Unmatched Signal Purity. Limitless Application Potential.

The ARC Audio Cu 4.2 is a no-compromise 2-channel reference amplifier engineered to deliver the purest and most transparent sound available in mobile audio today. Designed by Robert Zeff and built around a next-generation Class A/B topology, the Cu 4.2 incorporates ARC’s exclusive technologies to set a new benchmark in amplifier design.

At its core is ARC’s ULF (Ultra-Low Feedback) system — an advanced signal architecture that eliminates harmonic and intermodulation distortion, revealing detail and nuance often lost in conventional amplifier circuits. Paired with TTB (Thermal Tracking Bias), a real-time bias management system that continuously adjusts for temperature and load conditions, the Cu 4.2 delivers consistent signal integrity and tonal accuracy under any demand.

For those who demand ultimate control, the Cu 4.2 includes a true front-end crossover bypass switch — an industry-first feature that completely removes all front-end signal processing from the circuit. This allows for a direct input-to-output path with the fewest components possible, delivering signal purity that purists will appreciate.

Whether you're bridging for subwoofer duty, bi-amping tweeters and mids, or running independent left/right channels for total separation, the Cu 4.2 offers flexibility without compromise. And when paired with ARC Audio’s Pro-Series DSPs, it becomes the cornerstone of a world-class audiophile system.

Finished in brushed copper and satin silver with gold-plated terminals and microprocessor-controlled cooling, the Cu 4.2 is every bit as refined in design as it is in performance. This isn’t just an amplifier — it’s a reference-grade tool for true music lovers.