Members InACanProductions Posted June 2, 2005 Members Share Posted June 2, 2005 How many milliseconds of delay do you use per foot of distance when aligning say your FOH to the backline? For an example lets say the stage is 16' deep, and the amps and drum set are side by side 12' from the front of the stage. The FOH speakers are to the sides of the stage which is 24' wide. I'm just looking for a general thing here, and really I'd like to know per foot how many milliseconds delay to use. I'm not big into time aligning things. I don't have a laptop with SMARRT or a Driverack so the most delaying I can do is with my digital EQ and align to the backline. I'm open to trying something new especially something like delaying the to the backline since that would only add a few seconds to my set up time. Any thoughts are appreciated. Thanks. Link to comment Share on other sites More sharing options...
Members Ear Abuser Posted June 2, 2005 Members Share Posted June 2, 2005 the speed of sound is roughly 1100 ft/second (depends on temperature and elevation) so 17 feet/1100 = 0..015 sec. or 15 millisec. google speed of sound and you can get the correction factors for your temp and elevation. Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 2, 2005 Members Share Posted June 2, 2005 Notice that there will be a delay error of about +2.5mSec if you measure from the center area in front of the stage. The only place where the delay applies is the vector radius passing from the drums (backline datum) through the speaker stack and on to infinity. Everywhere else will NOT be time aligned. A compromise would be to choose an average delay of 13.5 mSec that will result in minimum aggregate error throughout the measurement domain, though technically not textbook correct for those with a Smaart hard-on. Frankly, I have not heard enough of a difference over the average listening area (on a smaller stage) to justify the effort. On a large stage, with a large flown system, there can be some benefit in reducing the AVERAGE delay difference but we are talking about stages with widths of 75+ feet and depths of 40+ feet. Of course, with tiered stadium seating you have a third dimension to consider when calculating the average delay as distance does not vary as much for a flown system which tends to track the change in elevation more evenly naturally. Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 2, 2005 Share Posted June 2, 2005 Originally posted by Ear Abuser the speed of sound is roughly 1100 ft/second (depends on temperature and elevation) so 17 feet/1100 = 0..015 sec. or 15 millisec.google speed of sound and you can get the correction factors for your temp and elevation. Actually, I believe the concern is more-so with barametric pressure rather than elevation. I think humidity is probably a somewhat significant factor too. I'll go look at the google calculator. Is there a specific website with the calculator? Link to comment Share on other sites More sharing options...
Members Steve_B Posted June 2, 2005 Members Share Posted June 2, 2005 This question gets asked a lot. Here Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 2, 2005 Members Share Posted June 2, 2005 Steve's explaination parallels mine exactly. For the time-alighment is a must guys, the math just doesn't support your argument and the difference is not a clear improvement at all. Link to comment Share on other sites More sharing options...
Members Ear Abuser Posted June 2, 2005 Members Share Posted June 2, 2005 Is there a specific website with the calculator? http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html this will give you the temperature effect -Elevation gets more complicated- Elevation affects the density and humidity and if you go high enough, the temperature- they can all be factored in but I think temperature is the primary factor. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted June 2, 2005 Members Share Posted June 2, 2005 And then there's the BAC factor. Are people really going to be sober enough to notice (or even care)? -Dan. Link to comment Share on other sites More sharing options...
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