PA Speaker Cable Guide 2026: Gauge, Materials & Loss

2. Speaker Cable Construction: What's Inside a Good Cable

Many people perceive "loudspeaker cable" as a standardized product, but its internal construction determines whether it will provide years of reliable service or become a source of intermittent failure.

Four key elements of loudspeaker cable that are important when installing PA systems:

• Conductor: Copper/OFC/OCC/Tinned Copper/CCA (determines resistance and stability)

• Termination: Affects flexibility, ease of installation, and long-term reliability

• Insulation: Electrical safety and heat resistance

• Outer jacket: Protection from external influences (UV radiation, moisture, abrasion)

It should be emphasized that in real-world projects, the most common point of failure is not the cable itself, but the way it is terminated. A high-quality cable with a poor crimping or in a damp junction box will behave like a poor cable.

• Loose clamping screws or poor crimping

• Prolonged exposure of exposed copper to air (oxidation over time)

• Lack of cable strain relief (cable gradually stretches)

• Leaky outdoor junction boxes (water ingress)

3. Materials: What are OFC and OCC and what to choose in real PA projects

In fixed 70V/100V systems, material selection should be based on long-term performance stability, corrosion resistance, and total cost of ownership—not marketing hype. Below, we describe the actual meaning of the most common conductor types, how they are manufactured, and how they impact real-world PA installations.

Standard copper (electrical grade copper)

Most "standard" speaker cables use electrical-grade copper conductors, produced by drawing copper into strands and twisting them into a flexible core. The conductor can be stranded (made of many thin wires) for increased flexibility, then covered with insulation and an outer jacket. In 70V/100V PA systems, standard copper is typically the basic choice, as it offers a good balance of electrical conductivity, mechanical strength, and cost.

It is suitable for most indoor installations when properly sized. Differences in quality are primarily determined by the number of strands, the consistency of copper purity, and quality control during cable production.

OFC (oxygen-free copper)

OFC is still copper, but refined and processed to reduce oxygen and impurity levels. During cable production, OFC is typically drawn into strands in the same way as standard copper, but suppliers market it as a more stable copper with better purity control. Structurally, OFC cable is built using the same "recipe" as standard copper cable (stranded conductor + insulation + sheath); the difference lies in the copper grade and production controls.

The most significant advantage is batch-to-batch consistency and fewer unexpected issues in large projects. It does not replace proper cross-section selection. If the cross-section is insufficient, OFC will still exhibit voltage drop over distance.

Scope: long-term or large installations requiring consistent, repeatable cable quality; projects where cable is purchased in multiple batches over time.

OCC (Ohno continuous cast copper)

OCC is a copper casting process (production method), not a different metal. It is an improved version of OFC. The essence of OCC is to produce copper with very long crystal structures (fewer grain boundaries) compared to traditional casting. The conductor is then drawn and stranded like other copper cables and finished with insulation and a jacket.

OCC should be considered a premium option (for specifications/positioning), not a primary engineering tool.

Scope: premium positions or projects where the customer explicitly requests "OCC cable"; installations where the "highest-grade materials" narrative is required, while maintaining sound engineering principles.

Tinned copper (copper with a tin coating)

Tinned copper is copper with a thin tin coating on the surface of each strand. The core is still copper; the tin is primarily added to improve corrosion resistance and long-term stability of connections. In real-world installations, oxidation at exposed copper points and joints is a common cause of intermittent failures. Tinned copper reduces this risk, especially in humid or aggressive conditions.

It often provides greater real-world reliability gains than "premium copper grades," especially in outdoor and industrial applications. It helps reduce oxidation at connection points, especially when combined with proper sealing of junction boxes and cable strain relief.

Scope: Outdoor, coastal, and humid conditions; industrial facilities with temperature fluctuations or aggressive atmospheres; any facilities with exposed junction boxes and joints.

CCA (copper on aluminum base)

CCA is a composite conductor: an aluminum core with a thin copper coating on the outside. It is lighter and less expensive than copper. Its electrical and mechanical properties, when powered over long distances, are more similar to aluminum than copper: higher resistance for the same cross-sectional area and lower long-term stability under rough handling.

Higher resistance → greater voltage drop → distant speakers may sound weaker over long trunk lines. It is more sensitive to poor connections; the risk increases in outdoor and damp environments. When using CCA, it is generally necessary to increase the cable cross-sectional area and use conservative connected power ratings.

Scope: Short indoor lines with light loads and strict cost constraints. Not recommended for long trunk lines, harsh environments, or systems with difficult maintenance.

Table 1 - Loudspeaker Cable Materials (A Practical Look for PA)

A simple rule for most projects: choose copper/OFC as the default and treat OCC as an optional premium option rather than a requirement.

4. What Really Causes Cable Loss (and Why Some Lines Are "Not Balanced")

When clients complain about uneven volume across zones, the instinctive reaction is to keep adjusting the speaker taps. Sometimes this helps, but if the initial cable losses are too high, the problem will be endlessly pursued.

The main loss factors in 70V/100V PA system lines are:

• Long one-way distance to the farthest speaker

• High total connected power on a given line

• Insufficient cross-section of the main line feeding multiple speakers

• Too many splices and branches with inconsistent connection quality

• Outdoor lines with moisture penetration and corroded connectors

If it is necessary to power a powerful load over a long distance, increasing the cross-section of the main line helps, but splitting the line (or moving the amplifier closer to the load) is often a cleaner solution.

5. Selecting a cross-section for 70 V/100 V systems (simple and practical)

Most readers come to this article with one question: what speaker cable cross-section should I use? In distributed systems, informed decisions can be made without complex formulas, using three initial parameters: distance, total connected power, and operating margin.

Before choosing a section, determine these 3 parameters:

1. One-way distance to the furthest point of the line

2. Total connected power on the line (W)

3. Indoor or outdoor/aggressive (reserve)

Rule of thumb: 70V lines generally require slightly larger wire gauges than 100V lines for the same distance and load, since 70V has a higher current draw for the same power.

Use the table below as a starting point for copper conductors. For outdoor, hot, humid, or industrial applications, choose one size thicker.

Table 2 - Approximate selection of cross-section (copper, typical projects)

Increase the section by one size if the following conditions are met:

• Outdoor location or direct sunlight (UV/temperature fluctuations)

• Coastal/wet locations (risk of corrosion)

• Line powers multiple loudspeakers (high current on the first section)

• Higher paging clarity and power reserve required

Table 3 - AWG and mm² Conversion (Approx.)

6. A simple working algorithm for selection, applicable to any project

Once you master a repeatable algorithm, cable selection will no longer be subjective.

Practical algorithm (without calculations):

1. Divide the facility into logical lines (by enclosure/zone/direction)

2. Summarize the connected power (W) on each line.

3. Determine the maximum one-way distance for each line.

4. Select the cross-section using the quick table (for harsh environments, use a larger size).

5. Select the material/enclosure based on operating conditions (Table 1).

6. Make high-quality connections and seal the outdoor junction boxes.

7. Conclusion

A high-quality 70V/100V PA system depends on a stable power supply—and that's exactly what speaker cable provides. To ensure consistent volume across zones and fewer problems after commissioning, prioritize the following:

Line design: If possible, avoid a single, overloaded, long line.

Choose the wire gauge: Select the wire gauge based on the distance and total connected power, then add a reserve for harsh environments.

Material and installation quality: OFC for stability, OCC as an optional premium option; pay special attention to the jacket, sealing, and connections in outdoor areas.

By considering the wire gauge, material, and connection quality as a whole, your distributed system will ensure clear paging, balanced zones, and long-term reliability.