So I was running Digital Video Essentials audio tests, specifically the subwoofer phase check, which runs test tones at 30,40,50,60,70, & 80Hz for 10 seconds each. Here's where it gets strange....

At "0", the test tones meter within a couple db of each other at 30,40,60,70, & 80Hz. But at 50Hz there is almost a 10db drop-off in level(!!!).

It gets stranger...

At "180", the test tones meter within a couple db of each other at 30,40,50, & 60, but fall nearly 10db at 70 & 80Hz.

All this with no physical movement of the subwoofer, and I have a very symmetrical room. I did have ARO engaged and the E.L.F. control set to -12db (I know I have a massive peak at 25Hz).

Any theories or anyone else with a similar finding?

I am going to test tonight with ELF at 0 and ARO defeated.

So I was running Digital Video Essentials audio tests, specifically the subwoofer phase check, which runs test tones at 30,40,50,60,70, & 80Hz for 10 seconds each. Here's where it gets strange....

At "0", the test tones meter within a couple db of each other at 30,40,60,70, & 80Hz. But at 50Hz there is almost a 10db drop-off in level(!!!).

It gets stranger...

At "180", the test tones meter within a couple db of each other at 30,40,50, & 60, but fall nearly 10db at 70 & 80Hz.

All this with no physical movement of the subwoofer, and I have a very symmetrical room. I did have ARO engaged and the E.L.F. control set to -12db (I know I have a massive peak at 25Hz).

Any theories or anyone else with a similar finding?

I am going to test tonight with ELF at 0 and ARO defeated.
Scott,

Nothing "strange" here at all. You're simply experiencing the effects of a small room on bass frequencies. The wavelengths of bass frequencies are so long that, when the reflections of the waves off the walls combine in the room, sometimes they "add" to each other, (when they combine in-phase), and sometimes they "subtract" from each other, (when they combine out-of-phase.) This is what gives you the "peaks" and "nulls" in your room. Changing the phase changes the "time" of the wave, (it inverts the polarity so that the positive of the wave now becomes the negative, and vice-versa. The reflected waves now interact differently with each other and change the peaks and nulls.

Try moving your SPL meter a few feet left/right and front/back. You'll find a whole new set of peaks and nulls. Fun, ain't it?

BTW, having a symmetrical room is one of the worst situations for bass peaks and nulls, especially if the dimensions are all similar or multiples of each other.

Also, the problem will likely get worse with ARO off. ARO looks for the largest "peak" and reduces it's level. Turning it off will add that peak back into the mix.

The E.L.F. trim is a worthless feature on the JL subs. It's actually just a broadband volume control. See the measurements of it's effect in the F113 thread, Post #4916 by xcjago:
http://www.avsforum.com/avs-vb/showthread.php?t=736243&page=164

Craig

welcome to the laws of physics, Mr. Bond...