I have been reading a lot about house curve and Hard-knee curve. For those who are unfamiliar with hardknee curve, I'd recommend to read the link that braveheart provided. It's vary informative. One thing that article pointed out got me a bit confused.
First of all, since we are playing with the house curve and all these filters will be applied after avr has applied its filter, my understanding is that the whole process is done after full calibration of Audyssey. In other words, here is the steps I think we need to take to apply house curve
1 - Fully calibrate system. (8 point audyssey calibration process in my case)
2 - Switch to Auto mode in surround setting.
3 - Take measurement in REW.
4 - go to EQ section and set limit to 2-.130 and smoothing to 1/6
5 - Set target level that makes the target line crosses the graph reading around 30 hz ( I'm a bit confused about this part).
6 - Set Speaker type to subwoofer under Target Settings. Set low peak to 20 and high to 70 under Filter Tasks.
7 - Article asks to click on Optimize pk gain and Q. I don't know what that means and it shifts target graph and therefore I'm avoiding it.
8 - Click on Match response to target. This will create the graph that REW determined to be best to match Target graph.
9- Click on EQ Filters to see the filters
So this is what I understood after all the readings. Few points that confuse me are
The first step, naturally, is to determine how much of a slope your room needs. As I outlined in my house curve article, this is best established by playing pure sine wave tones at the crossover frequency and the point you want response to shelve, typically ~30 Hz. The idea is for the lower frequency (30 Hz) to sound as loud as the upper frequency (90 Hz, or whatever your crossover setting is).
Again is this after all the calibration is done? Since he is recommending to have on front and subs, I believe its best to keep surround mode to Sterio when finding the slope of room? One issue with this approach is that we are relying on our ears here. I mean the only way we can find out if 30hz is as loud as 90hz is by listening to it. Is there any other way to match it? Otherwise it'd always be like "was 90hz that loud???" question in my mind.
Second confusion is setting Target curve in REW EQ. My understanding is that the house curve graph (hard knee graph in our case that I input in house curve section) is the one we need to match. My graph stats at 86 hz but when I click on options defined in step 7, it pushes the target curve 10db above my graph. I don't understand what these options mean and how important they are?