Balanced Audio Technology Reduces Noise in Professional Systems

Have you ever been frustrated by annoying noise when connecting audio equipment? This issue becomes especially pronounced during long-distance audio signal transmission. A newly released guide delves into balanced audio technology, offering clear solutions for professionals and enthusiasts alike. This article explores the differences between balanced and unbalanced audio, their working principles, advantages, and practical applications to help achieve cleaner, clearer sound.

Balanced audio is a connection technology designed to minimize the impact of environmental noise on audio signal quality. Compared to unbalanced audio, balanced audio offers distinct advantages for long-distance transmission, as longer cables tend to introduce more noise. Balanced audio cables work best when paired with balanced equipment.

The key to recognizing a balanced cable lies in the number of contacts on the connector. Typically, three or more contacts indicate a balanced connection, while two contacts signify an unbalanced one. A balanced mono connection requires three pins (two signal wires and one ground), while a balanced stereo connection needs five pins (two signal wires per channel plus a shared ground).

Common balanced audio connectors include:

• 3-pin XLR (balanced mono)
• 4-pin XLR (balanced stereo)
• 3-pin Mini-XLR (balanced mono)
• 4-pin Mini-XLR (balanced stereo)
• 4.4mm Pentaconn (balanced stereo)
• 3.5mm balanced mono (TRS)
• 3.5mm balanced stereo (TRRRS)
• 6.35mm (1/4") balanced mono (TRS)
• 6.35mm (1/4") balanced stereo (TRRRS)

The "phone connector" is a common audio connector, most frequently seen in the 3.5mm size used for headphones. These connectors are typically described by the combination of Tip (T), Ring (R), and Sleeve (S). Thus, a two-contact phone connector is "TS," while a standard stereo headphone connector with three channels (left, right, and ground) is TRS. Since balanced stereo requires five contacts, such connectors need three rings in addition to the tip and sleeve, described as TRRRS.

Balanced cables contain two identical "leads" that transmit signals from Device A to Device B. These signals are sent with opposite polarity. Both leads inevitably pick up interference (RF, electrical noise, etc.). Because each wire collects identical interference, when the receiving device flips the polarity back, the result is a clean, low-noise input signal.

1. Step 1: The output device sends two identical signals with opposite polarity.
2. Step 2: During cable transmission, unwanted noise is introduced. Since the leads are close together, they pick up identical noise.
3. Step 3: The input device's circuit reverses the polarity of the previously inverted signal. When combined, the noise cancels out.

Balanced audio technology offers significant improvements in audio quality and transmission efficiency:

• Louder signals and greater dynamic headroom: Balanced cables are less susceptible to signal loss over long distances, allowing for louder transmission with better dynamic range. This means equipment doesn't need to be turned up as high to achieve desired volume levels while preserving the source material's dynamics.
• Elimination of harmonic distortion: Output circuits (like speaker amplifiers) may produce subtle harmonic distortion. Balanced connections can cancel these distortions, delivering clearer, more accurate audio reproduction.
• Preserved detail and transparency: Balanced audio maintains the source's detail and transparency, eliminating artifacts for more precise, realistic, high-fidelity sound.

Most consumer-grade audio equipment features only unbalanced inputs and outputs. "Prosumer" devices may mix balanced and unbalanced connections, while professional equipment typically offers balanced connections—except for guitar amplifiers, instrument cables, and speaker cables.

Combining balanced and unbalanced equipment usually results in an unbalanced connection. While unbalanced-to-unbalanced and balanced-to-balanced connections are straightforward, mixing the two can complicate matters. Consider these scenarios:

1. Unbalanced output to balanced input: If your output device has an unbalanced output (e.g., 1/4" TS jack) and you're connecting to a balanced input (e.g., 1/4" TRS jack), standard TS/TS, TRS/TRS, or TS/TRS cables will work. However, the signal remains unbalanced. Custom configurations (e.g., TS or RCA to XLR) are possible but may require specialized cables.
2. Balanced output to unbalanced input: This depends on the output circuit design. In many cases, it works, but the signal becomes unbalanced. Potential issues include unwanted distortion or, in extreme cases, damage to the output device. Always consult the manufacturer's manual for compatibility.

The term "stereo" can cause confusion when describing balanced audio cables. Balanced cables (e.g., XLR or TRS) are mono—they carry one independent audio signal with opposite polarity. For devices with balanced I/O jacks, two balanced cables are needed for stereo (e.g., "audio input left and right"). Exceptions include 1/8" or 1/4" headphone/aux jacks, which appear balanced but aren't—they're stereo connectors carrying independent left/right signals without dual leads. True balanced stereo cables essentially bundle two balanced cables in one sheath.