3.5 Watt Audio Power and Headphone Amplifier-SS

The RDL DS-HPA3 is an ultra-compact, wall-mounted audio amplifier that combines a speaker power amplifier and a headphone amplifier in an all-metal enclosure. It accepts a 20 kΩ balanced or unbalanced bridging input and provides a rear-panel speaker output plus a front-panel mini-jack headphone output. High-efficiency Class D operation, shared gain adjustment, configurable speaker muting, and built-in protection make it a focused solution for installations requiring both personal and loudspeaker listening.

Ideal Use Cases

The DS-HPA3 is suited to wall-mounted audio systems that need one input to serve both a local speaker and headphones. Its speaker amplifier delivers up to 3.5 W RMS into 8 ohms or 6.5 W RMS into 4 ohms, allowing it to drive either a 4-ohm or 8-ohm speaker. The separate headphone output provides 10 mW into 100 ohms during normal operation and up to 30 mW into 100 ohms. A setting can turn off the speaker power amplifier when headphones are connected, supporting installations where headphone listening should replace rather than accompany speaker playback.

Why Choose This Model

This model places its primary connections where they are practical for a wall-mounted installation. The balanced input and speaker output are located on the rear panel, while the mini-jack headphone connection and single-turn audio-taper gain adjustment are accessible from the front. One gain control adjusts both the speaker and headphone amplifiers, keeping operation straightforward. The speaker connection uses a detachable terminal block, and the unit supports balanced or unbalanced input wiring. Its compact all-metal construction measures 4.13 inches high, 1.7 inches wide, and 2.05 inches deep.

Installation and Integration

The DS-HPA3 uses a 20 kΩ balanced or unbalanced bridging input. Its nominal input levels are +4 dBu for a balanced connection with low input sensitivity and -15 dBV for an unbalanced connection with high input sensitivity. Maximum input level is +22 dBu at low sensitivity or +4 dBu at high sensitivity. The amplifier requires 24 Vdc and draws 30 mA while idle, 55 mA at one-eighth power with normal voice or music, and 225 mA when delivering 3.5 W into 8 ohms. Recommended power supplies are the PS-24AS for the USA and PS-24AX for international use.

Performance Highlights

The headphone path has a frequency response of 20 Hz to 50 kHz within ±1 dB, while the speaker path covers 20 Hz to 20 kHz within ±1 dB. Headphone THD+N is less than 0.1% from 20 Hz to 20 kHz at 10 mW into 100 ohms. Speaker THD+N is also less than 0.1% at 1 kHz and 1 W. Headphone noise is below -85 dB relative to 10 mW into 100 ohms, and speaker noise is below -80 dB relative to 1 W into 8 ohms. Common-mode rejection exceeds 50 dB from 50 Hz to 120 Hz.

What Makes It Different

The DS-HPA3 integrates two output types into one narrow wall-mounted device without separating their everyday level control. Its solid-state switching provides amplifier muting, and the headphone-detection setting can disable the speaker power amplifier when a headphone plug is inserted. High-efficiency Class D operation supports the speaker output, while thermal and short-circuit protection help protect the amplifier during operation. The combination of rear-panel permanent wiring, a detachable speaker terminal block, and a front-accessible headphone jack keeps fixed installation connections separated from the controls and connection used by the listener.

Final Assessment

The RDL DS-HPA3 is a specialized speaker and headphone amplifier for installations where compact wall mounting, balanced or unbalanced input compatibility, and direct access to headphone listening are required. It supplies up to 6.5 W RMS into 4 ohms or 3.5 W RMS into 8 ohms, offers one front-panel gain adjustment for both amplifiers, and can mute speaker operation when headphones are connected. Its all-metal construction, Class D speaker amplification, detachable output connector, and thermal and short-circuit protection provide a concise set of installation-focused features.