Hertz DP 4.400 4-Channel Class AB Car Amplifier

The Hertz DP 4.400 is a four-channel Class AB car amplifier designed to add clean, configurable power to factory or aftermarket audio systems. It provides 75 watts RMS to each of four channels at 4 ohms, making it well suited to powering upgraded front and rear speakers. Its bridgeable design also allows it to support systems that combine stereo speakers with higher-power channels.

This amplifier is a practical option for listeners who want greater output and control than a head unit can provide without moving to a large amplifier chassis. It is stable down to 2 ohms per channel in four-channel operation and can be configured for four-, three-, or two-channel use. That flexibility supports a range of speaker layouts as a system grows.

The DP 4.400 uses a Class AB output stage with a specified 10 Hz to 45 kHz bandwidth at -3 dB, along with Hi-Res Audio certification covering 10 Hz to 50 kHz. Its 0.01% THD specification at 100 Hz and 70% rated power, 101 dBA signal-to-noise ratio, and balanced input circuitry are intended to support low-noise signal transfer. The result is an amplifier built for detailed full-range speaker amplification rather than subwoofer-only duty.

Installation options include RCA preamp inputs for aftermarket radios and speaker-level inputs for integration with many OEM systems. The built-in Universal Speaker Simulator helps maintain compatibility with source units that monitor speaker load, while ART automatic remote turn-on can activate the amplifier from compatible BTL speaker-level signals. A full-range front pre-out can also feed an additional amplifier.

Independent front and rear high-pass and low-pass filter sections allow the DP 4.400 to be tailored for full-range speakers, component systems, or mixed amplified systems. Each filter section adjusts from 50 Hz to 4,000 Hz with a 12 dB/octave slope, and the rear section includes selectable 50 Hz bass boost. Its compact footprint, protected controls, and solid terminal arrangement make it a capable foundation for a carefully planned vehicle audio upgrade.

Key Features

• Four-Channel Class AB Power: Delivers 75 watts RMS per channel at 4 ohms.
• 2-Ohm Stable Outputs: Supports 105 watts RMS per channel at 2 ohms.
• Bridgeable Channel Design: Provides up to 210 watts RMS per bridged pair.
• Hi-Res Audio Certified: Supports a certified 10 Hz to 50 kHz response range.
• OEM and Aftermarket Inputs: Includes RCA pre-in and speaker-level input connections.
• Adjustable Crossovers: High- and low-pass filters help match speakers and system roles.

Design & Installation

The DP 4.400 uses a compact chassis with a removable top panel that protects its controls and connections. It features a status LED and machined terminal blocks for power and speaker wiring. The amplifier measures 335 x 190 x 50 mm and weighs 2.88 kg.

Use RCA pre-in connections with an aftermarket head unit, or use the speaker-level inputs when retaining a compatible factory radio. Configure each channel pair with its level control and high-pass, low-pass, or full-range setting before finalizing speaker wiring. For bridged operation, use 4-ohm speaker loads and follow the terminal markings and instructions in the supplied documentation.