User manual RANE FPS 28

[. . . ] The switches which determine this are located within the confines of the unit's covers. All FPS 28s are shipped from the factory with the switches in the POST fader position. Once inputs and outputs are satisfactorily connected, set the input gains as high as possible without causing the A and B overload indicators to illuminate steadily with very high input levels. If 1 x 8 splitter operation is required, only one input is used and the STEREO / MONO switch should be in the MONO position. [. . . ] In the STEREO mode, Input A drives bus A only; Input B connects to bus B only. 6. Each pair of output controls sets the individual channel output levels. The inner knob is for channel A, the outer is channel B. 7. When this yellow LED is illuminated, the foregoing information should be correct. If darkness is present at this location, most or all of the above will be inoperative. REAR PANEL DESCRIPTION 1. Use these 3-pin input connectors for either microphone or line level inputs to be split by the FPS 28. Connect balanced sources to the respective "+", "­" and "GND" pins which are pins 2, 3 and 1 respectively. Unbalanced inputs should connect to pins 2 and 1 only. When using an unbalanced input, pin 3 may be left open or shorted to "GND". These two tip-ring-sleeve 1/4" jacks directly parallel pins 1, 2 and 3 of the three pin input connectors. The tip is connected to pin 2, the ring goes to pin 3 and sleeve jumpers to pin 1. These are to be used in situations where more than a stereo 4-way or mono 8-way split is required from the same source(s). When expanding to one more FPS 28, a 1/4" to 1/4" patch may be made. The expand input may also be used as a primary input. In the out position, the respective input stage is set for microphone input levels. In the depressed position, line level signals are accepted. These four 1/4" tip-ring-sleeve jacks provide all eight outputs of the FPS 28. Each contains a pair of signals, Bus A is on the tip and Bus B is on the ring. This switch provides the ability to separate chassis ground and signal ground. Normally, this switch should be in the LIFT position. In some circumstances it may be necessary to move it to the opposite position to eliminate stubborn hum and buzz problems. We realize a scientific explanation of this switch would be helpful, unfortunately science doesn't seem to have much to do with it. [. . . ] The unit is shipped with this switch in the "grounded" position, tying circuit ground to chassis ground. If after hooking up your system it exhibits excessive hum or buzzing, there is an incompatibility in the grounding configuration between units somewhere. Your mission, should you accept it, is to discover how your particular system wants to be grounded. Try combinations of lifting grounds on units that are supplied with ground lift switches or links. [. . . ]