Pro-Audio devices sometimes call for TRS cables. What are these, and why do they frequently cause confusion? Let’s find out.
The letters TRS stand for Tip, Ring, and Sleeve, and refer to the parts of the jack plug that the different conductors are connected to. A TRS cable has three conductors vs the two on a standard guitar cable. A guitar cable is a TS, or Tip Sleeve cable.
The jack plug at the top is a TS jack. The pointed metal bit at the end, is the tip, and the long metal shaft is the sleeve. The black band between them is an insulator preventing the two parts of the jack from shorting together. Notice we said ‘band’ and not ‘ring’. It’s easy to look at a TS jack and assume the black insulation ring is the ‘R’ in TRS but it’s not. The TRS jack is at the bottom. It has a metal ring in the middle which is the third conductor. The three conductors are separated by two black insulation bands.
There are other types, most commonly a TRRS which has two rings, and four conductors in total. TRRS jacks are often used for stereo headsets with microphones where four conductors are needed for ground, left channel, right channel, and mic.
A TS cable is fine for carrying a mono instrument signal such as from a guitar pickup to amp. The tip carries the signal and the sleeve is the return path and also usually the ground. Sometimes an additional conductor is needed such as for carrying a stereo signal, a balanced signal, or when connecting a voltage divider such as in an expression pedal. When a device requires a TRS cable, it’s because the application needs a third wire, and it will normally not work correctly if you try to use a TS cable in it’s place.
When we refer to a TRS cable, it normally means that there is a TRS jack at both ends. However, there is also another variant called a TRS Insert cable or TRS Y cable.
The insert cable has a TRS jack plug on one end and two TS jack plugs on the other. They are called insert cables because they are often used in recording studios to connect outboard equipment to insert points on a mixer. They can also be used to connect stereo signals between equipment where device A uses separate jacks for left and right channels, and device B uses a combined TRS jack.
Like regular TS cables, TRS cables come with different jack plug sizes. The most common in pro-audio is the 1/4″ jack. The outside diameter at the sleeve is 1/4″. These are sometimes also called phone jacks, since they originated in the 19th Century for use in the first manual telephone switchboards. Wikipedia suggests that the 1/4″ jack may well be the oldest type of electrical connector still in widespread use having begun its life in 1878.
The smaller jacks commonly used are 3.5mm for computers and 2.5mm for handheld devices. Since much of the world had switched to the metric system by the time these smaller jacks were created, we now have to deal with the mixed units of measurement of the 1/4″ phone jack from the 1800’s and the modern metric computer audio plug.
A 1/4″ jack is 6.35mm
A 3.5mm jack is approx 1/8″
A 2.5mm jack is approx 3/32″
So, what about balanced cables, are TRS cables balanced or not? In short, no, the cables themselves are not balanced, they are simply cables with three conductors, it’s the interfaces that determine if a connection is balanced or unbalanced (single-ended). However, a TRS cable may be required to use a balanced connection. A balanced interface normally has three wires:
1. Reference (usually ground)
2. Signal (hot)
3. Inverse (cold)
A balanced connection can help reduce noise from electromagnetic interference by using a technique that sends two copies of a signal 180 degrees out of phase with each other. There’s a more complete explanation of how balanced interfaces work here
For a balancing to work, the equipment you are connecting, must have a balanced interface. If it does, then you’ll need to use a three-wire cable. Often balanced connections use an XLR cable but sometimes, 1/4″ TRS cables are used instead. We may see TRS cables referred to as balanced cables for this reason, but it’s a bit misleading because it’s not the cables that are balanced. Sure, you may need TRS cables to connect two balanced devices together, but just using a TRS cable to connect two single ended devices together will NOT turn it into a balanced connection.
In conclusion, a TRS cable is a cable with round phone type connectors and three conductors called tip, ring and sleeve. The jack plugs maybe different sizes, so check you have the correct size for your gear. The cables can be used for different applications such as a stereo connection (right/left/ground), a balanced connection (hot/cold/ground), or a voltage divider connection (input/output/ground). However, the cable itself is the same.
If you need a TRS cable for your rig, check out Mission cables here.