I will be starting my sonosubs next week. I am planning to make two subs, each using the Shiva driver mounted in a downfiring position and 16" sonotube. I saw a post on another thread from Patrick Sun that suggested a couple of possible designs for this driver(using LspCAD). The one I am currently planning on using is: 6ft^3 internal box volume 2 x 4" ports 23" long Tune = 17Hz 1) I will be using these subs mainly for movies. My room is approx 19x13x9. I usually listen at about 5-10db below reference, so I do not need insane SPL output (althogh I'd stil like a lot), but I want them to go LOW and stay flat. Am I on the right track with this design? (I dont have a PC so I cant run my own sims) What are the predicted perfomance figures for this design? 2) If I use the dual port configuration, how should I space the ports, evenly spaced between the side walls and each port or should the ports be as close to the centre of the enclosure as possible. I think I read somewhere that the port diameter should be at least equal to the distance between the port and the sidewall. 3) Has anyone measured the internal vloume displacement of the Shiva driver? 4) I've been doing some research on the net and have noticed that there are two sets of specs going around for the shiva driver. eg. the Adire site lists the Qts as 0.39, vas 150lt x-max 15.1mm, I found this specsheet reproduced on some DIY sites sites but some of the values were different (Qts0.38, vas 144l and xmax 15.9mm). At first I thought these would apply to the mk1 and mk2 Shivas but the xmax values are 15.1 and 15.9, the Adire site claims the Xmax was increased by 1mm for the mk2 driver. Whats the go here? I live in oz so I might not be able to get the mk2 over here, If the specs are different for the two how will that affect the cabinet volume and port calculations? 5) I will be installing an SVS style base plate ont he subs, how much space should I leave between the driver and baseplate? 6) I am currently using two Yamaha YST SW300 subs. Would it be possible to use the intenal amps from the Yamahas to power the sonosubs until I buy a deicated amp? The manual rates the amps as: 185w/5ohms. How should the Shiva VCs be wired? 7) What specs should I look for in an amp to power this combo? Amp suggestions welcome. Thanks in advance for all replies. p.s. I was initially planning to go the SVS route but because of the way the Aussie$ is looking and the freight costs to oz, TomV at SVS suggested I started looking at DIY. I was blown away by the price of this project. Total materials cost for the TWO subs is only $600aus.+amplification. To put that into perspective my YST-SW300 Yamahas cost me $1800 for the pair($2400retail). Harry ------------------ "You're too old fat man, and your tits are too big, get the f**k off my porch!"