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  • MTM Disadvantages

    I’ve been thinking about building a kit speaker of the MTM configuration, but I’m wondering about the drawbacks of such a design.
    I know they have several advantages—like increased power handling and lower distortion (on the woofers) due to the load sharing of the double units. I would think if this were the ultimate answer, all speakers would be of this configuration.
    So what are the disadvantages of such a design that should be taken into consideration?—other than the larger cabinet. Thanks

  • #2
    I've made - but not designed - two MTMs. I think the only disadvantage is a slightly odd look and the issue that as the tweeter should be at ear level, the speaker has to be mounted slightly higher than a TMM; depending on the speaker's use of course.

    Other than that, I don't see any disadvantages, mine sound great. Paul Carmody's Classix 2.5 (TMM) are on my 'to do' list and it will be interesting to compare them with our MTMs.

    Geoff
    Last edited by Geoff Millar; 05-01-2019, 01:50 AM.

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    • #3
      Two more drivers to purchase, two more holes to machine, a little extra wiring...

      Seriously though, the MTM configuration has a narrower vertical lobe. In other words the sound changes more dramatically when you go from sitting at ear level to standing up compared to a MT. But this narrower lobe has an advantage too, reduced ceiling and floor bounce.

      I have designed and built 3 or 4 MTM's. If you keep the vertical spacing between the drivers as tight as possible the vertical lobing effect is fairly minimal.
      Craig

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      • #4
        Originally posted by Ilovspkrs View Post
        I’ve been thinking about building a kit speaker of the MTM configuration, but I’m wondering about the drawbacks of such a design.
        I know they have several advantages—like increased power handling and lower distortion (on the woofers) due to the load sharing of the double units. I would think if this were the ultimate answer, all speakers would be of this configuration.
        So what are the disadvantages of such a design that should be taken into consideration?—other than the larger cabinet. Thanks
        All speakers are a compromise, and everybody has a little different idea of what the best approach is. So, don't expect one design to conquer the rest any time soon. Having said that, I'm seeing a lot more MTMs these days than say, 10 years ago. I went MTM to minimize floor and ceiling bounce, and for better integration with the horn at the center of the MTM. It works better in my situation certainly, better clarity.
        Francis

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        • #5
          Unless really small overall, not optimum for nearfield PC desk type usage.

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          • #6
            Originally posted by djg View Post
            Unless really small overall, not optimum for nearfield PC desk type usage.
            Practically speaking, that may be the biggest disadvantage.
            Francis

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            • #7
              The alternative, if you want similar power handling, is to use a larger woofer and a smaller midrange. This increases cost and complexity, but will generally result in a more natural sound, with greater similarity between direct and reflected sound. The fact that in an MTM your treble is being reproduced by a driver which is something like 16" in the vertical dimension is the biggest disadvantage to MTMs (and how much can you really decrease the edge to edge distance of an MTM with 6" woofer?) However, for home theater, where output and intelligibility are more important than absolute transparency and naturalness, it is a good compromise.

              See my thread exploring MTMs for use as center channel speakers in a horizontal orientation. For this use they are really really bad.

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              • #8
                Dunno civit. My MTMs are eerily natural and realistic sounding.
                Francis

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                • #9
                  Originally posted by civit View Post
                  The alternative, if you want similar power handling, is to use a larger woofer and a smaller midrange. This increases cost and complexity, but will generally result in a more natural sound, with greater similarity between direct and reflected sound. The fact that in an MTM your treble is being reproduced by a driver which is something like 16" in the vertical dimension is the biggest disadvantage to MTMs (and how much can you really decrease the edge to edge distance of an MTM with 6" woofer?) However, for home theater, where output and intelligibility are more important than absolute transparency and naturalness, it is a good compromise.

                  See my thread exploring MTMs for use as center channel speakers in a horizontal orientation. For this use they are really really bad.
                  This is just incorrect.
                  craigk

                  " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

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                  • #10
                    Originally posted by civit View Post
                    The fact that in an MTM your treble is being reproduced by a driver which is something like 16" in the vertical dimension is the biggest disadvantage to MTMs
                    That's not a disadvantage. The vertical pattern control that results is an advantage, one of the reasons for their popularity.

                    www.billfitzmaurice.com
                    www.billfitzmaurice.info/forum

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                    • #11
                      Originally posted by billfitzmaurice View Post
                      That's not a disadvantage. The vertical pattern control that results is an advantage, one of the reasons for their popularity.
                      Well, I agree. I tried D'Appolito's original BW3 quadrature topology on mine, which gives a huge vertical lobe, but the image was 8 feet tall. I went to LR4, like he did, because the image is precise and believable.
                      Francis

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                      • #12
                        Originally posted by craigk View Post
                        This is just incorrect.
                        Craig, can you elaborate so that the original poster (and some of the rest of us) can know why?

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                        • #13
                          Originally posted by civit View Post
                          See my thread exploring MTMs for use as center channel speakers in a horizontal orientation. For this use they are really really bad.
                          I think we can all agree with that. They were never intended to be placed horizontally. Not sure it's relevant to this conversation.
                          Francis

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                          • #14
                            Originally posted by billfitzmaurice View Post
                            That's not a disadvantage. The vertical pattern control that results is an advantage, one of the reasons for their popularity.
                            +1
                            Don't listen to me - I have not sold any $150,000 speakers.

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                            • #15
                              I think the trade-off we are identifying is between power response and vertical polar response. This website shows the consequences of the MTM design pretty well:
                              http://www.musicanddesign.com/Power5.html

                              The MTM has a tightly controlled and symmetrical vertical polar response, but the reverberant field will have a big suck out around Fc. I'm not sure this is a terrible thing, but I tend to prioritize smooth power response in my designs.

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