Home Theater Forum and Systems banner

Placement options for passive radiators

15K views 21 replies 4 participants last post by  rf5000 
#1 ·
Hello All,

I am building a subwoofer with (1) SDX15, (2) 15 inch passive radiators, and (1) EP1500 for power. Normally when building a box one would put the subwoofer up front and then each passive radiator on the left and right sides. But, for the box I am building, this will not work. Is it okay to put the subwoofer up front, one passive radiator opposite the subwoofer in the rear, and then one passive radiator facing down? So there would be no passive radiators on the sides. I am concerned that it would affect the sound, bass extension, etc in any way? Also, if I flush mounted the down facing radiator, would I have to worry about clearance or space underneath for it? Of course the subwoofer will be off the ground on four legs. Thanks.
 
#3 ·
So there will be no difference in sound in any aspect? Installing the sub firing down with the passive radiators in front and back will not effect any chracteristic of the sound? Is there a certain clearence I should have from the subwwofer and floor if I point it down? Or just as long as it doesn touch the floor I will be good? This may sound stupid, but does any actual bass come from the sub itself? What I mean is if I point it down with an inch of clearence from the floor, will that produce less bass or have a muffled sound?
 
#8 ·
Is that because of the excursion of the subwoofer? 4 inches off the ground would look a little weird, wouldnt it? Is there anyway around this? I was already making the bottom two 3/4 inch sheets thick so that I could sink it in. I guess I could make three 3/4 inch sheets thick and sink it up even further but then I lose interior volume, right?
 
#9 ·
It's because of the amount of air the sub moves. It needs clearance so there isn't any restriction. Regarding your PM about box size, here is 3 different sizes with 1000 watts and a hi-pass filter at 15 hz. As you can see the bigger the box the more low end output. With that being said there's nothing wrong with 3.8 cu.ft. if that's as big as you can go. With room gain you should get 112 db at 20 hz.

Text Line Technology Font Screenshot
 
#10 ·
In a 3.8 cubic foot box, the sub does roughly 110 DB and the 6.5 cubic box does like 113 DB. Would I really be able to notice a difference? Also at 25 hz it is about a 3 DB difference. Is that going to be a real noticeable difference in your opinion?
 
#15 ·
I am making a curved box that is going to be similar to corock's box with multiple stacked sheets, leaving the wall thickness at 1 inch. The box is going to be flat up front and flat in the rear with round sides. Now this box alone with stacked sheets, not even considering the extra quarter inch thickness(1 inch walls compared to 3/4), would be way stronger then a normal square box made of 3/4 mdf. Do you really think I need internal bracing? Also, I am up in the air now with what sub to build. My idea with the subwoofer up front and the two PRs on the sides wont work so well with a curve sided sub box. I could work but would be a very difficult making curved grilles, etc. This is why i posed these questions of rear mounting and bottom mouting the sub and PRs, but that doesnt seem like its going to work either because I dont want a sub box four inches off the ground. So this brings me to more questions, should I consider ported or sealed? I could return the PRs I bought and do a ported sub or sealed sub. What do you think? Would I need a more powerful amp then the EP1500 if I went sealed to get the output I am looking for, right? Or if I went ported, what would be the best design? See, I want to do all of this because I want to build a sub with curved sides. I wish I could just mount the sub up front and then mount one huge PR in the rear but that wont work either because I would need like a 30 inch PR for 15 inch sub!!

I just think the curved sides look so cool and dont look homemade as much.
 
#17 ·
Another idea I was considering, mounting the PRs front and rear, and then mounting the sub internally facing down or what ever direction I need. Has anyone ever done this? So basically the subwoofer would be mounted inside the box and the only openings would be for the fornt and rear PRs. Would that kind of be like bandpass but using PRs instead of ports? Or am I looking at this all wrong?
 
#19 ·
The baffle should always be at least double thick, and yes you need internal bracing. FWIW raising the sub up on 4 dowels looks quite professional. It seems to me you are making this more difficult than it really is:whistling: Now start making some sawdust or else:paddle:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top