OK I came across something strange I hope you have some insight on...
I tried adjusting the sub distance (+ and -), the sub phase, and even the mains distance (+ and -) in all sorts of combinations. Nothing took out the peak at 80 so I put all those settings back to how I had them originally.
HOWEVER then I discovered something quite odd...
Basically I was giving up and just planning on living with the peak at 80. After I did my final measurement I did some listening and decided the sub was outputting at a bit lower volume than I prefer.
So I used the volume level on the sub to increase things some - I guess it was about 5db. Then before finishing for the night I decided to remeasure.
I was quite surprised to see the peak at 80 was just about gone! Also my curve was slightly different and improved in some ways. I now had a couple db dip at about 22hz and 60hz which I fixed with a +2 gain filter (I know, I know but i can't help it!
)
Bottom line is that my curve now looks near perfect. HOWEVER I am quite confused... why would I get one curve and slope at one db level of the sub, and something different at high or lower levels?
So anyway after I was done I took a few more measurements and found that with my overall system level db changing (i.e. very loud vs. loud vs. average level etc) I would get different response curves from REW.
So I'm left wondering - what is my real response curve? Is my system now properly eq'ed only for a particular listening level? Thanks!