Distance Formula

[Jim-surround]

Again, I could use a little guidance. Because of the shape of my listening/viewing room, the left surround is 3 feet farther away from the center of the listening area than the right surround. Both are 6 feet off the ground and slightly behind where we sit. Is there a general formula or rule to determine the amount of delay for the right surround so the sound from both gets to the listening area at the same time? Or, is the difference so small that it doesn't matter. I'd rather not sit around for hours messing with delay values if I can figure it out some other way.

I'm wiring up the surrounds now, so by the time I'm done maybe someone will have some advice to share.

Thanks in advance.

[Burke Strickland]

When you say "center of the listening area" are you referring to the center-most seating position or the geographic center of the room? Speaker distance or delay settings should be chosen for the effect from where people actually sit, not the center of the room, unless that happens to be where someone is most often postioned when you play a movie.

Some receivers and pre/pros have independent "distance" settings for each surround speaker, which automatically sets the delay. If those settings are available, that would be the way to go. Simply measure the distance from the most-used listening position to each speaker and enter thiose numbers at the appropriate place in the setup menus.

One other factor to consider is that when more than one person is seated in the room, then unless everyone is on someone elses' lap, only one person will ever be in the spot for which the settings were assigned anyway. Someone will be closer to the right surround than the left surround and vive versa. In most systems, there is no practical way to optimize all speakers for all seating postions.

So if it sounds good the way you have it set up now, I wouldn't worry about it. And I certainly wouldn't spend "hours messing with delay values" -- spend that time enjoying a few movies instead!

Good luck,

Burke

[whoaru99]

I think a general rule of thumb is figure 1 ms delay for each foot from the speaker to the desired listening spot.

[saurabh]

thats correct....

thats correct 1.1 ft = 1 ms delay to be precise

The speed of sound in air is: 1100 ft/sec

1100 (ft/sec)*1(sec/10^3ms) = 1.1 ft

Every 1 ms of delay added corresponds to 1.1 ft of increased distance of your speakers relative to your listening position.

[Jim-surround]

By "center of the listening area" I did mean the center-most seating position. Sorry I wasn't a little clearer on that. That's the spot I work around. I guess my wife will have to sit on my lap to hear the best sound and see the best picture

The delay time per foot is great. I really appreciate it. I'm a little embarrassed because many moons ago I took a number of physics classes when I went to college. I guess I should be glad I can even remember that I went to college.

Thanks to all for the help.