Dayton Audio 3.5" ND91-4 Full-Range Neodymium Driver

Designed for engineers and DIY audio enthusiasts who need a true point-source driver in tight enclosures, the ND91-4 blends a rigid aluminum cone with a neodymium motor to reproduce from deep bass fundamentals up through detailed high frequencies. Its low distortion behavior and unusually large linear excursion for a 3.5" driver make it well suited for miniature monitors, surrounds, compact line arrays, and sealed or passive-radiator systems.

How does this driver perform across the frequency range?

The ND91-4 provides broad full-range output that reaches well into high frequencies while retaining usable low-end extension for its size. Expect clear mids and highs with a low resonance allowing smoother integration in small sealed or passive-radiator boxes.

• Nominal full-range response roughly 65 Hz to 17 kHz
• Aluminum alloy cone for controlled high-frequency dispersion
• Self-shielded motor minimizes magnetic interference in compact layouts

What allows this small driver to handle significant excursion?

This driver uses a large, long-travel motor and a robust voice coil assembly to achieve impressive linear stroke for its diameter. The underhung voice coil geometry combined with a compliant rubber surround keeps distortion low even near the excursion limits.

• 4.6 mm linear Xmax, 25 mm peak mechanical excursion capability
• 1" four-layer underhung voice coil on a polyimide former for heat resistance
• Rubber-edged surround for reliable cone excursion and damping

How does the motor and build reduce distortion and improve control?

The ND91-4 uses a neo-balanced magnet system with a copper-alloy shorting ring that reduces nonlinearities and improves transient response. The result is cleaner sound with less intermodulation at higher drive levels compared with simple ferrite designs.

• Neodymium magnet structure for compact, high-flux motor strength
• Copper-alloy shorting ring lowers electromagnetic distortion
• Self-shielded assembly for versatile placement near electronics

What enclosure types and configurations work best?

Because of its low-frequency reach and high excursion, the ND91-4 pairs well with small sealed cabinets or with matched passive radiators to extend bass without increasing box size. It also performs reliably in multi-driver arrays and compact nearfield monitors where the point-source characteristic is desired.

• Small sealed monitors and bookshelf speakers
• Surround channels and compact line-array designs
• Sealed boxes augmented by ND-series passive radiators for richer bass

Who is this for: The Dayton Audio ND91-4 suits hobbyists, speaker designers, and installers who need a compact full-range driver with exceptional excursion and low distortion. If you’re building miniature reference monitors, discreet surround speakers, or tight line-array modules and want controlled bass plus clear highs from a single small driver, this model is a practical, high-performance choice.