to a different connection that is unique to this connection called the ring which is the area of the external connector right after the tip. The shield goes to the frame of the connector as in the unbalanced connection. From a wiring perspective, it goes tip to tip, ring to ring and shield to shield. This balanced plug is called a Tip Ring Shield connector or TRS connector.
The Jack
When we plug a cable into a jack, the jack has to match up to the connector being used, so a TS cable needs a TS jack and a TRS cable needs a TRS jack. The internal parts of the jack will be in different places depending on whether the jack is TS or TRS and this is why using a TRS cable into TS jacks will often not work. Your instrument has a TS jack. So does your amplifier or your pedals, unless they are designed up front for TRS. This is most often done if the instrument or pedal is configured for stereo on a single plug. Much more common is an instrument with two output jacks. If two separate cables are used each runs from a single pickup to its own amplifier. This is found on Gibson’s ES models with the S designation or on Rickenbackers with Rick O Sound connections. One of the jacks is designed to shunt the ring to the tip so signals from both pickups are on the same conductor if the stereo option is not used at the instrument.
When we find a TRS jack on a pedal, that is not used for an Expression pedal or multi footswitch, it means that it can accept a stereo in. In most cases this means you need to add a stereo adapter Y cable that will put one side on the ring and the other side on the tip from two separate unbalanced cables. The Strymon Iridium input is like this. It’s annoying and only ever done for space considerations because it means an extra cable is required for full use.
Why Balanced?
Balanced circuits require not only the cable to be balanced but the outputs and inputs as well. You can use a device called a Balun to convert but that is more common in telephony and video. A balanced circuit has equal impedances on both lines. This is very useful in reducing noise and interference picked up over the length of the cable. Consider that an antenna is really just a wire. The lower the overall impedance of the circuit, the greater the probability that the circuit will be balanced. On a common PA or mixer you will find unbalanced and balanced inputs. Most folks recognize the XLR connector used for microphones and this is a balanced circuit. It was originally built this way to support external transformers for microphones and is still used today because it is reliable and it works. The great Les Paul had his signature guitars built with low impedance pickups and XLR outputs. The mixer or PA may also have 1/4” balanced and unbalanced inputs. Some distinguish the inputs while others will flip a balanced input to unbalanced if a TS plug is inserted.
Outputs on mixers and inputs on interfaces will often use a combination connector that can leverage either TRS cables or XLR cables. Sometimes you have TRS on one end and need XLR on the other. This is common with some pedals that offer a proper line out, such as the aforementioned Strymon Iridium. Some pure preamp pedals also offer an XLR out directly. Check your devices to order the proper cable.
I’m not going to get into the math of how balanced impedances work. If you want to know more, there are many deep articles on this available as well as ones that explain the XLR model in greater detail.
Should I Convert My Instrument?
In a word, no. All the devices that you will typically connect your instrument to are seeing an unbalanced line. If your guitar output is changed to be balanced, you will need to have custom cables made or use a Balun at the effect or amplifier end. Instead of doing that, buy a better cable. You are looking for a cable with a flexible and thicker outer cover, that has a braided shield and that uses braided conductors that are twisted together inside the cable itself. There a myriad cables in the marketplace and it is near impossible to determine the cable quality by simply looking at them. A better cable will cost more, and in the long term will be worth it, but there is no need to spend $70 on an unbalanced 10 foot guitar cable, that’s just paying for nothing. I have found success with the Ernie Ball branded guitar cables and am now buying the Pig Hog brand because they use a heavier outer cover and are less prone to tying themselves into knots.
I hope that you found this article useful. If you have questions, post them via this link. Until next time, peace.
