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Modula MTM BOM & Crossover

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  • Modula MTM BOM & Crossover

    I have spent all morning going over the designs that were posted and trying to develop a "up to date" BOM for the Modula MTM. Below is what I got so far. I thought it might be useful to others? Feel free to correct or comment... Jeff
    Attached Files

  • #2
    Sorry about the resolution, I had to posts as .gif to lower file size... Jeff

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    • #3
      While of no great import, PE is showing a May re-stock date for the RS180S-8 used in the original design. If you don't need shielding and can fine tune bass alignment by ear, it's a wash.

      Have fun,
      Frank

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      • #4
        I was reading there almost drop in replacement for the non shielded?
        http://www.htguide.com/forum/showthread.php4?t=38268

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        • #5
          These cost more than the Khanspires and the statements!!

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          • #6
            Prices have went up on just about everything. Also note that I have wood, veneer, brushes, glue, etc... on the list. Cost of crossovers and speakers are $534.50 without shipping. If I went with the Dayton Audio RS722 Kit 302-857 it would be $378.00 without shipping. So $156.50 to have a better sounding crossover?

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            • #7
              You're looking at Modula MTM, one of many RS180-based MTM designs. Here are another 5, including the Modula with the RS28A tweeter:
              http://rjbaudio.com/RS180MTM/rs180-rs28-mtm.html

              I see Jon Marsh's Modula-series designs as his attempt at no-holds-barred loudspeakers using "value" drivers. RS180's are a lot cheaper than comparable Usher, Seas, ScanSpeak, Acuton drivers and he did designs for several tweeters, but without backing off on the XO design complexity or component quality requirements.

              As part of this series, Jon (as Evil Twin, a Darth Vader avatar) also created the NatalieP design, which won't make sense until you realize Jon's a Star Wars fan (and knew casting Natalie Portman as Princess Amidala was a waste of talent). As Evil Twin puts it: "The crossover is the crux- how to deal with the dark side of the RS180 (it's high level break up modes) while retaining a transparent midrange and acceptable component cost. This somewhat unorthodox solution is proposed." Only ~$50 per for the standalone design.

              I built a pair of NatP's, but also used a NatP sideways as a CC - against recommendations. I recently upgraded to the Modula MTM CC. One on-wall XO cost $142, plus $126 for the Scan-Speak D3004/602010 tweeter, but my stone-eared wife commented on the improvement in dialog clarity. Musically, I didn't notice much of a difference.

              I recently priced out another pair of NatP's at >$400 for the pair, drivers, components and binding posts, comparable to the RS722 kit price less the foam. I also built Roman's 2.5-way XO, about $90 per, but can't speak to cost of other designs.

              Have fun,
              Frank

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              • #8
                fbov, thanks for the background on the different designs and forum member. Pretty funny story and in a weird way it makes sense, lol. Bit of a star wars fan myself..

                I did look at the link provided when I was researching everything. I noticed L5 in Jons design is 1.4mh and in the rjbaudio comparison its 1.2mh? I also contemplated doing the Nat P design, I have read a lot of good things about the design.

                I guess I'm just in a rock and a hard place. I am limited to what I know which is the Lou C topaz's I built and a pair of Tri-trix which I thought all sounded great. I was hoping to at least match that if not sound a little better.

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                • #9
                  Originally posted by jmik26
                  I guess I'm just in a rock and a hard place. I am limited to what I know which is the Lou C topaz's I built and a pair of Tri-trix which I thought all sounded great. I was hoping to at least match that if not sound a little better.
                  I researched similar builds, and I'm planning to go with the AviaTrix, which should be an upgrade to the TriTrix you like and are only $250 for components. I'm planning to build a curved sided MLTL variation for a little more low end extension, plus I wanted towers. I have no idea how they would compare to the Modula MTM or Nat P's, just figured I'd throw another option out there. I'm hoping to order soon and will be doing a build thread.

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                  • #10
                    I can give you some idea how they would compare.

                    I'm not familiar with Lou C's Topaz, but the TriTrix/Aviatrix would be hard to ignore. I've been to a few DIY events, even taking my NatP towers, and there are a few consistent things that provide a basis comparison.

                    Driver Size, Rated Power, Parts Cost (pair)
                    Tritrix DC130, 30W, $120
                    Aviatrix ND140, 40W, $250
                    Modulae RS180, 60W, $400

                    All MTM's, so rated power doubles, but you can't beat cone size and the resulting advantages in sensitivity. As you go down the list, sensitivity increases and power handing increases. Advantage Modulae (i.e. RS180/RS28A-based design) on both counts.

                    As you go down the list, cost roughly doubles as the driver size increases(especially if you need a CC). Disadvantage Modulae only to the extent that you get what you pay for.

                    Subjective Impression (what I think)
                    I've not heard ND140's, but did hear my NatP in direct comparison with a Dayton Classic 4-way at Dayton DIY (now MW Audio Fest). Others agreed that there was no question which had better sound quality. This jives with my other observations that I like low-distortion drivers in well-designed implementations. None of PE's similar drivers (DA-series, DC-series) that I've heard have sounded as good as the RS-series.

                    To be honest, this comparison is all hindsight. I picked an RS-based design only because 2x 7" drivers have comparable cone area to a single 10" driver that I was replacing. I picked the NatP only because Jon described it as a "good value." I literally ordered parts June 30th and had a CC speaker built by July 4th. A sideways NatP, of course, but the first step on the path to learning about speaker design and what works in my HT.

                    Today, the Aviatrix might be my top choice.

                    It all depends on your ears and what's important to your enjoyment of the audio program. And your budget. There are many happy TriTirx owners out there.

                    Have fun,
                    Frank

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                    • #11
                      Thanks for the details fbov. I started reading on the Nat P and will finish tonight, maybe make a BOM tomorrow and decide by the weekend. I have the tax return burning a hole in my pocket so I figured I would go with the Modula but I might go Nat P and pour a little more into my receiver.

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                      • #12
                        So I have been reading up on the Nat P's and they are pretty particular about using certain gauge coils and some capacitors of higher quality. In the BOM in post one for the Modulas I posted, is there any crossover components I should upgrade? I am going to do some reading and try to find the answers but I thought I would throw it out there for some help. Thanks... Jeff

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                        • #13
                          I might be way of base on this idea but here goes. When I called Solen the tech guy told me If I went with Dayton RS drivers I would land up spending the same amount of money as I would with SEAS Prestige drivers. The added cost with the RS drivers would be in the additional components for the crossover. I thought this was interesting and then noticed that Zaph's Waveguide used very few components in the crossover. Maybe you pay one way or another to get to a certain level of sound.

                          Paul Carmody's "Core" doesn't seem to have hundreds of dollars in the crossover. I wish he would to a TMM version of this design, if I did a MTM I know my wife would wonder if I was drunk when I drilled the holes for the drivers. As you all know they are wonkey, not symetrical.

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                          • #14
                            Originally posted by jmik26
                            is there any crossover components I should upgrade?
                            As per the designer:
                            Use Solen caps and AWG 14 Solen inductors, with Mills resistors, but the price is certainly higher, and differences may not be audible in most systems.
                            I believe elsewhere he states that 1/2 the value of the tweeter caps, to use audio theta caps. But of course that is lots more cash...
                            Michael
                            Chesapeake Va.

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                            • #15
                              Thanks for the help guys. The Nat P's are looking better and better... Jeff

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