>Some things are unclear for me:
>1. Should the big passive radiator be of the same size as the >speaker?

It should preferably be about 50% bigger.

>2. Did you build the passive radiators yourself?

I was with a big company and we had a suplier build them.

>3. How did you build the lever?

As below with a few mods - the spider did not have a hole in is as shown in the drawing. This gave a larger gluing surface. We sued a frame to hold the parts, although once mounted the frame beomes unimportant.

>4. Which speakers/passive radiators/components did you use to build >the subwoofer?

Again, I was with Ford and we had everything custom made. This project was published in SAE and can be obtained. It shows how the theory worked as expected, the +6 dB gains were achived and the lever with one driver outperformed two drivers in about the same enclosure volume, fewer drivers and watts required with the lever.

If only I could get some company to make the actual lever, I know that this would be a popular approach. Maybe someday I will pay for the tooling and do just that. But I have other interests right now.

If you, or anyone else, wants to have these levers made and sold, I would give you rights, they are patented, to do this since I own them for most configurations of advantage.

• Practical lever construction