[Graphic] The Master Volume Knob, in the Master Panel, affects the ouput of all LoopTracks. Turn it down all the way to mute jambient, set it to full to let LoopTracks play at full volume.
If you have a joystick attached, by default the throttle controls Master Volume--full throttle turns it all the way up, no throttle mutes. When a joystick is controlling the Master Volume, you cannot control it with the mouse, unless you select "None" for the axis that controls Master Volume. (To choose how the joystick controls Master Volume, see Options.)
If you have no joystick, or the joystick options are set so that the Master Volume Knob is not under joystick control, the Master Volume Knob is dialled just like other Volume Knobs.