I really want to build a 4x15 (or comparable) cab, and am quite intrigued by Mark Percy's design. However, I'm a little confused by the naysayers. From what I read on his website and based on my own acoustic knowledge, it would seen to be a pretty good design, but that also doesn't seem to be the case according to the pros. billfitzmaurice, fEARFUL, and a few others, I read some other posts of yours in a thread about someone building an 8x15 cab and others about the larger cabs, and while many of them definitely seem quite ridiculous, I'm just interested in getting some info on why pairing bigger speakers together seems to continually be considered as a design flaw in most of these threads. I like the smaller 10" cabs just fine, I currently own a few, they have a nice, punchy, crisp sound. But something they all seen to seriously lack is bass presence, and especially in a rehearsal or performance situation without having to crank the bass on your amp and overwork your drivers. I used to own an 18" extension as well, and felt that it really added a lot to the overall presence of the sound, but it also made my sound difficult to tailor, and added another cab to load in/out and take up more space as well as more backbreaking trips to the truck. I kind of thought that doing a "best of both worlds" build with slightly bigger speakers with a deeper and presumably more present tone would slightly increase the weight of one cab, but vastly reduce the amount of cabs that I need to haul around, which is why I'd like pro expertise on this subject. Another of my little issues is that I play subcontra bass and want a cab that can seriously stand up against a sub C# (somewhere around 17Hz, I believe) at higher volumes without breaking the bank.