Right. I have one Talon Roc, two sealed 10" and two ported 10". Main speakers are Talon Khorus. In the beginning with just the one Talon Roc I tried many different locations none of them working until I finally gave up and lived with the least bad location. Didn't know at the time this is what always happens every time no exceptions when using only one sub.
Then when I built the 4 DBA subs I just put one near the wall different distances from each corner and immediately without any effort at all had bass that was better than I ever heard anywhere ever before.
This bass by the way, without any attempt at integration was not only seamlessly integrated but tight and fast and articulate and powerful and smooth and extended. The bass in other words was darn near perfect and all I needed to do was adjust the levels. My Dayton amps allow both level and EQ and phase adjustments. Rather limited EQ, it really only allows one peak or trough to be tweaked, but with DBA that is more than enough. Phase theoretically must make a difference, although in practice I have never been able to hear it. Duke and Tim seem to, so maybe this is one of those things where there is a difference its just hard to notice until you learn to recognize it. Not having ever heard bass like this before maybe I will in time. What this does however is put it in perspective. The bass is so good most people, even really diligent picky listeners like me, will consider it more than good enough.
Now having read Geddes as part of my due diligence before building my DBA it seemed adding a 5th sub would bring marginally less improvement. Instead it was a pretty significant improvement. Just my opinion, but I don't think this has much if anything to do with optimal placement. When the Roc went back in it did not go where it was, it just went where I had room. Even so, as I said before, suddenly with that 5th sub I was feeling crazy low bass, much lower than I ever heard from the Roc back when it was used solo.
In hindsight there's actually a pretty good reason why this would be the case. The Fletcher-Munson curves are a graphic representation of how we perceive sound levels at different frequencies. What they show is when it comes to very low frequencies, below a certain level we just don't hear them at all until they get loud enough. But then when they do get loud enough to cross that threshold all of a sudden we hear them really well. This makes bass especially hard to do. Because until the bass gets loud enough to hear you can change the level 2, 3, 4 or more dB and hardly make a difference. But then suddenly when it reaches the threshold even a 1 dB change matters.
So in a way Geddes is right. Adding that one sub probably only improved things a very small amount. But that amount was enough to get me to the threshold where it is perceived as being a lot.
This is a good example of one of the many ways really low bass is so very different from, and requires different approaches than, the higher frequencies from the mid-bass on up.
