A Question About Time Alignment

Hi Paul,

    I have a time / phase aligned, and room corrected system at the listening position by way of digital crossovers processed through my Mini DSP using a mic that has a 30Hz-30KHz sensitivity range. Let me first speak to the basic principle of time alignment. You are correct, all frequencies being played travel at different speeds to your ears. Assume that the microphone is your ears. It has captured that moment in time of the recording when all those different frequencies met. You want to reproduce that at the listening position so that you hear what the microphone heard. If you time align the speakers, all the frequencies hit your ears at the same moment in time so you then hear the same “time distortion” that the microphone picked up. You are hearing what you would have experienced live. If the system isn’t time aligned you are compounding distortion by the variation in wavelength speeds. The highest sound we can hear is a sine wave about an inch long and the deepest sound we can hear is a wave 25ft long, they travel at very different speed so the higher sounds need to be delayed and the lowest played first. If one wants to truly create a “realistic” experience the system needs to be time aligned. This is not quackery as some have suggested but one of many important pieces of the puzzle in music reproduction. The speakers and their interaction with the room combined with their time / phase alignment are the factors with the most impact on creating a 3-D Holographic image “like being there.” I think physically aligning the system by ear would be next to impossible and the manufacturer can’t do it unless they tell you exactly the distance you would need to sit for them to be aligned as will as how far apart the speakers should be placed. I can turn off time alignment and room correction with a click of the button. Without time alignment the system is flat, with it I would put my listening experience against the most expensive system you can find. I hope this explanation helps. 

Thanks,

Steve

You are correct, all frequencies being played travel at different speeds to your ears

BS

they travel at very different speed so the higher sounds need to be delayed and the lowest played first

BS

This is like high school science stuff.

If it it did work like you say, then the lightening bolt would a crack and woofer notes arriving later. But roll of thunder is more likely stuff we cannot see happening above the clouds.

Please don’t be rude and call science BS because you don’t believe in it. These are measurable results that I can produce which you can hear and isn’t BS in any way.  Your example with thunder and lightening is a great practical high school example. Thunder is caused by the lightening strike by expanding air around the bolt. Light travels at the speed of 186,291 miles per second and sound travels at 1,088 feet per second (depending on the air temp) so if you count the number of seconds from when you see the lightening bolt to the sound you hear and divide by 5 that is roughly how many miles the strike is from you. If there is no time between the strike and the sound find cover! Science my save your life in a thunderstorm and it can help reproduce the best recording reproduction you will ever hear. I learned a lot from this site and feel it is important to respect all views on the forum. If you have measurable scientific data that I’m full of BS I’d love to research it but I’m afraid the entire study of Physics and my ears disagree with you. 
 

Thanks,

Steve

@hifidream Steve, your post was great except for the velocity being a function of the frequency.

I can see how one might think that the velocity is a function of frquency as t links like this show v = freg * wavelength

let’s just round off the speed to 1 foot/millisecond.
And at a 1000 feet away the 1Hz takes a second to travel it.
what amount of time does 20Hz take to arrive?
And what amount of time does 20kHz take to arrive?

I have no doubt you MiniDSP sound good, and I suspect that the tweeter to woofer delays are on the order or inches or fractions of a millisecond.

if the speed was a function of frequency the the lightening crack would sound like a descending chirp from 20KHz down to 20Hz.
But it doesn’t, we see the lightening and we hear the crack a bit later. When it is so close that it is almost simultaneous our we also tend to crap our britches.