I have always known that in my particular setup my room was boosting ~40 , and today I found out that I can overload the room mode
The CM140 meter I ordered from Parts Express arrived today, the specs for my first run are as follows:
Yamaha 663 LFE@ -1, vol level for 85dB cal= -20 sweeps in 2ch Stereo with mains set as small x-over @ 160Hz
Output level for this run @ 9 o'clock
And so now I can produce actual SPL calibrated graphs like so:
From the bottom up the volume was increased from -20, -15, -10, -5, -4, -3, -2, -1, -0dB. As you can see, I've got a monster room mode. I'm not so bothered by the response now that I see what is going on. So in the end it looks like this won't be so lean in other builders setups as it is in mine. The new larger cabinet design should be just about perfect.