Originally Posted by spanish68
You can build a box of around 6cf which is only a little bigger than the PB13 sub. You want to use the 18-2100 PR's which will allow you to tune the AV15H sub lower, in the 16-17hz range, compared to the 15" PR's. The low end of the AV15H and PB13 subs should be very close (output wise), while the mid-bass range (40hz-80hz), the AV15H will have the advantage in output. How will the SQ compare to each other is hard to say, but I can tell you the AV drivers have great SQ. If you want more info of the sub and more help, go to Acoustic Elegance and simon5/John will answer all your questions and model the sub for you.
yeah, this is the closest design we've come to in this thread.
the thought flow seems to go like this: to go low, you have to tune the box low. to tune the box low, you have to have a larger box and/or bigger ports and to tune the ports low, they have to be super big or long, usually way too long to fit in the box. so instead of long ports, let's use passive radiators since those can be weighted down to tune to any frequency. and that's how we arrive at this design.
however, if you look at the SVS design, it pretty much contradicts every rationale used to arrive at the 2 PR design: it has smaller box; reasonable diameter ports that fit inside the box yet are tuned very low; and needs "only" 750W of amp power as well.
so it still raises the question of how the SVS design can work so well. if it is in the design of the driver, then what parameters are being optimized for this to work and do none of the other DIY drivers able to work like this? if it is the design of the box, then how come we can't design a DIY box like this?
sorry for over analyzing, but the engineer in me likes to understand things.