In PD, and since my sub is close to my mains, I set the sub to roll off at roughly 1.25-1.5 times my main speakers lowest stated measurement via the sub amp's DSP. Then I turn the sub's gain down accordingly by ear to account for room gain, which is a lot in my case. This is also why I chose a smaller, 12" subwoofer driver in a sealed enclosure. My main speakers also have 12" woofers and this goes completely against current prescriptions for a correct match but it manages to be more than enough of the 'right kind' of bass for my room.
A friend of mine brought over a ported, 15" sub before I built mine and by his preference, it sounded 'blappy' to my ear and I could barely distinguish lower bass guitar notes from rumble effects in theater use and yet he loved it rather obnoxious like that. That is what initially turned me off to the notion of using a subwoofer and sticking to being a die-hard, 3-way speaker only type of 2 channel listener. I have a set of JBL 3-way speakers with 12" woofers and the bass is some of the best I have heard in this room. To the point (on some music such as classic, or hard rock) where I don't care about the modern notions of 3 way speakers not being AC ( Audiophilically Correct). Some key hints being, something like the familiar and rather tasteful bass line in Elton John's, "Rocket Man," as an example.
We often hear the best idea is to relieve the main speakers of bass duty and send the lower frequencies to the subwoofer, which often times, is a single driver. At 80hz and above in some cases, and now we have a single driver handling more than just sub bass and up into the mid-bass frequencies and this seems a rather erroneous trade off to me. It seems if there is both mid-bass and sub-bass happening at the same time, we're kind of inflicting the same type of condition on another driver that we are trying to relieve from the mains, albeit different frequencies. I know this is wrong because the audiophiles tell me so and why but, I have heard so many systems with music with great low end, that manages to wash out the mid bass, at least to some extent, and it's usually that from the bass guitar or some of that mid-bass ambience. It makes me wonder how many dimensions of the overall soundstage are these measurements actually taking into account.
Finally, I know I am wrong about this and when I read why I am wrong, I understand why, technically. But when someone plays back music I am ultimately familiar with that they have calibrated with auto EQ and I am missing key bits and they just dismiss it as some artifact of my unwashed listening habits (which has included a lot of live music), I have to question their experience. Not with the equipment, so much as the music itself.
