Monitor Controller Owners Manual

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RESPONSE  The response controls the ballistics of the SPL meter. Available options are slow and fast. The
default is fast.
12 ABOUT CROSS-FEED
When listening to loudspeakers in a room, your left ear hears sound primarily from the left speaker (and
vice versa) but also receives a signal from the right speaker at a lower level and with some time delay
compared to the right ear. As well, the right speaker sound that reaches the left ear does not have a at
frequency response as the sound waves have traveled around the shape of your head before reaching
your left ear. The brain uses delay, level and frequency response characteristics to process the location
of a sound and hence, create an aural image.
When listening through headphones, each ear only hears the sound from one transducer and the
mixing of signals between the ears does not exist. In this situation the brain is left without many of the
psycho acoustic clues required to generate a properly distributed image and an accurate sound stage.
The result is that instruments seem to cluster in the far left, far right or center of your head. Since the
vital clues are absent, the brain has a dicult time deciding how to process the sounds coming from the
headphone, which can result in listening fatigue when listening for extended periods of time. The m905
contains circuitry which electronically simulates the signal cross-feed that occurs in a real acoustic space
and helps the brain establish instrument locations across the entire sound stage. While it is dicult to
perfectly model the very complex level, delay and frequency response characteristics of the head, the
cross-feed circuitry in the m905 gives the brain some of the basic clues it needs and the result is a very
pleasing simulation of an acoustic space. We chose the parameters of the cross-feed circuit to nd a
good compromise between accurate imaging and tonal neutrality. For recreational listening there
could be more aggressive modeling of the head related transfer function (HRTF) but this is usually at the
expense of adding tone color. For critical monitoring during the recording/editing/mixing process the
user will nd that the m905 cross-feed circuit provides a sonically neutral character.
Below is a frequency response plot showing the response of the m905 cross-feed circuit. In this graph
one channel of the headphone amplier is driven. The two traces show the direct channel and the op-
posite (cross-feed) channel.