Funny noises coming from my old sub, the venerable Velodyne V-1012-b, a unit that got good reviews in its time, has its own amp, is a sealed design with a 10" driver and a 12" passive radiator. This was a pretty high-end, made in the USA design in its day and people have kept them going for many years now.. The radiator was making rude noises and when I removed it, I found it had split open. No problem as it I bought it long ago and the rubber probably just got old. The Dayton Audio SD315-PR 12 is quite inexpensive and its construction is basically a light stamped frame with a stiff, modern-material cone and what seems to be quality, pliable surround that allows it to move fairly easily. After all, what moves a passive radiator is just the sound waves from the other speaker. It has to move reasonably easy or it wouldn't do anything. I had to modify the mounting area in order to properly attach and seal this radiator. You can never expect a universal speaker of any sort to ever just screw right in as most mass-produced speaker systems use proprietary components that are designed to pop in with a minimum of labor.The Dayton has a provision to attach washers as weights in order to increase the inertia of the cone and thus modify the response. I just left it stock and light for the quickest response. In the end, the operation was a success. I tried a variety of music featuring bass and it all worked, and in fact I turned the response to right where I had it originally, so the bass response is very much the same as the original unit. That is a good thing. In any case, the Dayton worked, was very reasonable in cost and would be a good choice as a universal replacement or if you are building your own sub.

I have yet to progress to the level of savy audiophile neardness where I can make my own speakers, so I cant say how thay stand up to that, but as replasment passive radiators thay are fantactic.For fifty bucks I got a pare of old-scool (40" tall with duel 12's) floorstanding speakers that had their passive radiators missing, leaving a 12" port in both of them.Puting these drone cones in the speakers tightened up everything in the sound, thay sound persice rather than hollow.Thank you Dayton!