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Discussion Starter #1
Hi guys, this is my first thread on these forums and I suppose it's only appropriate that I'm asking for help. :)

For the past few weeks I've been spending a lot of my time reading the AVS Forums DIY Subwoofer/Speaker forum contemplating building my own subwoofer. Don't ask me why but, from the very beginning, I was considering one of the Exodus Audio products for the driver. I didn't know much about them (I still don't know what a lot of the stats really mean) and there are certainly a lot of competing products, but, I guess Kevin just makes his products look crazy tempting on his website... it's the best idea I've come up with so far.

Anyway, I was considering the 27"x20"x27" dual 4" ported box design that I've seen on this forum and AVS but realized that my wife really wouldn't approve of something so big in our already cluttered living room and she really wouldn't like the idea of adding a ep2500 plus an EQ. The ep2500 and EQ were suggested to me so that I would have an upgrade path of sorts... basically assuming that I would catch the DIY bug and want/need the power for future projects.

At this point I'm seriously considering the 91L sealed design (plus a 500W plate amp... the Oaudio one was suggested) in the shiva_app.pdf. It looks like I should be able to get some pretty killer performance out of it while still not building a box that will eat my living room. If that goes well, I could probably build a second one in the future for some added boost.

Okay details: HT will be the primary use. Probably 80% movies 15% games 5% music.
Room dimensions: 15x13x8 (right side) and 17x13x8 (left side) just about the entire right wall (from the sitting position) is bay window while the left side has two half walls that partition the living room from the kitchen.

First question: Any flaws in the logic here? I'm assuming that between the plate amp I'm looking at and room gain, I should be able to get really respectable extension at enjoyable SPLs. My present system is a HTIB that isn't very good so, by comparison, this should completely rock my world right?

Question 2: Are there any established designs for this cube? I am no carpenter (relying on the help of friends and family to help here) nor am I a particularly gifted mathematician, so, if I can start off with some established designs, I run a lower risk of introducing math errors on top of carpentry errors. :)

Anyway, thanks for the help and I'll thank you in advance for the patience.

Chris
 

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Hi Chris and welcome! 91Liters is a 19.5" external cube. If your budget can afford it, I'd suggest adding a pair of 12" passive radiators to get the most output from the amp and sub combination in the room size you have. Here's a SPL graph comparing the two.Yellow is sealed and Green is with the PR's. The PR's are $67 each.

http://creativesound.ca/details.php?model=APR12



Shiva-X PR.JPG


As for designs, I built a 18" cube with PR's, yours would be 1.5" bigger. The Build is documented here:

http://www.hometheatershack.com/forums/diy-subwoofers-sealed-ported/16761-creative-sound-solutions-sdx10-sub-kit.html
 

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Discussion Starter #3 (Edited)
Hi Mike, thanks for the suggestion sir! I honestly hadn't considered PRs just because it was adding complexity and cost to the build, but, from your thread it doesn't look too terribly difficult... nor too terribly expensive.

Questions:

Does adding a PR (or two) make the sub act like a ported sub in so much as you really want to add filters to avoid damaging the driver (or does the amp have those filters and I just missed it)?

Also, it looks like we're getting similar performance out of this design as we might with a larger ported sub. Is that kinda the idea here and how do you think this would stack up to a 180L ported number? I'm learning a lot, but, some of this still comes across as pretty arcane to me!

Do you have to worry about resonance and port chuffing with PRs, or, are we adding two PRs to eliminate those issues?

Oh! And Kevin's suggestions on the shiva_app.pdf mentions adding polyfill to all of his suggested designs and you're using foam. Any particular reason for one versus the other?

Thanks again for the help.
 

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PP's aren't complex, you're just cutting 3 holes instead of one and mounting the drivers. The advantage of these PR's is the tuning is adjusted from the outside of the sub by adding washers. It doesn't get any simpler.

PR's make a sub act like it's ported, there are no resonance or chuffing issues. The O-Audio amp has all the filters you need to protect the sub. The above model was shown with the 20 hz high pass filter which also has 4 db of boost, and the PEQ set to cut a slight amount of the boost at 20 hz.

In 180 Liters the sub would have more low end extension due to the bigger box size. in 91 Liters the PR's don't displace much volume compared to what ports would, in a smaller then optimum box you need all the volume you can get.

Polyfill is a mostly used in sealed subs, it can also be used in ported subs to tame a peaky response and to lower the tuning a bit. Egg crate foam is a can of worms, some say it doesn't work to tame a "boomy" sounding box, some say it does. I've always used it.
 

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I'm in the process of updating some documentation for the Shiva-X that includes a couple Passive Radiator builds. I don't know anything about Bob's PR but I wouldn't recommend it for the Shiva-X. The PR-15"s are going to be a better choice and I'll be discounting them with the package so that they are cheaper than the above listed 12" PR.

Hang tight until tomorrow and I should have the documentation done. The base dimensions for the smaller version is 18" x 21" x 21" but you can trim some width off that because I'm using two layers of 0.75" MDF for each driver mounting surface.

Kevin Haskins
Exodus Audio
 

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Here is the rough and dirty. If you guys could do a quick check for errors and give me any feedback that would be much appreciated. I will upload the cabinet drawings and dimensions tomorrow. They fit best on their own PDF. I'll link them in the documentation once I get it done but I'm out of time today.

http://www.diycable.com/main/pdf/Shiva-PR.pdf

Oh... pricing for the package:

$235 Shiva-X + One PR-15"

$295 Shiva-X + Two PR-15"s

The package is going to include the correct resistor values for the Parts Express BASH amp so that the subsonic filter is correct for this design and all mounting screws for the driver & PR-15s. You should be able to build this entire package for <$500. An alternate amp would be the HSPA500 amp by PE. You wouldn't need to modify the subsonic filter and you can use the PEQ boost to pick up the couple dB of boost as per the design.

Kevin Haskins
Exodus Audio
 

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Discussion Starter #8
That's a pretty fantastic deal Kevin! Thanks for posting it. Hopefully I'll be able to place an order in the next few weeks!

Mike, thanks for suggesting the PR sir. It really looks like what I'll be going with since it's giving me extension and spl that I think I'll be thrilled by, and, it won't be completely dominating my living room which was my wife's main desire.
 

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I'm pretty sure that a new house or going back to school would take priority for her, but, I can try to be persuasive. ;)

Heh... that would be an interesting thread: What would you play to try and convince your wife/SO that new equipment was "necessary?" Deliberately manipulative/romantic/beautiful music... some romantic movie that happens to have a really dynamic score and sfx... could be interesting.
 

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I'm pretty sure that a new house or going back to school would take priority for her, but, I can try to be persuasive. ;)

Heh... that would be an interesting thread: What would you play to try and convince your wife/SO that new equipment was "necessary?" Deliberately manipulative/romantic/beautiful music... some romantic movie that happens to have a really dynamic score and sfx... could be interesting.
I've found that my wife likes the speakers if they look nice and fit the decor of the room. Part of looking nice is that they are not large. ;-) That drove some of my design choices for the Kepler. It had to pass the wife test.

I'll say this much, my wife spends more time listening to our speakers at home than I do. She is there all day while I'm slaving away in the warehouse. I think once your wife hears them, and if they fit the room, she will be positively thrilled to have them. Mine is and nobody fails to comment on how they sound.

Kevin Haskins
Exodus Audio
 

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Well, I'm pretty confident that the speakers I have chosen are no where near the Kepler's, but, they are a huge upgrade for us and that will be thrilling in and of itself. I only have the center channel at this point, but, the quality of sound and the sensitivity difference are already audible. Once I have the left and right speakers in the house, it's on! :)

And yeah, so long as the sub I'm building isn't too big, looks decent, and sounds like money well spent we'll be fine. Having an idea of just how my present sub is makes me suspect that this new one is going to blow us away!
 

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I apologize for resurrecting an old thread, but, I just wanted to say that I pulled the trigger on the Shiva-X and 2 PR-15s late last week. The amp should arrive today and I couldn't be more excited!

I'll just have to wait and see if I have the patience for a rookie build thread!
 
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