Remote Controlled Line-Level Mixer

The RDL FP-MX3R is a three-channel remote-controlled audio mixer for line-level sources. Each input uses VCA level control and accepts balanced or unbalanced signals, while the output section provides a 150 Ω balanced output plus two 1 kΩ unbalanced mono outputs on RCA phono jacks. Front-panel gain trim, output metering, and audio-presence detection combine source control, monitoring, and system-power support in one unit.

Ideal Use Cases

The FP-MX3R fits audio systems that need up to three line-level inputs controlled away from the mixer. It connects directly to RDL two- or three-channel remote controls over twisted pair. When a two-channel remote is used, input 3 can operate at a fixed level, allowing it to accommodate a paging source while the other two inputs remain remotely adjustable. The two mono unbalanced outputs can feed a stereo amplifier, while the balanced output serves equipment using a +4 dBu line level.

Why Choose This Model

Independent VCA control for every input provides more than 90 dB of attenuation per channel when the remote-control volume is off. Balanced or unbalanced input compatibility makes the mixer adaptable to different line-level sources without limiting all connections to one format. Inputs use detachable terminal blocks, the balanced output uses a detachable terminal block, and the unbalanced outputs use RCA phono jacks. A front-panel gain trim accommodates standard audio line levels and allows the input signal range to be adjusted for a +4 dBu output.

Installation and Integration

The chassis measures 1.42 inches high, 3.25 inches wide, and 8.14 inches long. Remote-control communication uses twisted-pair wiring, supporting direct integration with compatible two- or three-channel RDL remote controls. Power can connect through a terminal block or either of two DC power jacks. The mixer requires 24 Vdc at 120 mA, plus any connected control-output loads. Recommended power supplies are the PS-24AS for the USA and PS-24AX for international use; the power supply is not included. The specified adjustable input range is 20 dBV to +8 dBu for a +4 dBu output.

Performance Highlights

Frequency response extends from 20 Hz to 20 kHz within ±0.25 dB. THD+N is specified at less than 0.05% from 20 Hz to 20 kHz and less than 0.02% at 1 kHz. Noise below a +4 dBu output is less than -100 dB with all channels off, less than -75 dB with any channel on, and less than -70 dB with all channels on. The mixer provides more than 18 dB of headroom above +4 dBu and greater than 50 dB CMRR from 50 Hz to 150 Hz. Output levels are +4 dBu balanced and -10 dBV unbalanced.

What Makes It Different

Beyond remote mixing, the FP-MX3R includes an audio-presence detector that controls open-collector outputs. These detector outputs are intended to enable power amplifiers or system power, creating the possibility of energy savings when connected equipment does not need to remain continuously enabled. The detector threshold is 35 dB below the +4 dBu output level, and its release delay can be set to either 10 or 20 minutes. A dual-LED VU meter displays mixer output level, while an audio-present indication provides an additional view of signal status.

Final Assessment

The FP-MX3R brings together three-channel line-level mixing, per-input VCA control, remote operation, balanced and unbalanced connectivity, and signal-triggered control outputs. It is particularly well matched to configurations that combine two remotely adjusted sources with a fixed-level third source, including a paging feed. Its balanced +4 dBu output, dual mono -10 dBV outputs, detachable connections, detailed output metering, and selectable detector delay provide a clearly defined set of integration options. A separate 24 Vdc power supply is required.