Room Correction Software question

[lovinthehd]

Because the delays aren't correct. Perhaps we should clarify... Are you saying that the distances in your 4700 match up to the distances you had in your 4520 x 0.889? That's the question. If your 4700 is already making the correction, then it doesn't matter if you use the editor app or the in-AVR version.

The 4520 switch to 4700 yielded same delays if you applied the math for the corrected formula for the 4700's "distances". Same otherwise afaict. I think the delays are fine, just the conversion to a "distance" seems to be the problem, which is easily ignored. OTOH if you changed the delays proportionately, what would the difference actually be?

 

[ReverendSlim]

The 4520 switch to 4700 yielded same delays if you applied the math for the corrected formula for the 4700's "distances". Same otherwise afaict. I think the delays are fine, just the conversion to a "distance" seems to be the problem, which is easily ignored. OTOH if you changed the delays proportionately, what would the difference actually be?

It isn't proportional though, it's differential. The closer speakers will inherently get more of a delay error without the correction.

I do feel like we're getting into the technical weeds on something I was merely recommending the OP try, since it's a known issue.

 

[lovinthehd]

It isn't proportional though, it's differential. The closer speakers will inherently get more of a delay error without the correction.

I do feel like we're getting into the technical weeds on something I was merely recommending the OP try, since it's a known issue.

Differential how? I am not grasping why closer speakers get more of the "error"....

 

[isolar8001]

I don't know....after hearing all this, I'm just going to throw my setup down the cellar steps and get a Bose Wave.

 

[ReverendSlim]

Differential how? I am not grasping why closer speakers get more of the "error"....

The quick and dirty explanation: Say you have speakers at these distances - 12 feet L/R, 10 feet C, 6 feet surrounds. The delay applied is based upon the speakers at the greatest distance so that they're constructively equidistant. It delays the closer speakers so that they arrive at the same travel time as the speakers at 12 feet of distance.

So let's look at the delay being applied with the D&M speed of sound error, where 1ft = 1ms of delay. With these measurements plugged in, the center would get 2ms of delay and the surrounds 6ms of delay.

Now consider that the accepted value for speed of sound (at 74F) is actually 1.132ft = 1ms. So the amount of delay that SHOULD be applied would actually be 1.778ms for the center and 5.334 for the surrounds. You can see that because the center is closer to the mains (the most distant speaker), you're only off by a small amount, which would likely not be noticeable in practice due to the precision we're working with on the AVR (0.1ft increments). But because the error builds with each foot, the surrounds are off by a more significant amount. Where you'd hear that would be in sidewall imaging between the mains and surrounds at the MLP.

(If I didn't explain it well or my math is a little off, just know that it's late and I'm fighting a kidney stone right now, so... I hope this makes sense.)