Hey all! As I'm sure most of you are already aware, I am terrible for procrastination and take fooooreevveerrrr to actually make a decision on what I could do for a DIY sub. I do love my SVS PB12-Plus/2 but I'm aware it's not got that mid-range punch of others, does not dig that deep below tuning (16Hz with two ports plugged, although it is pretty floor shaking at times!) and does not have as much output as I would like at the low end. Inspired by everyone else's excellent builds I have been thinking about replacing the SVS with something a bit bonkers - do it once, do it right, and all that jazz I have therefore been playing with WinISD now I have (finally!!) got it to work on this knackered old laptop at home, and think I've worked out a box that might be ok? So, I would welcome your feedback on the following attachments!! I'm thinking 4xSI18s, a CV5000, 11 cu ft sealed... It 'feels' like it might be a bit small, with each driver only seeing 2.75 cu ft rather than the 6 cu ft needed for Qtc of 0.707, but the power would be there from the CV5000 and the graphs appear to show that XMax of c.22.5mm would only be reached at just about 4Hz, with XMech of 35mm / 43mm (Databass estimated measurements / SI ratings) reached at between 1.5 and 2Hz, which shouldn't be a problem because the amp starts roll off at 5Hz, I believe, and room gain should provide a half-decent boost (6-10dB on a good day??). I think the 8033 can boost down to 5Hz as well, so that could be an option? (I can't work out how to apply a boost in WinISD ) Anyway, any thoughts are much appreciated!