Hi all, I had posted my attempts at BFD equalization of my SVS sub last year, fooling around with house curves and such. I decided I wanted to try things again with a flat response in mind with my sub and front mains which I hadn't tried before (previously had tried a flat response with sub alone). My "before" response this time and also last time had what I assumed was a null at 111 Hz and this is what Wayne A. Pflughaupt had also mentioned to me but I realized that I hadn't even tried to fix this dip because I assumed it was a null. I have looked at graphs of various other forum members here and other forums and noticed that some of them had an exact same dip at 111 Hz. I thought that maybe instead of it being a room null that maybe it was just the effect of the receiver's crossover and that the integration of the mains and subwoofer just wasn't working out as perfectly as the receiver wanted to. It is my understanding that there are numerous variables such as the frequency crossover point itself as well the different slopes of the high pass and low pass filters around this crossover point (which are different with different receivers) as well as the variable of the frequency response of the sub and mains themselves. Since these numerous variables are present, I assume the manufacturers of these receivers could not even hope to get a perfect ideal integration of the sub and mains at the crossover point with all the different combinations of sub and mains out there. Anyway, again since I noticed some other members' graphs having a similar dip at 111 Hz, maybe it was just an effect of the crossover by the receiver and not really a null. Even Wayne A. Pflughaupt had mentioned before that true nulls are usually of very narrow bandwidth (1/6 octave or less) and that dips present in the response may not be nulls but just what the frequency response happens to be or what I am suggesting, an effect from the crossover of the receiver. My Yamaha receiver has a fixed crossover at 90 Hz and I am using HTD Level 3 bookshelf speakers as my mains (and surrounds) along with an SVS PCI 20-39 sub. Here are my readings and settings on the BFD and the resulting before after response of the sub and front mains together: What do you all think? The so-called null at 111 Hz is gone so I assume it wasn't really a null or else I wouldn't be able to boost it. Isn't a true null resistant to all boosting? For watching movies, I am running the bass about 4-5 dB hotter than the mains (using AVIA test tones) and I think it sounds pretty good even though I had equalized for a flat response and I know there is a debate about how a house curve may be needed for things to sound right. I was wondering though, since I am boosting my bass the 4-5 dB, isn't that somewhat similar to the effect the way a house curve is made, ie. a rising response in the bass frequencies? I know it is not as exact as the frequency response that someone may be trying to obtain with a certain house curve (where exactly the response starts to ramp up and where it levels off, etc.) but is this logic wrong in aiming for a flat response and just increasing the level of the bass to get a good sound?