Originally Posted by voyagerx
Just wanted to give an update on some of my tuning and experimenting. Although my system has been sounding ok, there was some noise in it and a few songs that just didn't sound right to me - some vocals and instruments sounded hollow (can't think of a better way to describe). Using a microphone I have measured the response of the system, and have a huge dip in response around 2.59kHz and a smaller dip in the surrounding frequencies. Looking at the photo above, you can see this same dip. The 3Sixty.3 during its auto-normalization had boosted each of the channels at 2.5kHz with around 15db. This didn't seem to actually add back any of the missing frequency, but did add the noise.
I found this weird that the 3Sixty needed to do this, because there was no obvious dip at 2.6kHz in the initial channels I measured, much less a 15db dip.
I wrote Rockford and confirmed the 3Sixty.3 does not do any time alignment on any of the channels before summing. (The JBL MS-8 is the only one I know that advertises that it corrects time alignment before summing, and then allows time alignment on channels after summing). The factory must have a time delay of around .38 ms more on the tweeter than the woofer and summing these two signals causes phase cancellation around 2.6kHz that also effects the surrounding frequencies. Even with 40db of EQ, you can't add back frequency that isn't there.
So.... ultimately I ended up separating the channels and EQing each one independently since I am running my components active anyways. Using the 3Sixty.3 auto normalize on each of the channels independently has actually created a much flatter frequency response and I no longer hear the vocal issues I was hearing before. I have also eliminated the hiss I was getting from the 15db boot the 3Sixty.3 was trying to add to fix the issue.