Hello, in another thread I have already asked for connection options for a subwoofer with double swing coil and have come to a good result there. I would like to use a subwoofer in my car with closed trunk. The housing should be closed and I would like to build it myself. I have a lot of experience in woodworks, but I do not have the expertise in loudspeaker electronics. It should be a 12 inch LS, so a 30 cm ch Assis. At the moment I prefer 3 chassis: – JL Audio 12W3v2-D4 – Hertz Energy ES300 (or the current version ES300.5) – AudioSystem HX12SQ I downloaded the program WinISD in the free version for the calculation of the case… but that doesn’t make me really good. I think that a case of about 30 liters should be good for this 3 chassis. Now I just have to find one way to calculate the exact dimensions.Example: If I use a chassis for example. The case has a volume of about 39 litres from 45 x 35 x 25 cm (W, H, T). But then the chassis has to be deducted from the number of liters… but with how many liters each? I assume that this can be determined via the Thiele Small parameters. And what if I want to contain something in addition… how do I calculate that? Probably this can be done automatically with the Pro version of WinISD. But I don’t have that.Example 2: If for example for a Hertz ES300 (old type) a housing of about 20 liters is described as optimal, I have to have a possibility to determine the dimensions for the housing itself if I want to build it myself. I assume that with this liter-rate of 20 liters the chassis is NOT included (i.e. 20 liters net). Therefore I need your help for the calculation, but also gladly for the selection of the suitable chassis 😉 Greeting Yank