3.5 Watt Audio Power and Headphone Amplifier

The RDL D-HPA3 is a wall-mounted audio power and headphone amplifier designed around two directly accessible outputs. A rear-panel speaker output drives either a 4- or 8-ohm speaker, while a front-panel mini-jack serves headphones. Its high-efficiency Class D power stage delivers up to 3.5 W RMS into 8 ohms or 6.5 W RMS into 4 ohms. An ultra-compact all-metal enclosure, shared gain control, configurable speaker shutdown during headphone connection, and integrated protection bring the core signal, control, and output functions into one compact unit.

Ideal Use Cases

The D-HPA3 fits wall-mounted installations that require both local speaker amplification and convenient headphone access. It is especially useful when the speaker and headphone outputs need to share one input and one gain setting. Rear-panel input and speaker connections keep fixed wiring behind the unit, while the front mini-jack makes the headphone output readily accessible. Its 20 kΩ bridging input accommodates balanced or unbalanced sources, and the speaker amplifier supports either 4- or 8-ohm loads.

Why Choose This Model

This model combines two output functions without requiring separate gain adjustments for the speaker and headphone amplifiers. A single-turn, front-panel audio-taper control manages gain for both outputs. The D-HPA3 also provides a setting that turns off the power amplifier when headphones are connected, allowing the speaker output to be silenced as part of the headphone connection behavior. Amplifier muting uses solid-state switching, while thermal and short-circuit protection safeguard the amplifier during operation.

Installation and Integration

The rear-panel input supports 20 kΩ balanced or unbalanced bridging. Nominal input levels are +4 dBu for a balanced connection at low input sensitivity and -15 dBV for an unbalanced connection at high input sensitivity. Maximum input level is +22 dBu at low sensitivity or +4 dBu at high sensitivity. The speaker output uses a detachable terminal block for easier connection and service access. The enclosure measures 4.13 inches high by 1.7 inches wide by 2.05 inches deep, equivalent to 10.49 by 4.32 by 5.21 cm. Power is supplied at 24 Vdc. Recommended supplies are the PS-24AS for the USA and PS-24AX for international use; the power supply is not included. The specified operating environment is 0°C to 40°C maximum, with 20°C recommended.

Performance Highlights

The speaker amplifier produces a maximum of 3.5 W RMS into 8 ohms and 6.5 W RMS into 4 ohms. Headphone output is rated at 10 mW into 100 ohms during normal operation and 30 mW into 100 ohms maximum. Headphone frequency response extends from 20 Hz to 50 kHz within ±1 dB, while speaker response covers 20 Hz to 20 kHz within ±1 dB. Headphone THD+N is specified below 0.1% from 20 Hz to 20 kHz at 10 mW into 100 ohms. Speaker THD+N is also below 0.1% at 1 kHz and 1 W. Noise is below -85 dB for the headphone output below 10 mW into 100 ohms and below -80 dB for the speaker output below 1 W into 8 ohms. CMRR is greater than 50 dB from 50 Hz to 120 Hz.

What Makes It Different

The D-HPA3 places its headphone connection and shared gain adjustment on the front while retaining the balanced input and detachable speaker connection on the rear. This layout separates user-accessible controls from fixed installation wiring. The selectable power-amplifier shutdown behavior provides a direct way to coordinate headphone and speaker operation. High-efficiency Class D amplification, solid-state muting, an all-metal enclosure, and protection against thermal and short-circuit conditions complete a feature set focused on compact integration.

Final Assessment

The RDL D-HPA3 is a focused solution for installations needing a wall-mounted speaker amplifier and front-accessible headphone output in one ultra-compact enclosure. It supports balanced or unbalanced input wiring, 4- or 8-ohm speakers, unified gain adjustment, and configurable speaker shutdown when headphones are connected. With documented audio performance, detachable speaker wiring, Class D operation, and built-in protection, it provides a clearly specified combination of speaker and headphone amplification.