brucek on how to set up a simple house curve:
The last time I moved my equipment around I had to go through the routine of re-doing my BFD filters because the response of my sub changed significantly in it's new position.
I did such a swell job this time that it was ruler flat from about 16Hz to my crossover at 60Hz. While I was happy that I did such a nice job of taming my peaks and valleys resulting in such an enviably flat response - it sounded like, well, crap..........I could see Wayne P standing there asking me why I didn't add a house curve.
It was such a pain to get all those filters to create a flat response, I knew it would be even worse trying to get an even smooth house curve designed in. I was wishing the BFD had a shelf filter that I could hinge at about 30Hz and evenly drop my entire sub response by a predetermined amount while leaving my other filters intact.
Then I had an idea, that if I added a single filter up around 400Hz with a very wide bandwidth and a large cut, designed so that its final effect would reach down to about 30Hz, that I would have a smooth drop from 30Hz all the way to 400Hz. It would essentially tip or hinge the shelf at 30Hz and continue to drop increasingly, all the way to the filters center frequency.
This would be a pain to calculate so I decided to try the BFD design software to get a look on a graph what values would work. Well, I found it so easy to enter this single filter into the design software and make adjustments while watching its graph until I found a filter that would work. I then added all my other filters into the design software to see if the effect I was looking for worked. It worked very well. If I enter just my filters that create the flat response in my system they (not suprisingly) look like an exact mirror of the "no-filters" Excel file of my system. Then if I add my "house curve" filter along with my other filters, I get a very nice tilt starting around 30Hz and dropping smoothly from there. I could easily increase the tilt by altering the single "house curve" filters cut and I could easily change the frequency where it starts to take hinge effect by altering the single "house curve" filters center frequency. The filter that I am using that works well in my system is a 366Hz filter with a bandwidth of 120/60 and a cut of -15dB. The phasing problem that occurs at 366Hz from this filter is outside the range of my sub, so it can be ignored. I wouldn't have wanted to try and create the value for that filter without the design software, so that's why I recommend it..............
Now, of course, once this filter is applied, I had to add a small wholesale increase to my subs level control to compensate, but the change was not large and I could afford the small loss of headroom.
This allows me to have two programs, one with the "house curve" filter and one without, for a flat response. Or, I could have several programs with various single house curve filters for example, one for movies, one for music etc.....
Here's graph of how the filter should react: