He said the first graph was plotted with Audyssey off so no DEQ either. Audyssey cannot flatten his bass response so naturally we see some minor peaks and dips regardless. DEQ would simply apply boost to the low frequencies in such way that, as Dr. Kyriakakis said:
"Dynamic EQ should be left on. It will preserve the octave-to-octave balance of the content as you turn down the volume to make up for the changes that happen in human hearing at lower listening levels."
It is like the old "loudness" feature except it is dynamic, so it varies with the frequency, as frequency increases, it boosts less. That's why even if, say the 20-100 Hz graph is perfectly flat with Audyssey on and DEQ off, when you turn DEQ on, it will boost the lower frequencies but apply less boost as frequency increases, hence the "roll off" like look. The effect of DEQ and the resulting appearance of "roll off" will be more severe at spl much lower than reference level; and will level off as it approaches reference. At reference level, the graphs with DEQ on and off should look the same.
I would like to link the example graphs that used to be on the Audyssey site but all those pages are gone. I don't know why Audyssey appears to have abandoned Audyssey to some degree, maybe they are working on something new and don't want to support their aged XT32 SubEQHT product to the same degree they used any more.
