Using the Auxiliary Sends and Returns

−∞ +10 AUX 1

−∞ +10 AUX 2

−∞ +10 AUX 3

	0
−∞	+20	L	R
RETURN 1 LEVEL			BALANCE

	0
−∞	+20	L	R
RETURN 2 LEVEL			BALANCE

	0
−∞	+20	L	R
RETURN 3 LEVEL			BALANCE

The MPL 1640’s system of Auxiliary sends allow you to combine the signal from multiple channels and send the resulting mix to external devices such as effects processors. When an Aux send knob is at the “0” position, the signal is routed with unity gain (that is, no boost or attenuation). As it is turned clockwise from the 0 position, the signal is boosted; as it is turned counterclockwise from the 0 position, it is attenuated. Auxiliary send 1 is always pre-fader; that is, the level of the signal sent through this knob is determined solely by the input trim and is unaffected by the channel fader position or EQ settings; for this reason, it is opti- mum for applications like headphone cueing or sending a feed to onstage moni- tors—both situations where you want the performer’s mix to be independent of the main mix. You can also use Aux 1 to route signal to a reverb processor in order to create a distancing kind of effect where the “wet” reverb signal remains constant even as the “dry” source signal fades away. Aux sends 2 and 3 are post-fader; that is, the level of the signal is determined by the input trim, the EQ settings, and the position of the channel fader. Here, raising or lowering the input level of the channel will affect the send level as well.

The MPL 1640 also provides three stereo Auxiliary returns. These allow you to return signal from outboard devices, either in stereo pairs or monophonically (many popular effects processors provide a single mono input but have a pair of stereo outputs). In practice, you’ll probably want to use the Auxiliary returns to bring in signal from connected effects processors. If the effects processors have stereo outputs, they should be connected to both the left and right Auxiliary return inputs so that their stereo integrity is retained. If they have mono outputs, you can route them to either the left or right inputs and then use the Auxiliary return Balance control to adjust the relative level of each paired signal. In this way, you can actually connect up to six monophonic devices to the MPL 1640’s Aux return section. Note that, when only the left input of an Aux return is con- nected, its Balance knob functions as a constant level Pan control, allowing you to continuously place the incoming signal anywhere in the left-right stereo field.

Note that the MPL 1640 Aux returns are hardwired to the Main Mix outputs; there is no provision for routing their signal to the Bus 3/4 outputs.