Elliptic Equalizer for 5.1 Surround Sound

DIMENSIONS
Surround Direction and Base Width Controller

In addition to the Base Width and the Direction Control, DIMENSIONS has an Elliptic Equalizer for Surround Sound that maintains compatibility and several EQ stages that are installed in the M/S signal chains of the module. These equalizer allow outstanding modifications of the spatial components of a surround signal.

The Elliptic Equalizer

The elliptic equalizer allows the user to modify the crosstalk in the lower frequency range of the signals. On the basis of the hearing physiology, direction detection is possible only with frequencies above 300Hz. Therefore it is not necessary to increase the width or depth of the program below the 300Hz frequency range. This feature enables transfer the low frequency range in mono, which maintains the spatial impression of the signal, and also helps to increase stereo compatibility.

The width elliptical EQ modifies the left/center/right low frequency crosstalk and the depth elliptical EQ modifies the low frequency crosstalk between the front and the rear channels. The width EEQ connects left, center and right and in parallel, left surround and right surround. The depth EEQ connects front left with surround left and front right with surround right. Additionally, the center is connected to both left and right surround and vice versa.

The control selects the frequency of a 15 dB crosstalk between the connected channels. The slope of that curve is 6 dB/octave. If the control is set to 200 Hz, the crosstalk is 15 dB at 200 Hz, 21 dB at 400 Hz and 27 dB at 800 Hz and so on. Below 200Hz the crosstalk is 9 dB at 100 Hz, about 4 dB at 50 Hz and about 1.5 dB at 25 Hz, (it reaches 0 dB about 6 octaves below the 15 dB frequency).

Particularly with application of base widening, the application of this procedure is recommendable. All base widening effects are based on the fact that the channels are connected counter-phase with each other.

The MS Equalizers

In both direction mixer sections there are two, selectable, fully parametric EQ bands. These equalizers do not regulate the signal in the normal format but in the MS level, which is produced by the regulation of width and depth controls. The equalizers only affect the mono signal interests in the width and/or the depth. The regulation in the side channel affects only the coherent, spatial signal interests. For the regulation of the width and depth, there is a Low-EQ for the center channel and a Hi-EQ for the side channels. This subdivision of the bands is located near, because the low frequency area of the signal is not place-cash. With these EQ bands gives the discount to itself and during the change of the space parameters the bass foundation of the program effectively adapt. The respective HI-EQ to is located on the contrary in the side channel and regulates the spatial interest of the signal. The frequency ranges covered by the two parametric bands are: 30Hz to 1kHz, and 1kHz to 20 kHz. The adjustable Q range is from 0.5 to 3 octaves, and the gain range is from -12 dB to +12 dB. Both equalizers can be selected independently.