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All,

Good morning. Ok so this is a new construction home and we have a dedicated media room where we do not want to have visible subwoofers for design purposes. The room is 17x17. the entire room has a conditioned crawlspace under it. In this room there will be an 11.2 or 11.3 Atmos system. I want some heavy hitting bass. So far we have a 12" TruAudio bandpass subwoofer that will be located under the room in a crawlspace and be vented out in the right corner of the room. The original plan was to use this TruAudio subwoofer and then place a SVS PB-16 Ultra inside a wall pointing into the media room. See, there is an adjacent room where we could build a cavity inside some cabinets that this subwoofer could sit in. In the adjacent room it would actually be inside the cabinet, so not really visible from either of the rooms, just the face would be visible from the media room whereas we were going mount a grille on the wall to hide it. This plan seemed all fine until I talked to SVS. They said that even though we had the woofer itself and the ports pointing into the media room, it would still have tons of output behind it and on the sides of it in that cabinet in the adjacent room. We do not want this. We don't want the adjacent room pounding with bass every time the SVS is playing in the media room. So I'm searching for another option. I thought of copying the style of the TruAudio subwoofer and building another bandpass subwoofer to hide below in the crawlspace and then porting it into the media room. But if I did this, I would want to build something that has a ton of output. Thinking of 15" to 18". I'm just nervous because it will be a one shot type situation. Where I wont really be able to test it in the room until its installed and construction is complete. I talked to James Loudspeaker because they build subwoofers like this. They said that you really lose no output by doing this (bandpass&ported) rather than having the subwoofer actually sit in on the floor in the room, so that is good news. I want to make sure it has a ton of output, something that is equivalent or close to the SVS PB16. Would you guys be able to help me with this?
 

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Building a diy subwoofer that would outperform a PB16 is not difficult at all, integrating it into your room under the circumstances you loud may be difficult.
 

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Building a diy subwoofer that would outperform a PB16 is not difficult at all, integrating it into your room under the circumstances you loud may be difficult.
yeah, but this is what I'm trying to accomplish. So basically a bandpass subwoofer that is located under the room and ported into the room. I would like to use 6" port tubes and I'm guessing I would need dual tubes.
 

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Building a diy subwoofer that would outperform a PB16 is not difficult at all, integrating it into your room under the circumstances you loud may be difficult.
To add, what size subwoofer should I be looking at? I have a tone of room in the crawlspace, but at the same time don't know if I want a 4' box either! You think a 15" subwoofer would be good or should I be looking at like an 18"?
 

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yeah, but this is what I'm trying to accomplish. So basically a bandpass subwoofer that is located under the room and ported into the room. I would like to use 6" port tubes and I'm guessing I would need dual tubes.
Sorry, more information. i actually have two locations where I could come up through the floor in that room. So technically I could do two separate 15" bandpass subwoofers, or like one 15" and one 18", or something like that.
 

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Other than the round ports have you looked at the Devistators? They are a horn/6th order BP. You might be able to build them and set under the floor or build in to the floor. They com in varying sizes from 12's to 24's depending on how loud you want.
 

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Other than the round ports have you looked at the Devistators? They are a horn/6th order BP. You might be able to build them and set under the floor or build in to the floor. They com in varying sizes from 12's to 24's depending on how loud you want.
Yeah, the could work but only if I could convert them to ported tube vents. This is a high end home of over 8000 Square Feet so I don't want to do anything weird or makeshift. I want some nice, neat and professional
 

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You may also want to consider a contractor.
 

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Look into infinity baffle for in your crawlspace. You're not going to like how big of a hole you need, though. If I remember correctly, the cross sectional area of the manifold opening needs to be the same as the cone area.
 

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Look into infinity baffle for in your crawlspace. You're not going to like how big of a hole you need, though. If I remember correctly, the cross sectional area of the manifold opening needs to be the same as the cone area.
I don't think an infinite baffle will work. See, I don't want exposed subwoofers in the crawlspace. All i'm looking for is someone to help me with a design like these attached pictures
 

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I think your best bet is multiple 10" or 12" subs. The issue with 15s and 18s in this situation is that the vent is too small compared to the surface area of the driver and ports and so you'll end up with very high air velocity out of the vent (it could be audible). This doesn't mean you can't dig lower than a PB16 or not match it in output, rather it'll just take a couple subs to get there. You should also be concerned about room modes, especially because your room is a square. Multiple subs will help with that. I suppose I'd suggest something like two Dayton UM12s in ported enclosures tuned low to start with. Vent them in opposite corners of the room. If that's not enough output for you, build two more and place them in the other corners. Does that seem like a reasonable plan?
 

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I do not agree with the 6in ports in the floor. I am only mid-level DIY and think it will all sound muddy if you have subs under a suspended floor that vibrates from the subs below. Instead try, say...two 12in-15in horn subs (Randy J) with the horn coming through a custom slot in the floor with a custom floor register (the johnson636 contractor reference).



See below for ideas.
 

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I do not agree with the 6in ports in the floor. I am only mid-level DIY and think it will all sound muddy if you have subs under a suspended floor that vibrates from the subs below. Instead try, say...two 12in-15in horn subs (Randy J) with the horn coming through a custom slot in the floor with a custom floor register (the johnson636 contractor reference).



See below for ideas.

This is the route i was going. Get som nice cnc milled floor registers made to complement the design of the room.
 

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@Randy_J yea if he can afford an 8k sq ft home, a few more bucks for custom floor ports should be sitting in his wallet! Right @thegroup?
Thanks guys but not really the point. I already have these, see attached. They are not the James ones but the ones from TruAudio so very similar but accept a 6" port hose. I was going to have the subwoofer bandpass box sitting below the subfloor and then have the tubing run up inside the wall and port out with the vent assembly. See attached. If needed I could do two 6" port tubes running up inside the wall and have two vent assemblies. This is what I'm trying to work with
 

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that was a joke! I would assume it would work, you probably just need to worry about getting the port length correct. I have a few slot port designs completed but no flared ports, so I cannot comment on using a flexible tube as a port. Someone else with more experience will need to chime in.
 

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that was a joke! I would assume it would work, you probably just need to worry about getting the port length correct. I have a few slot port designs completed but no flared ports, so I cannot comment on using a flexible tube as a port. Someone else with more experience will need to chime in.
Thanks. I know there are several high end manufacturers that build subs like this, so I'm assuming it works great. Its the same concept as some do in car audio. They have the subs located in the trunk that then have the port tube vented to the interior of the vehicle. Another option would be just to push the couch forward a bit more and locate two narrow retail subs behind the couch. Like maybe two of the Monolith 15" because those are taller and narrower. it would still give about 15' from sitting area to the TV. See attached. The red is a couch, the blue are subs, the purple is where TV will be located. The only thing I don't like about this is having to move couch forward as we were originally only going to have it about 6" away from back wall. Disregard the "22", that is just a lighting location
 

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Thanks. I know there are several high end manufacturers that build subs like this, so I'm assuming it works great. Its the same concept as some do in car audio. They have the subs located in the trunk that then have the port tube vented to the interior of the vehicle. Another option would be just to push the couch forward a bit more and locate two narrow retail subs behind the couch. Like maybe two of the Monolith 15" because those are taller and narrower. it would still give about 15' from sitting area to the TV. See attached. The red is a couch, the blue are subs, the purple is where TV will be located. The only thing I don't like about this is having to move couch forward as we were originally only going to have it about 6" away from back wall. Disregard the "22", that is just a lighting location
Or if I wanted couch even closer to the wall, I could do two 12" subwoofers. Maybe like two JL 12" Fathoms? That should really rock a 17x17 room? or are there better options?
 

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