When designing an AV system, one of the most important decisions is choosing between 8-ohm speakers and 70V distributed audio systems. Each has its own strengths, ideal use cases, and trade-offs. Understanding the difference can save you time, money, and future headaches.

What’s the Difference?

8-ohm speakers are commonly used in residential and high-fidelity audio applications. Each speaker operates as an individual load, and amplifier power is divided among them based on wiring topology.

70V systems, also known as constant voltage systems, are used in commercial and large-scale environments. They allow multiple speakers to be daisy-chained together over long distances using smaller-gauge wire, thanks to internal transformers.

Pros and Cons of 8 Ohm Speakers

✅ Pros:

• High-quality sound: Typically offer better frequency response and dynamic range—ideal for music playback and critical listening.

• Direct connection: No transformers to color the sound or add complexity.

• Power matching: Works well with most consumer and commercial amplifiers.

⚠️ Cons:

• Wiring limitations: Longer cable runs cause signal loss unless thick (expensive) cables are used.

• Limited speaker count: You’re often restricted to 1-2 speakers per amplifier channel without overloading.

• Complex impedance math: Requires careful design to avoid overloading the amp with too low of a total impedance.

Best Use Cases:

• Conference rooms

• Home theaters

• Auditoriums with fewer speakers

Pros and Cons of 70V Speakers

✅ Pros:

• Scalability: Connect dozens (or even hundreds) of speakers to a single amplifier.

• Simple wiring: Daisy-chain speakers with lightweight cable and long runs.

• Flexible volume control: Use tap settings or in-line attenuators to set different levels per zone.

⚠️ Cons:

• Reduced audio fidelity: Transformers may limit bass response and dynamic range.

• Initial setup requires planning: You need to budget total wattage and tap settings to match the amplifier.

• Less suitable for high-power applications: Not ideal for subwoofers or full-range high SPL systems.

Best Use Cases:

• Offices and warehouses

• Hotels, restaurants, and retail stores

• Campus-wide paging and background music

Which Should You Use?

If you're installing a high-quality sound system for a controlled space like a conference room or theater, 8-ohm speakers give you better sound and more control. But if you’re covering large areas like hallways, campuses, or multiple rooms with background audio or paging, 70V is the way to go.

Need Help Designing Your System?

At Black Mountain Technologies, we specialize in designing audio systems that work right the first time. Whether you need pristine sound in a boardroom or reliable coverage across a school or facility, we’ll help you choose the right architecture and document everything for a smooth install.

📞 Contact us today to get started with your AV project.