The Difference Between Mono and Stereo Cables

The Difference Between Mono and Stereo Cables
Most standard 1/4" cables (guitar cables) have two conductors, like the one at the bottom of the photo to the right. They carry monophonic (single-channel) signals, such as a single pickup on a musical instrument.

A TRS -- aka "Stereo" -- cable adds an extra connection, which allows the single cable to carry TWO channels of audio. Here's how!

The cable at the bottom of the graphic is a "standard" 1/4" instrument cable. It has two conductors (1 and 2), separated by an isolating ring (i) so that they don't contact each other. The TIP (1) carries the "hot" or positive audio signal; the SLEEVE (2) is the ground or negative audio signal. Simple, effective, and readily available, as they have been used on a kajillion guitars, basses, and other musical instruments around the world for decades.

The stereo cable builds upon this design. It adds a RING (3) to the TIP (1) and SLEEVE (2). This, again separated by the isolating rings (i), allows a second channel to be carried by the same cable.

The TIP carries hot channel 1, the RING carries hot channel 2, and the SLEEVE gets the ground signal from both channels (combining their grounds still keeps the two channels separate.)

And now you can probably figure out where the "TRS" name comes from (Tip/Ring/Sleeve).

How It Works for Us
With bass pickup sets and certain preamps, we use this "stereo" capability to our advantage. You may have recognized that the design of the TRS plug is the same as the one on your stereo headphones for your iPod, smartphone, or other personal listening device - the stereo headphone jack works exactly the same way (although usually on a smaller, 1/8" or 3mm jack/plug). While mostly we think of stereo as an paired version of the same signal (Left and Right "versions" of a music recording), in reality they are two distinct signals that happen to form a stereo image. But the two signals can be much more different - two different pickups, a pickup and a microphone, etc. So "Channel 1" and "Channel 2" are really just a similar concept to "Left" and "Right."

The K&K Sound special pickup sets, like the Bass Master Pro, Bass Master Rockabilly, Golden Trinity Mic Combos, etc., all use the two channel capability of this design to minimize the number of wires you need to get everything set up.

So Which One Can/Should You Use?
  • If you have two different pickups and you want to blend them together with a preamp, a "dual mono" input preamp is the simplest way to do it. A separate mono cable from each pickup goes to each separate input - easy-peasy.
  • If you have a system like the Bass Master Pro, which wires both pickups to separate contacts on a single jack, then you want to use a TRS/stereo cable to connect them to a preamp with a TRS input - like the Dual Channel Pro ST or the LR Baggs MixPro. The Radial PZ-Pre, Headway EDB-2 and the Grace Design FELiX can also accept two inputs using a single TRS Cable.
  • If you already HAVE products that are mismatched (a TRS pickup output and a dual-mono preamp, or two separate pickups and a preamp with a TRS input) there are adapting cables. Often called "insert" or "splitter" cables, they have a TRS plug on one end, which then splits out to two separate mono cables. So you could use a cable like that to adapt between the pickups and preamp.

Hopefully this is easy for you to follow; if you have any questions about your specific gear, drop us a line and let us know what you've got, we'll help you get it all connected!