35 Watt Remote Mixer Amplifier-4/8 Ohm Outputs

Ideal Use Cases

The RDL HD-RA35U is designed for audio systems that combine background music, paging, and music-on-hold. Its two-zone architecture provides a 35 W RMS main zone and a separate 4 W RMS zone 2 at 8 ohms. The main zone is a remote-controlled mixer with three user controls, while zone 2 uses four rear-panel level trimmers for inputs 1 through 4. Input 1 has a dedicated front-panel paging level, and inputs 2, 3, and 4 support compatible RDL VCA wall controls through an RJ45, 0 to 10 VDC control interface.

When announcements must take priority, Input 1 can trigger automatic VOX ducking through an adjustable rear-panel threshold, or priority can be actuated manually by contact closure to ground. Inputs 2, 3, and 4 can be selected independently for nominal 25 dB ducking, and the release delay adjusts from 2 to 6 seconds. This control layout supports systems that alternate between continuous program audio and priority speech.

Why Choose This Model

Two balanced channels can each be switched between mic and line operation and connect on terminal blocks. Each mic input also provides individually switch-selectable 24 VDC phantom voltage. Two unbalanced stereo-summing inputs use RCA jacks, and a separate unbalanced amplifier input is provided on RCA. Rear-panel gain trimmers set inputs 1 and 2, while the three VCA channels handle main-zone levels for inputs 2 through 4. Front-panel bass and treble controls provide ±10 dB at 10 kHz and ±9 dB at 100 Hz, with center detents. A built-in compressor operates with a threshold 2 dB below rated output and automatically adjusts attack and release times.

Installation and Integration

Balanced inputs and amplified outputs use detachable terminal blocks, while unbalanced inputs and outputs use RCA jacks. The effects loop exposes the main mixer’s preamp output and power-amplifier input on RCA connections and includes a bypass switch. The main mixer also provides dual-mono unbalanced RCA line outputs with rear-panel flat or equalized selection, while the zone 2 mixer has a balanced terminal-block output. A dedicated music-on-hold output is rated at 0 dBu nominal into 600 ohms, is transformer-isolated, and provides 16 dB of headroom. An auxiliary 24 VDC, 100 mA output can power an external RDL module. The included supply accepts 100 to 240 VAC at 50-60 Hz and supplies 24 VDC to the amplifier chassis. The chassis measures 3.5 inches high, 8.5 inches wide, and 10 inches deep, with a weight of 5.6 pounds.

Performance Highlights

Mixer frequency response is specified at ±1.5 dB from 40 Hz to 25 kHz for mic-to-line operation, ±1 dB from 20 Hz to 20 kHz for balanced line inputs, and ±0.5 dB from 20 Hz to 20 kHz for unbalanced line inputs. Amplifier response is ±1 dB from 50 Hz to 20 kHz. THD+N is less than 0.5% at 1 kHz at the compressor threshold through the main amplifier output and less than 0.1% through the main line output. Mic-input CMRR exceeds 50 dB from 50 Hz to 120 Hz, while the transformer-coupled balanced line inputs exceed 80 dB across the same range. Maximum input levels are -9 dBu for mic, +20 dBu for balanced line, and +5 dBV for unbalanced sources, with one unbalanced input supporting +11 dBV, measured for 1% THD+N at the output.

What Makes It Different

In automatic sleep mode, the amplifier and included power supply consume less than 1 W. The standby delay is selectable from 10 minutes to 2 hours in 10-minute increments, and sleep mode can be disabled. After input audio is detected, the nominal active-mode delay is 2 seconds. The stated efficiency standard is Energy Star Program Requirements for Audio/Video Version 2.0, applicable to passive remote-control models without muting. Front-panel indicators show signal presence for all four inputs, compressor activity, and power or standby status. Rear-panel indicators provide a dual-LED VU display for inputs 1 and 2 and a yellow ducking-threshold indicator. Additional routing controls include paging bypass for the tone controls, pre- or post-EQ line-output selection, and effects-loop bypass.

Final Assessment

The HD-RA35U consolidates priority paging, remotely adjustable program levels, a secondary local mix, music-on-hold, tone control, compression, and automatic standby in one chassis. It is best matched to systems that can use its 35 W main zone, 4 W RMS zone 2 output at 8 ohms, 4/8-ohm output arrangement, and RDL-compatible VCA controls. Detachable balanced connections, RCA integration points, selectable ducking, and the included universal power supply give installers clearly defined options for configuring both source routing and day-to-day operation.