The RU-SM16D is the ideal choice in most applications where the metering of multiple audio levels is to be designed into a system or added to existing equipment. The RU-SM16D has four separate inputs. Each input may be individually calibrated for unbalanced consumer, balanced professional, 8 Ohm speaker line or constant voltage speaker lines (25 V, 70 V or 100 V). All connections are made using detachable terminal blocks. A rear-panel switch selects variable or fixed calibration for 25V, 70V, 100V and +4 dBu sources. In the "variable" position, front-panel multi-turn trimmers adjust the calibrated meter levels. Rear-panel switches 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 two meters, setting one for peak and the other for average. In either mode the upper three LEDs (+10, +14, +18) remain in the PEAK HOLD mode. In stereo applications, each channel, left and right, can display both peak and average values. Each of the four meters in the RU-SM16D may be operated separately to monitor four different sources. The RU-SM16D uses bright LEDs for good visibility. Each input has a label area for identification of the source or function being metered.