ART Pro Audio TPatch - Eight Point Balanced Patch Bay - Manual (Page 8)

All connections start at the rear of the unit. By
convention, the top jacks are inputs and are connected
to audio sources or sends and the bottom jacks are
outputs and are connected to audio destinations or
receives (see left diagram above). With no connections
at the front of the unit, the vertical pair of rear panel
jacks are connected together internally. An audio signal
will flow from the top jack to the bottom jack without any
patch cords plugged in at the front in what is known as a
normalled connection, shown in case A in the Half
Normal and Normal diagrams above.
So far we've connected audio outputs to audio inputs,
which we could have done with just cables. But using
the jacks on the front of the unit is when things get
interesting. The convention on the front of a patch bay is
that the top jacks are outputs and the bottom jacks are
inputs (see right diagram above). This is just the
opposite of the rear connections, but makes sense if you
think of signals flowing through the patch bay.
With the rear panel pushbutton in the out position (Half
Norm), the Half Normal mode is selected (refer to the
Half Normal diagram above). This is the patch bay mode
most commonly used. In this mode we can plug a cable
into the top jack and take out or monitor the signal
flowing through the rear jacks by sending it to an
amplifier input or a set of headphones. This is shown in
case B. However, if we plug a cable into the bottom
jack, we break the connection between the rear jacks.
Thus we can put in or patch a signal that replaces the