2 Channel Audio Meter-Average/Peak/Hold

Ideal Use Cases

The RDL RU-SM16A is a two-channel precision audio level meter for applications where one stereo signal or two mono signals must be observed. Its digital 16-LED string indication covers signal presence and calibrated level steps, supporting line-level paths, amplified speaker-level feeds, and distributed audio using 25, 70, or 100 V. Balanced and unbalanced inputs allow integration with either connection type.

• Monitoring the two channels of a stereo audio signal.
• Observing two independent mono audio paths with separate response settings.
• Checking line-level, low-impedance speaker-level, or constant-voltage amplifier outputs.

Why Choose This Model

The RU-SM16A combines multiple input-level options with individually configurable metering. Each channel can be switched independently between peak and average response, allowing two signals with different monitoring requirements to be displayed at the same time. Fixed or variable 0 dB calibration is switch-selectable, and individual channel calibration controls support separate adjustment of the two meters. Peak-hold indication at +10, +14, and +18 dB makes upper-level events easier to identify after they occur.

This flexibility makes the model useful when a single meter must accommodate more than one audio distribution format. Instead of being limited to line-level sources, it also accepts amplified speaker-level signals and 25/70/100 V audio inputs.

Installation and Integration

The RU-SM16A provides two inputs for line-level or amplified speaker-level audio. Input impedance is greater than 40 kΩ for balanced or unbalanced connections. Fixed calibration establishes a 0 dB reading at +4 dBu when the +4 setting is selected, or at 25 V, 70 V, or 100 V when the corresponding voltage setting is used. Variable calibration is also available for each selector position, including ranges of 2 V to 90 V at the 25 V setting, 4 V to 90 V at the 70 V setting, and 5 V to 100 V at the 100 V setting.

The specified speaker-level ranges apply to constant-voltage systems or low-impedance 4-Ohm and 8-Ohm amplifier outputs. Power requirements are a ground-referenced 24 Vdc at 250 mA. The recommended supplies are the PS-24AS for the USA and the PS-24AX for international use. The specified ambient operating range is 0 degrees C to 55 degrees C.

Performance Highlights

Metering frequency response extends from 20 Hz to 20 kHz. Each 16-position indication includes SIG, -20, -15, -12, -9, -6, -3, -2, -1, 0, +1.5, +3, +6, +10, +14, and +18. The +10, +14, and +18 positions are used as peak-hold indicators only.

Peak mode is configured for fast response, with a 50 us rise time from 10% to 90% and a 60 us rise time from 0% to 100%. Its specified fall times are 65 ms from 90% to 10% and 100 ms from 100% to 0%. Average mode has a 130 ms rise time from 10% to 90%, a 300 ms rise time from 0% to 100% with VU characteristic, a 185 ms fall time from 90% to 10%, and a 300 ms fall time from 100% to 0% with VU characteristic.

What Makes It Different

The defining feature of the RU-SM16A is the combination of two-channel metering, broad input compatibility, and per-channel configuration. It can function as a stereo meter or as two mono meters without restricting both channels to the same response mode. One channel can use peak response while the other uses average response. Selectable fixed or variable calibration further adapts each meter to the connected signal level, while the three peak-hold positions provide a persistent indication of the highest listed levels.

Final Assessment

The RDL RU-SM16A is a focused solution for precision two-channel audio level monitoring across line-level, speaker-level, and 25/70/100 V systems. Its 20 Hz to 20 kHz metering response, 16-position indication, independent peak or average selection, individual calibration controls, and +10, +14, and +18 dB peak hold provide concrete monitoring capabilities for stereo and dual-mono audio paths.