Need Help - DIY Built-in Subs

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Comments

  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    Just to get you to visualize things, this is what behind your screen ought to look like ideally, next best thing is to at least have the center behind it. Not any of these in particular but you can see the pattern. I know the guy who owns the last one.


    6e5308b4fdbcc9de905a3268248f76aa.jpg


    Procella%20baffle%20wall.jpg

    MAV_theater_1_web.jpg?1437684667

    klipsch-thx-ultra2-theater-xl.jpg

    14887434637_c3f9f19392_c.jpg
  • scubalabscubalab Posts: 2,971
    Metro - I really appreciate all the input, and I wish I could do some of the things you're suggesting. I need to stay in reality though. :) This is a space in the house we made work for a modest HT. Over the years, I've made small improvements with speakers, different subs, AVR's, amps, etc. They've all been baby steps. I have to say that I've been very happy with each improvement, yet completely understand that there are ALWAYS better things. That said, I'm too limited in the space, and way to far along to change too much at this time. Could I get incredible sound with what you're recommending? I've no doubt I could! Some of those pics look phenomenal, and I'm sure they sound incredible. But, for my space, I only have 9'10" in width in the room. The front door is RIGHT up against the front wall. The ceiling is only 7'4". There is dead space to the back right (bar area)... All of these things create a less than ideal pallet to work with, but it is what it is.

    So, unfortunately, for now, I'm pretty set on the layout of the screen, equipment, and what's going on 'behind the wall'... I just can't take any more steps back and rebuild.

    I'll try to clarify and answer some of your other questions as best I could.

    1. Overall budget?

    Well, I didn't really have a concrete budget at the start, but wanted to keep all the work between $1000 and $1500. That was to be everything - new wall, rack, electrical, new carpet in the room. Well, that budget has been blown as usually happens. Just having to replace my Anthem was nearly all of the budget. So, I'm hoping to keep the subs (drivers, amp, materials for boxes, etc.) at around $800-$900 max.

    2. Is your riser complete? If not can you scoot the thing forward? Your side surrounds need to be at least 90 degrees to the side of the front row if possible, plus if you scoot it forward you could fit two more subs in the back corners at least eventually. Four subs, one in each corner, is about the best you can hope for in terms of smooth response seat to seat.

    The riser is built, but it's completely movable. I built it a long time ago and can very easily reconfigure it. When we get new carpeting in the room, I'm going to have the riser carpeted as well, but it'll still be free floating & mobile. The drawing isn't dead on accurate. The side surrounds are actually directly in line with the front seats. I realize the sketch looks like the seats are WAY behind the side surrounds. That's not the case though. The surrounds are located pretty good... probably too high, but in line with the front row of seats.

    I actually have the room wired with sub cables to each of the rear corners, so adding subs in the back at a later time is not entirely out of the question, however, the whole intention of doing built in subs was to get stuff out of the room!

    3. Can you make the room symmetrical? Right now it is offset to one side. Ideally it needs to be symmetrical with the seats in the middle.

    Unfortunately, no. The room is VERY narrow (9'-10"). The screen is slightly offset to the left to be more in line with the seating being more to the left. Centering the seats would make two VERY narrow walkways around them. It would also crowd access to the bar.

    4. Can you put those rear 7.1 surrounds together more? I think they are spread out too far. Direct radiating speakers that are closer together and firing forward would work better.

    I suppose I could move them closer, but it's not ideal. The back 'wall' isn't there... yet... It's currently open to the sunroom behind it. Eventually, we plan to put sliding doors there to separate the two spaces. The rear speakers could be moved closer together, but they are already very close to the ceiling (I know... not ideal, but that's the best I can do). Moving them closer together would require me turning them on their sides and mounting them RIGHT adjacent to the ceiling.

    So, given the equipment I have to work with, I designed the front wall and AV rack. The only new or upgraded component was to be the subs. I completely understand the advantages of having the front soundstage behind the screen, but with my speakers, I can't do that. Unfortunately, although not ideal, the front 3 are what they are. The L/R will be set at around 4' high on either side of the screen. The center USED to be on the floor (I know... horrible placement). With this build, I'll have it centered and directly under the bottom of the screen. That left the spaces for the subs. I just need to make something work (with what I have) as good as I can (completely understanding that it could always be better)...

    Hopefully that makes sense?
  • Can you at least get that center behind the screen? Even if you didn't swap speakers you could at least just place the thing horizontally behind the screen for now. An AT screen may actually save you money if you don't already have a screen, you can get DIY material from Seymour, same stuff that's at Skywalker Ranch, for like $300 for a pretty big screen. It's about your cheapest option to be honest. Very mild modification on that center 2x4 and you could have something special.

    Also if you could modify anything so that you could pass larger boxes through, you have more opportunities.

    As of right now, the only solution I'd be comfortable with considering your budget is two of the Stereo Integrity 18's in a sealed box plus an iNuke 3000 DSP. You'd be at $797 then could spend $100 on some MDF and hardware. That's about it.

    If you could redo part of the wall to allow larger boxes to pass through, you could leverage a ported box and have more output for less bucks. I think your space is too small otherwise.
  • scubalabscubalab Posts: 2,971
    I could possibly remove the center stud and move the center up behind the screen. I already have a screen and wasn't planning on replacing it just yet. What I'll likely do is reframe just that part (relocate that center stud) for future relocation of the center speaker. I'll run a wire to the area for now. If I do eventually replace the screen, all I'll have to do is cut the drywall out and install the center. At that point, I'll likely just go with an in-wall center to save on depth.
  • I said horizontally earlier but I meant vertically. Horizontal centers are a big compromise. I'd try to ditch that center stud like you said. If it really is load bearing then build a header. Very easy at this point. Later on, not so much.
  • scubalab wrote: »
    If I do eventually replace the screen, all I'll have to do is cut the drywall out and install the center. At that point, I'll likely just go with an in-wall center to save on depth.

    I can see the difference in the thought process better here. You don't need drywall behind the screen. There's no need for it, would only do more harm than good in this situation. Leaving a big area open would allow for larger speakers behind the screen (once you upgraded screens) as well as giving you the ability to pass larger subs through that wall. If you did that, you could do whatever you wanted. Could build two massive ported boxes firing through those cubby holes, would be awesome, basically have the port and driver both on the bottom then build it pretty tall. Basically just like this except move the drivers down.


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  • WLDockWLDock Posts: 2,797
    Yes, that's like building a box to match the in-wall space...the more space the better. Even if you had to work within the studs there are companies that offer options...so anything is possible.
    6c397134c64c77ea04e38816b620e07d.jpg?1456444890

    You are getting some good advice through this thread. Two ported 15's or sealed/ported 18's...make it work! LOL!
    FAMILY ROOM
    HDTV - Sharp AQUOS LC-70LE600U 70" | AVR/Streamer - Onkyo TX-NR3008 | Amp - Parasound HCA-1203A
    Blu-Ray/Media/Gaming - Sony PS3-320GB / Microsoft Xbox One | Broadcast - Xfinity X1 Platform
    Front Spkrs - Coming...DIY Statement II | Center Spkrs - Coming...DIY Statement II | Rear Spkrs - Artison Portrait LRS
    Sub - DIY Stereo Integrity HT 15 | Sub Amp - Dayton Audio SA1000
    Wire - Audioquest Type 4, BJC Belden 5000 | HDMI - BJC Belden | Power Cables - Pangea | Surge - Monster
  • scubalabscubalab Posts: 2,971
    I agree wholeheartedly that there has been some great advice here, but I need to reinforce that I cannot... I repeat CANNOT go any deeper than a 3-1/2" studded wall behind the screen. I can go approximately 2' deep below the screen and next to the AV shelves. I can squeeze out another 1.5" in width in box size giving me a space 20.5" wide x 24" deep x 36" high PER BOX. Taking 2" off each dimension for MDF and enough of a gap to slide the boxes into the cubby holes, that gives me 8.01 c.f. Bracing would reduce that, as would the port (if I go ported). But, surely 6-7 c.f. should give me a good sub ported or sealed?

    Additionally, the wall behind the screen is fairly fixed. I may not have been clear, but behind that wall (in the guest BR) there will be cabinets mounted for storage (above the counter that will sit above the AV rack and subs). So, removing the drywall on the BACK side of that wall is not an option nor does it gain me anything since there will be cabinets there. At best, I could at some point move the front sound stage behind an AT screen, but those speakers would need to be in-wall speakers no deeper than 4" (in the blue area in the picture below).

    Here's a cut-away/cross-section view of the wall. It should clearly illustrate the area I have to work with as well as the area that is off-limits (per the wife!)

    0kgv8kg811rl.jpg
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    scubalab wrote: »
    surely 6-7 c.f. should give me a good sub ported or sealed?

    With 7 cubic feet internal you should be able to copy the recommended design for a 15" ultimax tuned to 18 hz. I like sealed 18's myself but if you really don't want to put two more in there, and don't want to spend any more than necessary especially on an amp, then an iNuke 3000 DSP with two 15" ported ultimax's tuned to 18 hz should make you happy. That ought to have a better low end than two sealed 18's, would fit in your budget, and should fit in that space. You really only need about 6.6 cubic feet plus a little for bracing for this. Bracing probably would only add 0.1 cubic feet no more than 0.2 depending on how you do it. You may be able to make it bigger though, you've got 7.73 cubic feet internal to work with if you have 1/2" clearance on each dimension and use a double baffle.
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    Pretty sure if you made a box with these panel dimensions, you'd end up with 7.73 cubic feet internal. After driver, port, bracing, you'd end up with about 7 cubic feet net internal after displacement just guessing. Could model your own thing or shrink this to match Dayton's recommendations.

    Three 20x35.5 baffle and rear

    Two 20 x 21.25 top and bottom

    Two 34 x 21.25 sides

  • WLDockWLDock Posts: 2,797
    edited March 2016
    Two ported 15's would be the idea...but there are MANY out there more than content with two sealed 15's or 18's. Yeah, a four sealed 18" in the corners would be great for all of us. However, even myself can't really get a second sub against my long front wall given what's planned for the room (Wine cabinet, wall shelf, etc). Maybe, I can get a second one behind the couch.....if I can stealthily slip it pass the Mrs. LOL!

    So, try to go ported for a dedicated 99% Theater...but large sealed can work for some....a little low end boost helps.
    FAMILY ROOM
    HDTV - Sharp AQUOS LC-70LE600U 70" | AVR/Streamer - Onkyo TX-NR3008 | Amp - Parasound HCA-1203A
    Blu-Ray/Media/Gaming - Sony PS3-320GB / Microsoft Xbox One | Broadcast - Xfinity X1 Platform
    Front Spkrs - Coming...DIY Statement II | Center Spkrs - Coming...DIY Statement II | Rear Spkrs - Artison Portrait LRS
    Sub - DIY Stereo Integrity HT 15 | Sub Amp - Dayton Audio SA1000
    Wire - Audioquest Type 4, BJC Belden 5000 | HDMI - BJC Belden | Power Cables - Pangea | Surge - Monster
  • EndersShadowEndersShadow Posts: 17,163
    WLDock wrote: »
    Two ported 15's would be the idea...but there are MANY out there more than content with two sealed 15's or 18's. Yeah, a four sealed 18" in the corners would be great for all of us. However, even myself can't really get a second sub against my long front wall given what's planned for the room (Wine cabinet, wall shelf, etc). Maybe, I can get a second one behind the couch.....if I can stealthily slip it pass the Mrs. LOL!

    So, try to go ported for a dedicated 99% Theater...but large sealed can work for some....a little low end boost helps.

    Yup @WLDock we are relooking at ported... I'd like sealed as its just so dang easy lol, but I do agree ported will be better till below port tune so we are going to look at the graphs and go from there...

    PS you still got those Chane's?
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    WLDock wrote: »
    there are MANY out there more than content with two sealed 15's or 18's.

    What people don't seem to realize about sealed is that the response just falls off a cliff below 40 hz. Look at measurements then basic response here:

    http://www.data-bass.com/data?page=system&id=116&mset=128

    For home theater you really need to get down to at least 18 hz. At that point in this example you are 12 db down from 40 hz. To put it in perspective, you have to double your amplifier power just to get 3 db more. Quadrupling the power is like 6 db. 8x the power = 9 db. You're looking at 16x power just to break even. That's not really reality because your sub would be blowing up or at least distorting its head off at that point.

    Yes cabin gain helps a ton, but still, sealed subs takes muscle to make it work well. Unless you can get a ton of power and a lot of cone area, you'd be better off going ported and tuning it as low as you can get away with. Two sealed 15's with a cheap amp would be pretty weak down low for home theater.
  • WLDockWLDock Posts: 2,797
    MetropolisLake...you are right, I got nothin' However, I do love JL Audio's basic paper on the subject. The OP should read it if he has not already: http://www.jlaudio.com/header/Support/Tutorials/Enclosure-Type+Performance+Comparison/Tutorial:+Enclosure-Type+Performance+Comparison/287535

    Myself, I've always loved the sound of a sealed 12"-15" for a dual purpose music / HT sub. However, the best route would be to have a convertible sub in which you plug the ports. I'm thinking about it....
    WLDock wrote: »
    Two ported 15's would be the idea...but there are MANY out there more than content with two sealed 15's or 18's. Yeah, a four sealed 18" in the corners would be great for all of us. However, even myself can't really get a second sub against my long front wall given what's planned for the room (Wine cabinet, wall shelf, etc). Maybe, I can get a second one behind the couch.....if I can stealthily slip it pass the Mrs. LOL!

    So, try to go ported for a dedicated 99% Theater...but large sealed can work for some....a little low end boost helps.

    Yup @WLDock we are relooking at ported... I'd like sealed as its just so dang easy lol, but I do agree ported will be better till below port tune so we are going to look at the graphs and go from there...

    PS you still got those Chane's?
    Yeah, man we are going to do the dang on thing if I can ever get some stuff done. My weekends are busy.

    FAMILY ROOM
    HDTV - Sharp AQUOS LC-70LE600U 70" | AVR/Streamer - Onkyo TX-NR3008 | Amp - Parasound HCA-1203A
    Blu-Ray/Media/Gaming - Sony PS3-320GB / Microsoft Xbox One | Broadcast - Xfinity X1 Platform
    Front Spkrs - Coming...DIY Statement II | Center Spkrs - Coming...DIY Statement II | Rear Spkrs - Artison Portrait LRS
    Sub - DIY Stereo Integrity HT 15 | Sub Amp - Dayton Audio SA1000
    Wire - Audioquest Type 4, BJC Belden 5000 | HDMI - BJC Belden | Power Cables - Pangea | Surge - Monster
  • EndersShadowEndersShadow Posts: 17,163
    edited March 2016
    If we go with ported, here are some of the parts if we go with a regular circular port:

    Outside flared port opening - need 4
    Internal flared port opening - need 4
    Port connecting ring - need 8
    Regular PVC pipe for the rest of the length with maybe a 45 degree elbow.....

    I reached out to someone in order to try and turn those ports into a single slot port of sorts as its easier to build one of those. If I hear back I will let you know.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • I reached out to someone in order to try and turn those ports into a single slot port of sorts as its easier to build one of those. If I hear back I will let you know.

    Just google "port calculator". Ideally for a non-flared port you need at least 35.6 square inches of port area. Using the 20" wide baffle I pulled out of my rear earlier, you could use a 2.5x18.5" internal port and have 46.26 square inches of port area which is more than enough. It would be 49.25" long which would take up 1.7 cubic feet of air space, giving you 7.7 cubic feet total, which seems pretty convenient since he had 7.73 total. This would leave you 6 cubic feet of space for the driver which is what Dayton recommended. You'd have to model it but this may actually turn out better, because it seems that Dayton was having to use poly-fill, which slows down the air velocity in a ported box, and since the area on this is nearly twice what they are using, huffing and whatnot should not be an issue.
  • Regular PVC pipe for the rest of the length with maybe a 45 degree elbow.....

    I don't think normal PVC plays well with Precision Port stuff. They sell their own pipe and I think you have to use that if you want a good fit. Cheapest way to do it is to get normal PVC, a metal bowl, heat up the end of the pipe, press the pipe down on the back of the metal bowl, and flare the thing yourself.
  • scubalabscubalab Posts: 2,971
    Walt - Thanks for the link! I'm 'getting my read on' now.

    Dan/Metro - If flared port tubes are better, I'm fully capable of working with PVC & ABS (I plumbed my entire house...) so it may actually be easier than building a slotted port with MDF. I'm open to either... whichever's best.
  • scubalab wrote: »
    If flared port tubes are better

    Flared port tubes keep the port from huffing/chuffing when the port velocity is high. If your port area was big enough then this shouldn't be an issue in the first place. A round port that's barely big enough needs to be flared though.

    Slotted ports are definitely the cheapest route which is why they're popular. Only thing that would seem more difficult is designing the box in the first place. It would make more sense if you had a 3D drawing. I just do it all in my head so I imagine is sounds like gibberish to other people.

    If you wanted to flare your own out of a PVC pipe, this is how you do it.



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