Question about passive radiator design

[aduncan]

I'm brainstorming on different ideas for a box rebuild for my Tang Band 8" sub. This sub seems to like somewhat smaller boxes and getting a good large port is difficult because the length of the port frequently exceeds all the other box dimensions. So I was thinking a passive radiator may be a solution, but I know so little about them. Does anyone have any information or advice, or perhaps could point me in the right direction to learn more? And is a passive radiator even a practical solution to the problem of tuning a small box to a low frequency?

[max]

Hi there,
if you look down a bit I put a review of the TB w8-1363 subwoofer in a .5 cu.ft. sealed. The result is already imoressive. However the TB should work better in a ported or PR design (like you mentioned)... Well if a sub works good in a small box, it won't have a problem if you make it work in abigger.... i.e. the tb should work good in a 1.5 or 2.0 cu.ft. as well. As for PR you probably need 2 10' and the price factor will kick in...
Having said that I've been talking to Wolf about the same issue and I know he's working on that project, so be patient and see what he worked.
Meantime I would suggest either go sealed or go ported on a larger box.... being able to fit the port.
Max

[Wolf]

In a .5ft^3 box with the 1363 (My apologies if you used the 740C), you'd need 2 XLS10" 400g passives, and they're $80 a piece. The problem with the lesser expensive PR's is that they're either too large in diameter themselves, or the Xmax is limited. When using more than 2 of the Dayton (SDVC8/10) PR's the tuning requires so much added mass they can't support it evenly, and would fail assuredly. This is even though the Xmax would be within the safe range unweighted. With the 2 400g(+mass) PR's, you'd achieve an F3 of 29.11Hz at it's lowest point. I've modeled the driver numerous times and ways, and have measured the driver on the WT2 for actual specs.
Golopagus,
Wolf

[duanebrown]

http://i17.photobucket.com/albums/b69/duanebro/25L_25Hz_mini_sub_box.gif


Try a slot port. This is one design I've come up with:
(I've also designed a 15L box tuned to ~35hz)

[aduncan]

That's some good info on the PR's. I may or may not go that route. But I am interested in the idea of simply making the box bigger. A larger box looks to be easier to port (I'm using WinISD). However, I believe I had read somewhere that larger boxes can translate to less power handling. I'm using a 150W plate amp. Any concern about power handling issues with the 740C with 150W to it? And please forgive me if these questions seem simple - I'm still new at this.

> I'm brainstorming on different ideas for a
> box rebuild for my Tang Band 8" sub.
> This sub seems to like somewhat smaller
> boxes and getting a good large port is
> difficult because the length of the port
> frequently exceeds all the other box
> dimensions. So I was thinking a passive
> radiator may be a solution, but I know so
> little about them. Does anyone have any
> information or advice, or perhaps could
> point me in the right direction to learn
> more? And is a passive radiator even a
> practical solution to the problem of tuning
> a small box to a low frequency?