Audio Mixer / Distribution Amplifier

Ideal Use Cases

The RDL TX-MX2R is designed for installations that need to mix two unbalanced mono signals or combine the left and right channels of a stereo source into mono. Each input has its own gain adjustment, making the unit suitable when two source levels must be matched before they are combined. The resulting signal is available from two active isolated outputs, allowing the mixed audio to feed two unbalanced lines. The outputs are specified to drive either low- or high-impedance unbalanced inputs.

This model is also appropriate when isolation between two connected inputs is important. Its focused feature set addresses source combining, level trimming, stereo-to-mono conversion, and dual-output distribution without adding unrelated processing functions.

Why Choose This Model

The TX-MX2R combines mixing and distribution functions in one audio module. It accepts two unbalanced inputs, provides adjustable gain for each channel, and supplies two active isolated outputs from the combined input signal. Gain is adjustable from unity to a nominal +6 dB per channel, providing a defined range for matching source levels.

Isolation between the inputs helps keep the two connected sources separated before they are mixed. The two active outputs provide a practical way to distribute the resulting mono signal without relying on a passive split. Both outputs have a 100 Ω unbalanced configuration and deliver a specified -10 dBV level for connection to low- or high-impedance unbalanced lines.

Installation and Integration

The unit requires a ground-referenced DC supply from 12 to 33 Vdc and draws 10 mA. A power supply is not included. The listed recommended supplies are the PS-24AS for use in the USA and the PS-24AX for international use. Installers should select an appropriate supply and observe the stated ground-referenced power requirement.

The two inputs are listed at 10 dBV with a 10 kΩ input impedance. Each input includes a gain trim, so connected sources can be adjusted individually from unity through +6 dB nominal gain. After the sources are combined, the signal is delivered to both active isolated outputs. The specified ambient operating range is 0°C to 55°C. Package dimensions are 2 x 2 x 4 inches, with a shipping weight of 0.26 pounds.

Performance Highlights

The TX-MX2R is specified for high-quality unbalanced audio with a frequency response of 25 Hz to 45 kHz within ±0.5 dB. Its extended response is listed as 15 Hz to 70 kHz within ±1 dB. Noise is specified at less than -75 dB when referenced to -10 dBV.

Total harmonic distortion plus noise is less than 0.05%, with 0.01% listed as typical. Intermodulation distortion is also specified at 0.01% typical. Available headroom depends on the supply voltage: greater than 27 dB with a 24 Vdc supply and greater than 18 dB with a 12 Vdc supply.

• Two unbalanced inputs with 10 kΩ input impedance
• Unity to +6 dB nominal adjustable gain per channel
• Two active isolated 100 Ω unbalanced outputs
• -10 dBV output for low- or high-impedance unbalanced lines
• Less than 0.05% THD+N, with 0.01% typical
• 0.01% typical IMD

What Makes It Different

The defining feature of the TX-MX2R is its combination of two-input mixing, stereo-to-mono conversion, input isolation, individual gain trimming, and two active isolated outputs. Instead of only combining two sources, it also distributes the resulting signal to two destinations. Instead of providing a fixed mix, it allows each input to be adjusted independently within the stated gain range.

Its wide specified frequency response, low typical distortion figures, and voltage-dependent headroom ratings provide clearly documented performance parameters. Compatibility with a broad 12 to 33 Vdc supply range also gives integrators multiple supported power options, provided the supply is ground-referenced.

Final Assessment

The RDL TX-MX2R is a purpose-built audio mixer and distribution amplifier for two unbalanced sources. It can mix two mono signals, convert stereo to mono, trim the gain of each input, and send the combined audio through two active isolated outputs. With documented response, noise, distortion, headroom, impedance, and power specifications, it provides a well-defined solution for unbalanced audio combining and dual-line distribution.