RDL ST-UMX3 3x1 Universal Audio MixerThe ST UMX3 is a three channel audio mixer for combining mic level or line level signals to a single output. A MIC LINE switch is provided for each input. A separate MIC LINE switch selects the output level. Each input features a separate preamplifier circuit, which isolates it from the other inputs. An audio taper single turn gain adjustment is provided for each of the three input preamps. Signals from the three preamps are actively summed and fed to