4 comments / Posted by Bruce Ohms

 

XLR vs 1/4-inch Cable

If you’ve been around a mixing board, recording interface, guitar amp or a PA system, you’ve probably dealt with balanced and unbalanced inputs or outputs (although you might have not noticed the differences immediately)! This article will discuss the basic differences between the two connection types and what they mean for your pro audio rig.

Common Examples of Balanced Connections

A balanced connection is a three-conductor connector, such as XLR or TRS ¼-inch cables. XLR connectors are the most common balanced audio connectors. They are identifiable by their 3-pin design, which consists of positive, negative, and ground. They are very durable, making them ideal for microphones, which endure rigorous stage use.

TRS (tip ring sleeve) connectors are less common, and upon first inspection appear to be standard ¼” plugs. However, they come equipped with an extra ring on their shaft, which is usually black. These connectors are also found in stereo headphones and other audio equipment that utilizes left and right signals.

Note: a stereo TRS can be the same cable, but the use is very different.

Balanced Connectors: Under the Hood

If you open these cables up, you’ll find three conductor components: two identical wires that are twisted together, and then combined with a third conductor, usually made of copper braid or tin foil that is the shield. The two conductors, usually pins 2 and 3, are the same signal sent out of phase of each other. When the receiving end receives these two signals it subtracts them. Thinking back to our negative number math, when you subtract a number from a negative number you are adding the two numbers. The balanced connection works the same way with them adding at the destination. This works to cancel out line noise, grounding issues, and electromagnetic interference that may arise, especially over longer cable runs. Because the two signals are out of phase and identical the noise and interference is common or in phase on both wires, so when they are subtracted at the destination the noise is reduced or canceled. Another benefit to balanced cables is that the two signals are all you need. You don’t actually need the ground to complete the signal path. This is handy with DI boxes and other product to product connections where the ground connection may be causing the noise issue. The benefits of a balanced audio system are lower noise and a cleaner signal with more headroom. As such, balanced connections are found in most pro audio applications such as microphones, mixing consoles, and power amps. In these instances, a clear, strong signal is essential!

Note: There is another connection called the ground compensated output connection where typical balanced connectors are used, but they are not truly balanced connections. The concept here is that pin 3 is a special signal ground. These connections are expecting a balanced input to receive them to work properly. The concept is similar with the cancelation of common noise, but, because the inverted signal is just a ground, the headroom is less and the cancelation is not as good. But they are still better than unbalanced connections in most cases.

Unbalanced Audio

Unbalanced connections are generally found on instruments like guitars, basses, and keyboards and consumer-grade electronics, such as home stereos, MP3 players, and even your cell phone headphone jack! The instruments use the standard ¼-inch TS (Tip Sleeve) cables and the consumer-grade products are usually the smaller stereo ⅛-inch TRS plugs. The older RCA connectors are also in this category. Inside these connectors you will usually find a single wire and a second conductor, usually made of copper braid or tin foil that is the shield. In the TRS stereo cables there is a second wire like the balanced cables, but this is so the left and right signals each have a wire. Since these unbalanced cables are usually not long cable runs, these connections work just fine for these applications.

The Verdict

You can only use the connection that your gear has, but using the right cable and connectors is important. If your connection is unbalanced keep the cable runs shorter. Guitar cables over 20 feet can really turn into an issue depending on the interference at your particular location. If you have to go longer, use a buffer pedal to go from your pedal board to your amp. Click here to read our article on buffered vs. true bypass pedals. 

When it comes to pro audio, balanced connections win hands down. Fortunately, most professional equipment is equipped with balanced inputs and outputs, and the only thing you need to do is make sure you’re buying the right cable. Remember the DI box is used to convert an unbalanced connection to a balanced connection when you need it. Carvin Audio offers a full line of quality balanced XLR, unbalanced ¼-inch cables and a DI box.

Comments

  • Posted On July 14, 2016 by Dick

    Keep up this type of stuff. Most musicians and production people need to know and understand these things. I have been doing this for many years and I still find it amazing how few “pro’s” and “semi-pro’s” even have a clue about so many simple technical things.

    One trick that needs to be addressed is mixing stereo-mono compatible audio. The mix minus how and why. Some current big names have forgotten or never learned this one. Listen to some early Motown stereo stuff in mono and you will hear what I am talking about.

    Thank you and keep up the good tips.

  • Posted On July 13, 2016 by Michael A. Hicks, MBA

    I shared the link for this with my subordinates and co-workers. Very well written, brief, and informative. Thanks!

    Michael A. Hicks, MBA
    AV Setup Specialist VII
    (“BoilerCast” Operator)
    IT Customer Relations
    Purdue University
    West Lafayette, IN 47907
    mahicks@purdue.edu
    purdue.edu/boilercast

  • Posted On July 12, 2016 by Bruce Hobright

    My son has a cr in v3 100 watt tube amp and carvin 4×12 bottom. if we run a 1/4 to1/4 unbalanced cable to an unbalanced or balanced input we have to crank the output on the line out and barely get any sound through the pa. would a di box and XLR cable take care of this problem or does the amp need serviced?

  • Posted On July 12, 2016 by William McKenzie

    Very nice info. Keep it coming !!!

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