The SW905 panel has ¼” phone jacks labeled ‘Record/Line Out’ and
‘Line Insert’ respectively. ‘Record/Line Out’ provides a feed from
the Mixer stage, but before this signal goes through the Output stage. In
other words, this signal is not affected by settings on the music/voice
switch, treble, bass & master volume controls. It can be used to drive an
external recording device or another audio system.
The advantage to this configuration (pre-EQ & master volume) is that the
external system’s own EQ & volume settings can be separately adjusted
to suit its environment and the two systems do not interact with each other.
The ‘Line Insert’ jack works in two ways. When no plug is inserted it
internally connects the Mixer to the Output. However, when a plug is inserted
it disconnects the Mixer from the Output, replacing it with the external
audio signal from the device the plug’s cable is attached to. In this
configuration, the SW905 Output stage can be used to amplify a feed from an
external mixer or playback device. For instance, assume a facility’s main
meeting room has a built-in sound system, but the adjoining room for the
overflow crowd has no system. A ‘Line Out’ feed from the house system
could be plugged into the ‘Line Insert’ jack of an SW905 located in the
overflow room. The SW905’s EQ & master volume can then be adjusted to
suit the overflow room’s conditions without any effect on the main system.
The other way this pair of jacks can be used is to insert an external device
such as a graphic equalizer, echo/reverb machine or other audio processing
device between the Mixer and Output stages of the SW905. The ‘Record/Line
Out’ on the ‘905 connects to the ‘Line In’ of the external device and
it’s ‘Line Out’ connects to the ‘905 ‘Line Insert’. Remember from
the above discussion that a plug in the ‘Line Insert’ jack breaks the
direct internal connection from the Mixer so in effect the external device is
electrically inserted between the 2 stages and becomes a functional block of
the SW905.
