Hertz ST25ANEO-2 1.8" Compression Tweeters

The Hertz ST25ANEO-2 is a pair of compact 44 mm (1.8-inch) high-efficiency compression tweeters for car-audio systems. It is designed to add focused upper-frequency output where conventional full-range speakers or midranges need dedicated treble support. The ST 25A NEO active-version design supplies the tweeters themselves for use in a properly configured active or filtered system.

With a 3 kHz to 20 kHz frequency-response specification and 107 dB SPL sensitivity, these tweeters are intended for systems that prioritize high-frequency presence and output. Their aluminum dome is lightweight for responsive high-frequency reproduction. A 4-ohm nominal impedance supports matching with compatible car-audio amplification and crossover networks.

The ST25ANEO-2 uses a 25 mm CCAR copper-clad aluminum ribbon voice coil and a neodymium motor. Hertz specifies N38 H neodymium for the motor assembly, helping keep the driver compact and light. The compression-driver format also incorporates a phase plug and loading horn optimized using FEM design methods.

Hertz rates each tweeter for 100 watts peak when it is high-pass filtered at 5 kHz with a 12 dB-per-octave slope. This filter requirement is important: the tweeters should not be connected directly to a full-range signal. A suitable active crossover, DSP, or passive high-pass network is needed to limit low-frequency energy.

The compact housing uses high-current screw terminals for speaker-wire connection and includes body waterproofing with anti-UV treatment. Its published dimensions should be checked against the intended custom panel, pod, or mounting location before installation. These tweeters are a practical match for an SPL-oriented multi-driver build that needs dedicated high-frequency drivers.

Key Features

• 44 mm Compression Driver: Compact high-efficiency tweeter format for dedicated high-frequency output.
• 100 W Peak Handling: Rated with a 5 kHz, 12 dB-per-octave high-pass filter.
• 107 dB SPL Sensitivity: Supports strong output with comparatively modest amplifier power.
• N38 H Neodymium Motor: Provides a compact magnetic motor assembly.
• Aluminum Dome: Lightweight diaphragm material for upper-frequency reproduction.
• CCAR Voice Coil: Copper-clad aluminum ribbon coil supports thermal and mechanical capability.

Design & Installation

The ST25ANEO-2 combines an aluminum dome, CCAR voice coil, neodymium magnet, and FEM-optimized phase plug/loading horn. Hertz also specifies body waterproofing and anti-UV treatment, along with high-current screw terminals. Each component weighs 0.39 kg (0.86 lb).

Use these tweeters as part of a filtered system, with a high-pass point at 5 kHz and a 12 dB-per-octave slope specified for the peak-power rating. Confirm the 57 mm, 43.5 mm, 55.5 mm, and 29.7 mm published dimensional references against the planned installation location. Pair them with compatible 4-ohm amplification, an active crossover or DSP, and suitable midrange drivers for a complete system.