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  • DIY center channel with LOTs of limitations help?

    Hey all! Been a while for me here on TT….built what I needed but now there’s been a change out of my control and a new center channel speaker is required for OUR 5.1.4 family room. So the better half spent the better half of a few months to find the/her ‘perfect’ console to place our 70” TV on top of. Needless to say, there’s no place to incorporate a center channel into it…….the only option is on top of it. It’s higher than I would have chosen (wasn’t offered a choice or voice) so all I have is 3.5” inches of height to work with……there is no compromise here……sorry :(

    So this leaves me with horrible options of an MTM or MMTMM with 3” drivers and a dome. The MMTMM is probably neccessary to reach the volume of the other mains and system….we do enjoy movies at cinema levels…….the MTM option with such small midwoofers will probably not make it

    OR…….an interesting driver with very peculiar specs……the Dayton Audio LW150-4 https://www.parts-express.com/Dayton...4-Ohms-295-255
    …..a pair in an upward firing configuration below the screen and a central tweeter forward facing…..maybe angled slightly to reach ear height at the listening distance.

    If the response measurements are to be accepted, this 6” woofer has flat response on and off axis to 1.8khz. It’s extremely shallow so an enclosure of 3” in height is easily doable and a pair of these will easily hit our reference volume requirements. It can fit between the TVs legs and i won’t have to raise the screen height at all. If this all checks out, the only other hurdle I can think of is a tweeter robust enough to cross at 1.8khz with the power handling to work.

    Would love to hear your thoughts on the LW150 and if this is possible…..and it’s GREAT to be back…..I feel so useful again with a DIY prospect!

  • #2
    Those are tough dimension constraints! You're far more skilled and experienced than I, so I'm sure what I'm about to write is stuff you've already considered...

    If you didn't need cinema-level output, I would lean towards the Tectonic 3-inch BMR instead of a traditional tweeter and cross that over to your pair of LW150s (which I've never heard). I don't think you would get the SPL you want out of any small wideband driver that would let you cross below 200 hz and most are pretty bad off-axis.

    My mother-in-law has a ZVOX TV base that uses ~2-inch wideband drivers with a horizontally mounted bass driver. It sounds better than it should. That makes me think it is possible to find a compromise, especially if you can you some DSP/EQ to mask some of the FR warts and keep your expectations reasonable. Looking forward to seeing where you take this!

    Comment


    • #3
      Would a pair of 3" DMA80-4 in a 2.5liter MTM (tuned around 90-95hz) work, assuming they'd pair to the subwoofer around 80hz and reach [email protected] (without BSC)?

      I'm worried the ~45degree angle needed to fit a 6" woofer into a ~3.5" height might make an even lower XO point important...not sure though.
      I think the pair of LW150's would have about 2-4db more headroom at around 105-107db (a noticeable but modest amount), but the LW150's would have a horizontal lobe like a ~15" woofer from the MTM configuration which might move the desired XO point even lower.
      Last edited by LOUT; 05-03-2022, 11:10 AM.
      My first 2way build

      Comment


      • #4
        I'm in the same boat as you, it wouldn't happen to be a Vizio TV? I've been contemplating putting the midwoofers behind the TV and ducting their output through something like a reverse waveguide that tapers from large to small. The issues I'm having are how to model it in Hornresp and what shape to make the taper, i.e. curved, folded, straight taper.

        I'd like to get some input on solving the center channel with no clearance issues. I'd like to avoid putting the TV on blocks to raise it up.

        Sorry to semi-hijack your thread.....

        Comment


        • #5
          Originally posted by devnull View Post
          I'm in the same boat as you, it wouldn't happen to be a Vizio TV? I've been contemplating putting the midwoofers behind the TV and ducting their output through something like a reverse waveguide that tapers from large to small. The issues I'm having are how to model it in Hornresp and what shape to make the taper, i.e. curved, folded, straight taper.

          I'd like to get some input on solving the center channel with no clearance issues. I'd like to avoid putting the TV on blocks to raise it up.

          Sorry to semi-hijack your thread.....
          No worries……thanks for sharing. What I’d REALLY like to do is go virtual on the CC, but my mains are too wide……I use them for music and when they’re too close to the TV, the stereo image falls apart.

          Comment


          • #6
            Originally posted by LOUT View Post
            Would a pair of 3" DMA80-4 in a 2.5liter MTM (tuned around 90-95hz) work, assuming they'd pair to the subwoofer around 80hz and reach [email protected] (without BSC)?

            I'm worried the ~45degree angle needed to fit a 6" woofer into a ~3.5" height might make an even lower XO point important...not sure though.
            I think the pair of LW150's would have about 2-4db more headroom at around 105-107db (a noticeable but modest amount), but the LW150's would have a horizontal lobe like a ~15" woofer from the MTM configuration which might move the desired XO point even lower.
            Thanks for the suggestions! It looks like I’d need a 4” high box for the drivers you suggested……the cutout is 3” so I’d need a half inch for top and bottom enclosure thickness.

            My thought wasn’t a sloped baffle, but use the LW150 mounted flat on top…..upfiring. It appears in specs to operate like a BMR with flat on and off axis response……but you know what they say about appearances! Lol

            Comment


            • LOUT
              LOUT commented
              Editing a comment
              The DMA80's frame (not counting the front baffle) is a little under 3", so it might be possible to build a 3.5"-tall box with relatively deep channels cut at the top/front and bottom/front where the woofers would mount to make room for them. It'd thin those particular areas to a little over 1/4", but I think the small size and contoured shape of the grooves should cut down on the chance of resonances...though I'd definitely lean toward plywood instead of MDF for the tops/bottoms in that situation.

              Looking at the LW150's off-axis response specs from PE, I wonder if you're right. It does have an oddly tightly-grouped on/off-axis response.

          • #7
            The other option I’ve considered is a very wide enclosure…..like a sound bar…..with three MT segments, LCR but all just playing back CC content. The spacing could be as much as 15” between segments. That would likely have enough power handling as well. There’s also a three way option with the drivers I mentioned acting as woofers only, but I think a three way is outta my capabilities to design an XO

            Comment


            • #8
              Are the Lw-150s facing towards you? If they're facing away or down-firing that kinda defeats the point of using them for midrange. If they are facing towards you, you could do an mtm with 2 LW-150s and an SB26ADC-C000. The latter is a tweeter from SB acoustics that can be had for 54$ on madisound or meniscus that absolutely does what you want it to. If you cross it at 1800 with a 3rd order the power handling should be very good. If you want to stay parts express, the DA32TX from peerless should also do the trick quite well.

              Comment


              • #9
                Originally posted by Thephantompsychic View Post
                Are the Lw-150s facing towards you? If they're facing away or down-firing that kinda defeats the point of using them for midrange. If they are facing towards you, you could do an mtm with 2 LW-150s and an SB26ADC-C000. The latter is a tweeter from SB acoustics that can be had for 54$ on madisound or meniscus that absolutely does what you want it to. If you cross it at 1800 with a 3rd order the power handling should be very good. If you want to stay parts express, the DA32TX from peerless should also do the trick quite well.
                The LW 150’s would be facing upwards toward the screen…..their specs suggest perfect off axis performance to 1.8khz.

                i have an SB29 on hand…..pretty sure it can do 1.8 as well……and the RS28 new version?

                Comment


                • #10
                  Maybe some of these weird speaker modules, some dirt cheap buyouts.

                  https://www.parts-express.com/speake...peaker-modules

                  Comment


                  • #11
                    I know you have very specific constraints, but is there ANY way of Wall mounting the TV somewhat above the actual stand?

                    That opened up TONS Of options in my one set up. That extra several inches.

                    Comment


                    • #12
                      I'm surprised no one has mentioned this yet, but what you are proposing is more or less a different version of Linkwitz's Pluto, so in theory it could work. Maybe some info there will help with your decision.

                      Since you are thinking outside of the box, another solution might be a horizontal curved line array with smaller fullrange drivers. You'll be breaking some rules but if done well, this might also work in your situation. My sister had a similar problem after a reno to her living room, she left only about the same amount of space for the CC as you could fit a DVD player into, I think the height limit was about 2 1/2". So I picked 6 of the little Aura 2 inchers and did this with them:

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                      In the end I found the slight lack of HF response from those drivers to be just a bit unsatisfying so I added a small tweeter to each side of the box which technically is a real no-no but which I found better in the end. I think it took me to about version 68 before I was happy with the xo though. Anyways, pick a small fullrange driver with a better HF response and you shouldn't need a tweeter. You may need to cross your sub up to around 100Hz with these though depending on the driver selection. And I guess you'll have to figure out if this type of concept will meet your SPL demands too. Just a thought anyways.

                      Comment


                      • #13
                        Originally posted by mobius View Post
                        I'm surprised no one has mentioned this yet, but what you are proposing is more or less a different version of Linkwitz's Pluto, so in theory it could work. Maybe some info there will help with your decision.

                        Since you are thinking outside of the box, another solution might be a horizontal curved line array with smaller fullrange drivers. You'll be breaking some rules but if done well, this might also work in your situation. My sister had a similar problem after a reno to her living room, she left only about the same amount of space for the CC as you could fit a DVD player into, I think the height limit was about 2 1/2". So I picked 6 of the little Aura 2 inchers and did this with them:

                        Click image for larger version

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                        In the end I found the slight lack of HF response from those drivers to be just a bit unsatisfying so I added a small tweeter to each side of the box which technically is a real no-no but which I found better in the end. I think it took me to about version 68 before I was happy with the xo though. Anyways, pick a small fullrange driver with a better HF response and you shouldn't need a tweeter. You may need to cross your sub up to around 100Hz with these though depending on the driver selection. And I guess you'll have to figure out if this type of concept will meet your SPL demands too. Just a thought anyways.
                        Any further details you care to share? Wiring? Xover?

                        Comment


                        • #14
                          Originally posted by mobius View Post
                          I'm surprised no one has mentioned this yet, but what you are proposing is more or less a different version of Linkwitz's Pluto, so in theory it could work. Maybe some info there will help with your decision.

                          Since you are thinking outside of the box, another solution might be a horizontal curved line array with smaller fullrange drivers. You'll be breaking some rules but if done well, this might also work in your situation. My sister had a similar problem after a reno to her living room, she left only about the same amount of space for the CC as you could fit a DVD player into, I think the height limit was about 2 1/2". So I picked 6 of the little Aura 2 inchers and did this with them:

                          Click image for larger version

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                          In the end I found the slight lack of HF response from those drivers to be just a bit unsatisfying so I added a small tweeter to each side of the box which technically is a real no-no but which I found better in the end. I think it took me to about version 68 before I was happy with the xo though. Anyways, pick a small fullrange driver with a better HF response and you shouldn't need a tweeter. You may need to cross your sub up to around 100Hz with these though depending on the driver selection. And I guess you'll have to figure out if this type of concept will meet your SPL demands too. Just a thought anyways.
                          Thanks for sharing and your thoughts! I’d considered those Aura drivers but as you discovered, the HF response isn’t great

                          I was thinking about Pluto when I came up with the upfiring drivers……the LW150’s on paper have a better off axis performance than the Pluto woofer…..they seem to act much like a BMR.

                          I’m wondering if I can’t use the Peerless/Vifa DX25btg …..the one with the buck magnet at 460hz Fs……..1200hz 2nd order electric with the natural rolloff…..3rd order acoustic?
                          If i fit the tweet between the woofers facing fwd, I can probably horn load it a bit……maybe enough to boost the lower end a bit

                          Comment


                          • mobius
                            mobius commented
                            Editing a comment
                            I would think that a low xo frequency and very good phase matching at the xo are going to be really important for this design in terms of maintaining a consistent off-axis response. That might mean the hardest part is going to be designing the tweeter placement so you get a relative acoustic center for the woofers that works well with your xo choices. I'm thinking you'll have to do a mock-up or 2 to get that figured out right.

                            That tweeter looks like a great candidate but you might also want to look at some tweeters that are already horn loaded by Wavecor, SB and Seas off the top of my head.

                        • #15
                          for davidroberts,

                          I'm not sure how suitable this design would be for other people because it's for a very specific application - sitting in a wall cubby hole so essentially in-wall with no bsc and less than 3" tall using 1/2" and 1/8" material. But since you asked, I wired the Auras in mirrored pairs: going left to right - 1 & 6, 2 & 5 and 3 & 4. So pairs wired in series and all 3 pairs wired in parallel, plus a paralleled pair of Dayton ND16FA-6. Impedance minimum was about 3ohms and F3 is up around 250Hz.

                          Here's my in-room measurements at 0*, 4*, 12*, 20* and 25* from a couple of meters away with no gating so a slight downward sloping response towards the HF's is what you're looking for instead of something dead flat. Room reflections are adding a few ripples along with the inherent comb filtering (like I've been trying to imply, it's a bit of a compromised design). Measurements included a little sub as well.

                          Click image for larger version  Name:	pic V64 FR + sub 0, 4, 12, 20, 25 degrees.JPG Views:	0 Size:	85.5 KB ID:	1486058
                          Not perfect by any means with a fair amount of variability between measurements but it sounded pretty good to my ears no matter where I was sitting on the couch and my sister is no audiophile by any stretch of the imagination anyways. This was actually replacing a cheap little Sony HT-in-a-box CC that she was using and that had only 1 tiny 1 1/2" x 2 1/2" driver in it so just about anything with decent drivers in it was going to sound better.

                          And the xo:

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                          In the end, I ended up with something fairly simple with just 6 parts despite all of my best attempts to make it more complex. My sister had quite a lively room and I actually found it a touch bright in that environment so if that's the case for you, experimenting with a 1 or 2ohm resistor in front of the tweeters might sound better.

                          Not sure who this is going to work for but if you are interested, have at her. Maybe the only other thing to know is that with the front array, drivers 3 & 4 were angled back 2.5*, 2 & 5 were angled back 7* from those and then 1 & 6 were also another 7* back from those. Original width was about 19.5" but then I added 2 side modules to accommodate the 2 extra tweeters. The sleeve wrapping with end caps I stole from Definitive Tech and Paradigm to make my sister happier. I thought it looked better seeing the drivers though.

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