Passive Radiator

[thebigwaldo]

What does a passive radiator do?

There's one here. http://www.adireaudio.com/Merchant2/...ory_Code=30.10

Just curious

[ChameleonGreen]

A PR is pretty much a sub without any motor stucture. Meaning, you can't make it move with electricity. A PR setup is basically a cross between a ported box and a sealed box. First of all, you have to know that any driver creates sound on both sides of it's cone. If you had two rooms seperated with a wall and an open speaker, it would sound basically the same in both rooms.

With a;
Sealed box, the back waves stay inside the box creating back pressure allowing the sub to hit more precise and somewhat deeper.
Ported box, the back waves are allowed exit the box via the port and they help reinforce the front waves giving you a better bass response which is usually about 3dB louder than an equal sealed system. For a sealed box to make the same output as a ported box, you have to give it twice as much power as the ported box, thus ported is more power efficent in a way.

Now, in a passive radiator setup, you have a sealed box with a powered sub and a PR driver. Generally you want the PR driver to have twice the cone area as the powered sub. Now, instead of the backwaves exiting via the port, they instead force the PR out as pressure increases inside the box from the powered sub moving in, and when the powered sub moves out the vacuum pulls the PR back in. What you get here is one sub playing the front waves, and another playing the back waves. The output response of a PR setup is very similar to that of a ported one, however is not going to give you quite the same amount of SPL as a ported driver. The output is also similar to that of a sealed box because the cones are better controlled than in a ported box, but it's still not going to be quite as precise as a sealed box and it will lack some of the depth feel that a good sealed setup yeilds.

[thebigwaldo]

Cool, I kinda though of it like that but wasn't sure on the specifics.

But I was thinking it would be like having a box with 2 subs and having one wired opposite the other so they cancelled eachother (did it once by accident).

Thanks for the clarification.

Jeremy