Radio Design Labs RU-SM16
Dual Channel Audio Meter

RU-SM16

The RU-SM16 is the ideal choice in most applications where audio-level metering needs to be designed into a system, or added to existing equipment. All connections are made using full-size barrier block terminals on the rear panel.

The RU-SM16 has two separate line-level inputs. Each of the inputs permits the connection of either balanced or unbalanced, high or low impedance audio lines.

When a stereo source is used, one channel is connected to each of the two inputs. In this configuration, the RU-SM16 provides a separate display for each of the inputs. The level calibration reference is user adjustable by a 25-turn trimming potentiometer available through the front panel. Unlike meters that use an off-the-shelf chip, the RU-SM16 develops a single precision reference for each metering increment. Comparators are used to switch the LEDs in the string display, with the respective comparators for each channel connected to the same reference. Therefore, when the input calibration controls are set equally, each channel’s LED for a given dB value will switch on at exactly the same audio signal level. The metering sample is derived from an active, precision full-wave rectification circuit. Isolation between channels is amply sufficient to use the RU-SM16 to meter two monaural signals simultaneously.

Jumpers on the rear panel allow the installer to set each meter individually for either peak or average audio level display. In monaural installations, it may be advantageous to feed the mono source to both meters, setting one for peak and the other for average. In either mode the upper three LEDs (+10, +14, and +18) remain in the peak-hold mode. These LEDs illuminate at the peak rate and remain illuminated about one-half second to provide a clear visual indication of levels which impact system headroom.

The peak mode response time is nearly instantaneous with a dwell time sufficient to eliminate pulsing of the display, thereby giving the user an accurate visual representation of peak excursions. The average mode features rise and fall times providing the user with visual VU metering ballistics.

The RU-SM16 uses bright LEDs for good visibility. Each of the channel inputs has a write-on label area for identification of the source or function being metered.

Specifications:

• Inputs (2): Line-level
• Input Impedance: 200 kohm balanced or unbalanced
• Input Range (sensitivity): -26 dBu to +14 dBu (for 0 dB reading)
• Metering Freq. Resp.: 20 Hz - 50 kHz
• Indicators: 16 LEDs per channel; -20, -15, -12, -9, -6, -3, -2, -1, 0, +1.5, +3, +6, +10, +14, +18 (+10, +14, +18 are peak-hold indicators only)
• Metering Response: Each channel individually selectable PEAK or AVERAGE (terminal block strap provided)
• Power Requirement: 24 to 33 Vdc @ 250 mA, Ground-Referenced

Our Part #  RUSM16