Madrigal Imaging Audio/Video Preamplifier manual

Setting the Surround Delay

3REPEAT THIS PROCESS FOR EACH SPEAKER IN TURN

Pressing master will move the cursor (and the noise) on to the next speaker. When adjusting the subwoofer level, be sure to get up and walk all around the listening area, watching for the magnitude of the variations in- troduced by room modes at low frequencies. If more than 3-4 decibel variations are seen within the listening area, consider re-locating your subwoofers for more consistent results. (See Planning Your Installation for specific suggestions on subwoofer placement.)

4MAKE A NOTE OF THESE SETTINGS UNDER “YOUR SYSTEM SETTINGS” IN THE BACK OF THIS MANUAL

Having these settings handy will prove helpful should anyone ever tamper with your careful calibrations. Of course, you should re-calibrate the system whenever changing amplifiers and/or speakers, or when something has a noticeable effect on room acoustics (such as re-arranging the furnishings).

5PRESS ENTER TWICE TO SAVE YOUR CHANGES

Since these settings are critical to achieving optimal performance from your PAV, the on screen display will ask you whether you are sure you want to make these changes, and tell you to press menu to escape without saving those changes. Assuming that you do wish to save your changes, press enter a second time to confirm and save the changes.

All Dolby Pro Logic decoders incorporate a delay to the rear speakers. This delay takes advantage of the precedence effect, whereby we tend to localize on the first sound we hear when being confronted with several similar sounds (as in the case of surround sound, or a visit to a reverberant concert hall). The rear signal is delayed somewhat to ensure that we never hear any potential leakage of the front channels into the surround speakers, despite the fact that the latter are often closer to the seating area than are the main speakers. This delay gives the sound coming from the front speakers a chance to reach the viewer before the sur- rounds are heard. It can be varied from 15 to 30 milliseconds.

The best setting depends on the distance between the main seating area and the front speakers, and the distance between the main seating area and the surround speakers. (See below.)

1MEASURE THE DISTANCE IN FEET FROM THE FRONT SPEAKERS TO THE PRIMARY LISTENING POSITION

This number represents an approximate measure of the time it takes for the front speaker sound to reach the listener, in milliseconds. (Since the speed of sound at sea level is 1130 feet per second, sound travels approximately one foot per millisecond—close enough for this sort of work, anyway. Simi- larly, people using the metric system may use the approximate conversion of 3 feet = 1 meter.)

2SUBTRACT THE DISTANCE (IN FEET) FROM THE LISTENER TO THE REAR SPEAKERS

This difference represents the time “advantage” the rear speakers have over the front speakers, measured in milliseconds. Since they are usually closer to the listener than the front speakers, it is important for their signal to be delayed.