3Com CP-1 owner manual Theory and Design

Theory and Design

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Panorama can be used with music, films, or from within the Reverb and Ambience programs to simulate side speakers if the listener is inside the effective area between loudspeakers.

When the front speakers are close together, the Panorama Effect is less precise but more dramatic, and it works over a larger area.

In a well-damped room with loudspeakers mounted on stands away from the walls, the Panorama effect can be very exciting, giving the closest possible approximation to the actual hall used for the recording. With true binaural recordings (made with a modern dummy head with accurate external ears and proper equalization) the playback can be uncannily realistic. And, unlike previous versions of this technique, the Panorama program adds virtually no coloration to the original signal.

Panorama is used in two ways in the CP-1. First, there are the three Panorama programs, designed to reproduce as closely as possible the sound actually recorded by the engineer. If the recording has good natural ambience, Panorama will spread that ambience around the listener, giving a true impression of the original hall.

The Normal and Wide versions of the Panorama program differ primarily in their handling of low-frequency signals. Normal is designed for record- ings whose bass energy is evenly distributed across the stereo stage; Wide is designed for recordings with centered bass. The only other difference between these two programs is in their initial Effect Level. If you need more bass from Panorama Normal, use Wide and reduce the Effect Level. Conversely, if Panorama Wide is too bass-heavy, use Normal and increase the Effect Level.

The Low Frequency Width control provides another important adjustment to the bass in Panorama. This control is a simple implementation of a Spatial Equalizer (a function which Alan Blumlein referred to as a “shuffler”). One of the ways ordinary stereo excites SI is through the out-of-phase low frequency energy in the recording. The Low Frequency Width control allows the amount of out-of-phase bass in a recording to be adjusted. Even when the Effect level of the Panorama control is all the way down, the Low Frequency Width control is active, allowing the user to experiment with this property of sound.

Recording engineers have only recently become aware of Spatial Equaliza- tion3,4 and many older recordings are greatly improved by increasing the low frequency width a little. When the rest of the Panorama program is not used (by turning down the Effect control) just turning LF Width up a bit can make ordinary recordings quite spacious. The user should exercise caution, however, since some recordings (such as those on Telarc) use microphone techniques which already contain sufficient out-of-phase low frequency energy.

The crosstalk cancellation in Panorama increases the low frequency width as well as the high frequency width of a recording. Recordings in which the engineer deliberately added large amounts of low frequency width will sound too wide and phasey when played with either Panorama Normal or Panorama Wide. Negative values of the Low Frequency Width parameter can bring the low frequencies back in line with the higher frequencies and make the playback with Panorama more effective. The Binaural setting of

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