Small Woofer, Small Box, huge Port or PR

ani_101

ok, so I am trying to squeeze a whole lot of woofer into not a lot of box. A EBS tune gets me nice an low, but the port is very long - Even getting the port diameter small as low as 1" it is still very long - increasing it to 2 gets me to almost a meter for the port length.

So I started looking into PRs big and small. The PR seems to get me nearly there - the tune is not as low as the port, but acceptable. The problem is the amount of weight I need to add to these tiny PRs. Is there some rule or thumb or some way to know how much weight is too much?

I am looking at the Dayton 6.5 inch, the Peerless 5.14 inch and the Dayton inch" PR. Are there any other cheap 5" - 8" PR out there that i should be looking at? 

Thanks and Regards
Ani

Face

You may need multiple passive radiators.

ani_101

I am going with 2 of the 5.25 or the 6.5 vs 1 of the 8. The PR sd x xmax is more than twice of the woofer sd x xmax. But when I use one or double it, the weight goes up correspondingly...

Face

You're correct, I had that backwards...as for other available PRs, have you checked Madisound?  https://www.madisoundspeakerstore.com/passive-radiators/  Page 2 has a 6.5" Seas PR, but it's kind of expensive.

greywarden

This actually had many more results than I was expecting, pretty sure most of them come without specs, though  

http://bit.ly/2cwEBff

jr@mac

I would submit that if one were to be willing to do considerable experimentation, any number of 6.5" to 8" woofers can be modified into passive radiators fairly easily. The Dayton Classic line offers a low Fs and a lot of mechanical excursion capabilities.

I think if someone were willing to execute and document this experiment, it would be a feather in their cap...

PWRRYD

I have a ND104 that died.  So I knocked its magnet off.  Was thinking of trying it as a small PR.

jhollander

When I tore apart those little TV speakers they just had a rubber surround glued to a metal plate as a PR.  You can buy surround kits.  J. Bagby started a PR design but don't think anything came of it (?)  I don't think he used a spider either. 

So a complete DIY PR would be a cool project.  Any good reference materials around?

isaeagle4031

I have the PRs that Eminence built for Jeff. Not sure Jeff is going to pursue it further, but I am.

jhollander

I seem to recall a JB home built design where he use of a surround on both side of a piece of wood?

JasonP

jhollander said:

I seem to recall a JB home built design where he use of a surround on both side of a piece of wood?

I recall something like that too. Given enough support, the spider should be unneeded.