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Discussion Starter #1
I have been doing research for a few weeks about building my own downward firing subwoofer. I found a site where some else basically gives a step-by-step procedure to build a forward firing enclosure using a Peerless XLS10 10" woofer and 10" passive. The author tested this speaker as a closed box, vented box, and passive radiator box and came to the conclusion that this speaker worked best with the passive radiator box. The project I am planning would work best with a 10" woofer (I think), but I am planning on a rather unique enclosure and I was wondering if i could adapt his plans. I have always been a big sci-fi fan, so the vast majority of my DVD collection revolves around sci-fi. For years the ceter peice of my living room has a cheap, plastic, R2-D2 cooler given to me by my brother. My wife doesnt think a cheap plastic cooler has a place in our living room decor, so I came up with the idea of building a "steam punk" version of R2-D2 as a downward firing subwoofer. To my surprise, she actually likes the idea!
So my first question: How do passives work? Does the passive need to be out in the "open", or will it work hidden under my R2-D2's dome?
I plan on building the main body, and dome out of wood. Difficult, yes but I have built other similar pieces before (on separate projects, not all together).
I am not resigned to using the Peerless woofer, it is just a starting point from which to plan my work. Any ideas to start with? Again, this is just a the very start of my plans, any advice would be greatly apreciated.
 

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The Peerless XLS10 with a PR works best in an enclosure that is the optimum size for that specific applcation. Passive radiators have the same function as ports do in a vented box. The advantage of PR's is the ability to tune to a low frequency in a small enclosure.

If you could determine the internal volume of your cabinet, a proper recommendation can be made as to the right sub for the cabinet, and whether ports or PR's would give the best performance in your application.
 

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Most passives also need to be installed in an vertical orientation. Mounting it horizontal like you want to will cause it to sag. If you could find one that could be mounted horizontal, you would need to create a dome as a grill. It could not be sealed or you would lose all benefit of having a passive radiator.

-Robert
 

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Discussion Starter #4
That helps a lot! Basically, the size of the project is adjustable. So the internal volume can vary from around 30 to 40 liters, plus or minus a little. It sounds to me like a passive would be to hard to work in to my project, so I need a decent driver (but not too expensive) that can work with this volume without a passive. I also think that a sealed case would be easiest to accomadate, but ported may work as well. (Do sealed boxes make poorer woofers in general? I just dont see very many done.) I liked the Peerless driver mentioned because of its cost (aound $150-$200) and the good reviews I read about the quality, but I am defintely open to suggestion! Another question, if I am building a cylinder cabinet with a downward firing driver, does it need to be braced inside like some of the larger square boxes I have seen here?
 

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Check out the Tube-zilla project at The Audioworx for proper construction techniques.

Sealed subs are just as popular as ported models and they sound just as good depending on your goals. As for the Peerless, there are newer subs that sound just as good with more output capability like the Exodus Audio Shiva-X.

-Robert
 

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I missed the 40L limit. The Dayton DVC 12" will work fine in that size sealed enclosure. I ran one in a 1.2cf box for over a year with no issues.

-Robert
 

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Discussion Starter #9
This is primarily for HT, with the very occational music. Would this be an easier project if the volume were greater?
 

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Consider a sonosub for the most bang for your buck and labor. That is using a good 15" sub driver in a ported cylinder enclosure that uses concrete piller molds (i.e. Sonotube). Just the end caps to fabricate using MDF -- so minimal carpentry labor required.
 

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Discussion Starter #14
Thanks guys! all the comments have been helpful so far. I have learned that bigger is better (at least bigger than 40 liters). I did some rethinking and reimagining of the overall project. I can do a 100 liter enclosure. Is ported or sealed the way to go. I have seen a lot of projects here and elsewhere. Ported seems to be the most popular. Is there a simple answer as to why?
What costs can I expect for the amp to run a larger driver? How do I find the right mix for great sound clarity?
 

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Discussion Starter #15
Does the port for a sonosub design have to be on the top? Or can it be ported out the side? Does the port direction have any bearing on the sound (is facing forward better or backwards)? I also noticed most sonosubs designs have a plate attached to the legs 4 inches below the driver. Is this done on purpose?
 

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Is ported or sealed the way to go
Ported has more low end output, which is what you want for HT.

What costs can I expect for the amp to run a larger driver?
That will depend on the subs requirements. State a budget for the sub, once that is picked out and modeled, we'll know what you need.

Does the port for a sonosub design have to be on the top? Or can it be ported out the side?
Top or side, it doesn't matter.

Does the port direction have any bearing on the sound (is facing forward better or backwards)?
No difference between forward or back, as long as the port is not too close to a wall.

I also noticed most sonosubs designs have a plate attached to the legs 4 inches below the driver. Is this done on purpose?
Without a baseplate a high excursion sub can cause the tube to jump. And it looks good.
 

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Discussion Starter #17
Ok, so I need to set a budget... I would like to stay under $200 for the sub. But that is not an absolute limit. If spending just a little more increases the quality of the sub 4 fold, well then I will do it! :scratchhead: I do want to end up with a high quality sub, but I don't necessarily need to wake the neighbors up 3 houses away. :demon: Clean sound is far more important to me than sheer loudness. I am still trying to figure out if I should go with a 12 or a 15 inch. My guess is there is a substantial difference between the two- is there?
 

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Discussion Starter #19
I have downlaoded WinISD myself and have been working with it. I have also been trying to learn what the graphs mean, by reading the info on this site of course! Thanks again for all the great info in on place.
Will the shape of the dome top be of any concern? I mean, does shape affect sound quality?
 
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