Last time we looked at probably the most common jack you’ll encounter, the 1/4″ mono jack, this time, we’ll meet its close relative, the 1/4″ stereo jack, AKA the balanced 1/4″ jack or the 1/4″ TRS jack
Looking at the picture above, its pretty east to confuse with the 1/4″ mono jack, let’s look at them side by side
Notice that the Stereo 1/4″ jack adds a ring between the tip and the sleeve. These cables are almost always used for carrying balanced, line level signals.
Where the mono 1/4″ jack is meant to carry a signal wire and a ground wire, or the positive and negative wires of a speaker cable, the stereo 1/4″ jack carries TWO signal wires and a ground wire.
When used as a jack for stereo gear, the tip will go to one side of the stereo spectrum and the ring will go to the other. There is no published standard that I am aware of, but for instance, most Sennheiser headphones I’m aware of have the tip go to the left headphone and the ring to the right headphone. Always test to be sure.
When used as a jack for balanced gear, the tip will normally go to the positive wire for the gear in question and the ring will go to the negative side of the gear, with the sleeve wire carrying the ground. Again, double check to be sure, manufacturers will always try and throw you for a loop.
One place you will sometimes find these jacks in use are as insert cables on certain gear, like cheaper mixing consoles. In this case, the tip will go to the send or the return and the ring will go to the opposite end, while the ground is shared by both. In the nearly ubiquitous Mackie brand mixers, the tip in every case I’m aware of goes to the send and the ring is the return. Both the send and return will be unbalanced, and share the same ground. Again, doublecheck to be sure, because many companies will use the opposite configuration.
Shown here is a female TRS jack. Use your continuity checker to figure out which terminal goes to the tip, which goes to the ring and which terminal goes to the ground