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Advice on in-wall/built-in HT subwoofers

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  • Advice on in-wall/built-in HT subwoofers

    Good Afternoon!

    Over the past few weeks, I've been working on getting my media room set up, and the final piece of puzzle is the subwoofers. I have the L/C/R speakers all mounted in-wall behind an acoustically transparent screen, and am planning to install dual in-wall subwoofers as well. From what I can tell, the majority of off-the-shelf in wall subwoofers are pretty poor, so I plan to do some DIYing.

    The room is 13x17 with 12 foot ceilings. The wall that the screen is on abuts an attic space, so there is plenty of space to build into as needed. The only drawback being that the attic space is not climate controlled, so the studs are enclosed on both sides, which will make it more difficult, but not impossible, to mount an enclosure to the studs. I'll be powering the subs with two NHT SA-2's - not super strong but respectable amps.

    Most of the time we're watching at moderate volume levels, so I don't need anything that will set off car alarms down the block, and I don't want to install anything so large, that I would have to cut out a stud (15" on center) and put a header in, so probably 12" woofers max. I'm thinking of a budget of around $300 for drivers.

    What would you guys recommend - drivers, bass alignment etc... I've been kicking around doing dual-opposed drivers in an infinite baffle setup, doing two of the new ultimax 8s with a slot port, trying a DIY in-wall enclosure with the Dayton LS12-44s, or even just using a pair of Tang Band W6-1139SIF's I have laying around. I'm not much of a Home Theater or subwoofer buff, so I'd value your thoughts.

    Cheers!

    Joe

  • #2
    For me, right now, the RSSHF-4s are on sale, and would each look great in a 2.5cf box w/a 4" Precision Port, that's 20" long. Fb and F3 in the mid 20s.
    The LS12s can have the same rolloff, but in 3.5cf (each) w/a 4" port that's 9" long (Fb of 28Hz). They have a slight edge in sensitivity, but most of that would be negated by your amp's slightly lower output into 8 ohms. The RS has more Xmax headroom (and COULD take more power).

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    • #3
      Good Morning!

      Well, I ended up finding a pretty good deal on a pair of the Ultimax 10" on eBay, so I'm planning to try those in slot ported boxes tuned to the low 20s.

      I'll share the progress of the build once it gets underway!

      Joe

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      • #4
        Click image for larger version

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        This is a slotted cab I designed (using my own DATS parms) for use w/a Dayton plate amp.

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        • #5
          With a set of UM 10's, I'd run manifolds and go infinite baffle instead of messing with boxes behind the wall. It's easier and IB subs sound awesome. JMHO.

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          • #6
            Originally posted by make_some_noise View Post
            With a set of UM 10's, I'd run manifolds and go infinite baffle instead of messing with boxes behind the wall. It's easier and IB subs sound awesome. JMHO.
            I would definitely consider going this route. Do you have a picture of a setup like this?

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            • #7
              Well a manifold is a box that is open on one end but is a little easier to deal with and integrate. Here is someone's IB manifold with a couple of large drivers. The end going through the wall is simply open into listening room and the attic is the "enclosure". Not all drivers can do IB, but the UM's can. You might look into the following forum if you are interested in doing an IB install: http://ibsubwoofers.proboards.com/

              Click image for larger version

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              • #8
                Got the manifolds built and everything installed today. I haven't had time yet to do much listening, so I'll hold off for now on commenting on the sound.

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                • #9
                  Nice work! Should look good once finished.

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                  • #10
                    With an adjacent attic, I think a IB is the ideal way to go. But, a pair of 10s is a little small for an IB, don't you think?
                    - Ryan

                    CJD Ochocinco ND140/BC25SC06 MTM & TM
                    CJD Khanspires - A Dayton RS28/RS150/RS225 WMTMW
                    CJD Khancenter - A Dayton RS28/RS150/RS180 WTMW Center
                    CJD In-Khan-Neatos - A Dayton RS180/RS150/RS28 In/On Wall MTW

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                    • #11
                      I got the screen back up and watched some clips from a few movies to get the subs dialed in. I have them crossed at 80hz to the balance of the system. Overall I'm pleased with the sound. They are definitely capable of hitting hard, and they blend very well into the other speakers.

                      My only concern at this point is that they seem to get a little sloppy at higher excursion levels. I suspect that the issue may be with the NHT-2s. I'm going to try powering them with my Teac AI-3000, which is a much stronger amplifier in all regards, to see if they behave better with more/better power.

                      Cheers!

                      Joe

                      Comment


                      • #12
                        Good Afternoon!

                        It's been a while since I posted on the board, and I thought I'd give a quick update on this project. It's been kind of a saga of different amplifiers, and I really should not have tried to cheap out from the beginning....
                        1. I started with 2 NHT 2s (each powering 1 of the ultimaxes). It worked, but sounded a little sloppy as noted above. Eventually one of the NHTs started having some issues with its volume knob, and was switching back and forth between the current volume level and max volume sporadically.
                        2. So I ditched the defective NHT and ran them for a few weeks wired in series to 8 ohm on a single NHT 2... obviously this was even worse.
                        3. In the intervening period, I started a subwoofer project for someone else, which required me to buy a Dayton SA230, so I swapped that in for the NHT. The SA230 actually did a great job considering it was only pushing about 150 watts into the 8 ohm load.
                        4. Recently I bought a Behringer EP4000, which is rated at 2 x 1,400 watts at 4 ohms to power the two ultimaxes. I thought that the fan noise wouldn't be an issue, as I already have fan noise from my projector. I was mistaken, the fan noise on this unit is excessively loud. I swapped the stock fan for a much quieter model, and was back in business. This amp made a HUGE difference in performance, and sounded drastically superior to the SA230 setup. The timing was perfect, as The Last Jedi just came out, so I ran it through its paces on that. The one drawback was that in order to level the base volume with the rest of the system (or at least for my taste) required the volume on the EP4000 to be at its max. I could have left well enough alone, but I'd like to have a little head room in order to turn the subs up (or down) depending on the source material.
                        5. Yesterday, I installed a MiniDSP 2X4 between the receiver and the Behringer in order to get more control of the gain into the amp and to shape the bass signal. After some initial testing, this option definitely allows me to get more output from the system, but I haven't yet had time to play with a lot of different EQ settings.
                        In the end, the NHTs were a terrible idea, but I'm pretty pleased with the Behringer + MiniDSP combination, and I would recommend it to anyone looking for a lot of power and versatility at a reasonable price ~$450 with the fan mod.

                        Cheers!

                        Joe

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                        • #13
                          I'm surprised the minidsp has the ability to drive the behringer with its .9v output. The ability to precisely eq an IB sub, IMO, is critical. In that reguard, the minidsp will make a ton of difference in sound. Back in the day we used the behringer feedback destroyer pro as a parametric eq. and took measurements with a RadioShack spl meter to flatten things out.

                          http://techtalk.parts-express.com/fo...khanspires-but
                          http://techtalk.parts-express.com/fo...pico-neo-build
                          http://techtalk.parts-express.com/fo...ensation-build

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                          • #14
                            Originally posted by Kornbread View Post
                            I'm surprised the minidsp has the ability to drive the behringer with its .9v output. The ability to precisely eq an IB sub, IMO, is critical. In that reguard, the minidsp will make a ton of difference in sound. Back in the day we used the behringer feedback destroyer pro as a parametric eq. and took measurements with a RadioShack spl meter to flatten things out.
                            Would the HD version provide significantly better performance with its higher output voltage?

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                            • #15
                              I was thinking the ep needed around 2volts for full output, but the manual states a little over 1 volt. One sure way to find out if the minidsp 2x4 is clipping its .9v output, or input, as both are a little limited ... connect it to your laptop with the usb cable and monitor it. The easy to use minidsp software has impressed me, its limited input/output range has not. If you don't need the HD version, that's money that can be spent elsewhere ... plus a six pack of the good stuff.
                              http://techtalk.parts-express.com/fo...khanspires-but
                              http://techtalk.parts-express.com/fo...pico-neo-build
                              http://techtalk.parts-express.com/fo...ensation-build

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