RDL TX-LC Unbalanced to Balanced Line Co

Ideal Use Cases

The RDL TX-LC2 is designed for applications that need to mix two unbalanced audio signals into one mono balanced output. It can combine the two channels of a stereo source into mono while providing the balanced output required by the next device in the signal path. The 150 Ω output is specified to drive low- or high-impedance inputs and may feed balanced or unbalanced lines. This makes the TX-LC2 suitable when the source format, channel configuration, and destination format do not otherwise match. Its two inputs are rated at 10 dBV nominal and -22 dBV minimum, with a 10 kΩ input impedance.

Why Choose This Model

The TX-LC2 combines four clearly defined functions: two-input mixing, stereo-to-mono combining, unbalanced-to-balanced conversion, and adjustable output gain. Isolation between the inputs allows the two signals to remain isolated before they are combined. The output gain trim provides ±10 dB of adjustment relative to a +4 dBu balanced output, giving the installer control over the delivered level. Instead of providing conversion alone, the unit also resolves the need to combine two channels into a single mono feed. Its published audio specifications include low THD+N, more than 18 dB of headroom, and frequency response extending to 20 kHz.

Installation and Integration

Connect the two unbalanced audio sources to the TX-LC2 inputs, route the mono output to the receiving line, and use the output gain trim to set the required output level. The balanced output is rated at +4 dBu and can drive low- or high-impedance destinations on balanced or unbalanced lines. The unit requires a ground-referenced 24 Vdc supply at 30 mA. Recommended power supplies are the PS-24AS for the USA and the PS-24AX for international use; the power supply is not included. The compact enclosure measures 1.4 inches high, 3.0 inches long, and 1.2 inches wide, equivalent to 3.6 by 7.6 by 3.0 cm. The specified ambient operating range is 0 degrees C to 55 degrees C.

Performance Highlights

The TX-LC2 has a frequency response of 10 Hz to 20 kHz within ±0.25 dB when feeding a bridging input. When driving 600 Ω, the specified response is 25 Hz to 20 kHz within ±0.25 dB. Noise is listed at less than -85 dB below +4 dBu with a -10 dBV input and 12 dB of gain. THD+N is specified at less than 0.005%, while the published IMD specification is greater than 0.001%. Output gain is adjustable across ±10 dB relative to the +4 dBu balanced output, and available headroom is greater than 18 dB. Together, these specifications define the unit’s operating bandwidth, level range, and distortion performance for line-level audio integration.

What Makes It Different

The defining feature of the TX-LC2 is the way it combines two signal-management tasks in one compact device. It does not simply convert an unbalanced signal to balanced; it accepts two unbalanced inputs, maintains isolation between them, and produces a mono output. That arrangement directly supports stereo-to-mono conversion without omitting the balanced line interface. The adjustable gain stage further distinguishes the signal path by allowing output-level trimming around the specified +4 dBu reference. Its 150 Ω output also supports connection to both low- and high-impedance lines, whether the destination is balanced or unbalanced.

Final Assessment

The RDL TX-LC2 is a focused choice for combining two unbalanced audio channels and delivering the result as a mono balanced signal. Its input isolation, ±10 dB gain adjustment, +4 dBu output, and published 10 Hz to 20 kHz response into a bridging input provide concrete parameters for system planning. The small enclosure can be incorporated where space is limited, while the 24 Vdc, 30 mA requirement establishes a modest and clearly documented power need. For an installation requiring stereo-to-mono mixing and unbalanced-to-balanced conversion in the same signal path, the TX-LC2 provides both functions in a single model.