Project NEXUS... A timbre matched family of Hi-Fi/HT speakers

Discussion in 'DIY Speakers and Subwoofers' started by Matt Grant, Feb 10, 2014.

  1. Hi, hoping for some help. I am building the MTMWW tower speakers, and am up to making the crossover. On the PCB boards designed by Matt there are codes printed for each component. What do these mean? I am thinking they have something to do with what component joins to what?? I can easily place each component the same as the photos above, but am looking for an easy diagram showing what component joins where for this configuration. Any help appreciated.
  2. Did you miss the crossover schematic for those on post #6? That shows how the crossover components are wired up.

    Otherwise if you bought the PCBs from me I include a layout diagram for the parts.
  3. No I did see the schematic and should be able to work it out. I have just seen some schematics that show the components drawn in position with each connection drawn in. Just looks a lot easier to follow. First time doing this and don't want to make any mistakes.
  4. This might help then:
    Nexus MTMWW Tower PCB component layout + Traces.png
  5. Awesome, that is perfect Matt, thank you very much. Just one more question in regards to the crossover coils. I noticed the 0.1mH and the 1mH have a centre wire and an outside wire on your diagram. With the 2- 0.4mH coils which way do the run? ie which is the centre and outside wire in you schematic?
  6. It does not matter which way the leads are run, there is no polarity to the inductors.

    When I am installing coils like that I usually position them so that the lead length to the through holes is shortest whichever direction that might be for a certain brand or value of coil.
  7. Hey Matt

    I have fallen in love with your Nexus project and im seriously looking into building them. It will be my very first try at DIY speaker building so i'm somewhat of a newbie. I choose your project so i didn't have to design everything from scratch so I would be reasonably sure to be successful and because I like you have used Dayton Audios the way you have.

    Being from Denmark I have redesigned your speakers into metric dimensions and taken the liberty to make the towers into a square design - but I've run into a issue sourcing the 1-5/8" ID x 4-7/8" L Flared port you are using for the small TM's - I can only get that from PE in the US, which is a bit of a pain. I cant read directly what frequency you have tuned you port to, but i'm shooting for 60Hz. My/your box size is 7,07L internal volume (internal dimensions W150mm D206mm H268mm) and i will build them out of 3/4"/19mm MDF. I'm able to get a 1-7/8" ID x 5-5/8" L Flared port, a 1" ID x 4" L Flared port or a 1-1/2" ID x 4" L Flared port. What is my best potion in your opinion - I've looked into calculating the port on my own but i'm worried about chuffing since I honestly have no clue what i'm doing. Hope you can help me with this final step. Thanks in advance.

    Hers a picture of your Nexus speakers (the Danish version). I think they will end out being in white high gloss finish.
    Screen Shot 12-09-18 at 07.25 PM.JPG
  8. The enclosure for the TM design is tuned to about 60hz.

    These ports should work for the TM design if they are easier to get:

    I think the speakers will look great in a gloss white finish!
  9. #109 LexxDk, Dec 10, 2018 at 3:43 PM
    Last edited: Dec 10, 2018 at 3:55 PM
    Hey Matt.
    Thanks for the quick reply. Yes this port is way easier to get. I have to buy stuff there anyway. This really helps me out.
    Should I keep the full length of the port?
    By the way, do you have any pictures of the dampening inside the different speakers? If not, I'm planning to follow the advice from Troels Gravesen homepage about cabinet damping.

    Thanks for the help
  10. Yes keep the port at full length.

    I don't have many good images showing how I put the damping in these cabinets but the guide by Troels is a good approach and would work well for these cabinets.

    Here is the MTM (older narrower cabinet design) where I have the inside lined with recycled denim insulation.

    And one of the Tower cabinet design as well when I was stripping it down to re-apply the veneer.
    LexxDk likes this.
  11. You can get the same port tube from a EU store:

    You want this item:

    It would be great if you share your metric plans. In my country we also use metric system.
  12. Hey mga2009

    Sure ;) I can share them. I'm currently working on finishing the drawings as I want them. I'm planing to route out tracks for my internal braces and I'm currently working on that. What are you looking for - I mean how detailed planes are you looking for?

    My thinking in my design revolves around copying Matt's internal volume. I really wanted to make my speakers to have a similar design. I was shooting for a design with rounded sides, but it was not possible to make with my current set of tools. My second design idea was a "squared" evolution of the rounded design - but it became too big a pain to cut out :p so I abandoned that idea as well. Anyway - the first picture is a sketch of the internal volume of the two first design ideas.
    Screen Shot 12-14-18 at 07.25 PM.JPG

    I came up with the design by first calculating the internal volume of Matt's original design, then drawing a model of the internal volume in CAD (I used autodesk inventor) fiddling with the dimensions until the volume and the looks where to my liking - remember to take the internal bracing into account if you are going this route.
    The lower left pics shows Matts design volumes in Liters (without the braces) and my final "boring but makeable" designo_O. I also made a model of the volume finale design - The top/upper chamber is not used for anything but is a consequence of having make a complete box. Hope this makes sense. in the bottom there is a small chamber which can be avoided - I chose this to get a nice dimension on the front baffle (its 1200mm). Some of the measurements have to be tweaked a little when converted from inch to mm.
    Internal Volumen.jpg

    An easy way of finding the volume of the bracing is to draw them all as one piece and letting your CAD program tell you the total volume of your bracing - very easy and fast and most important!! No energy spend on doing math :D No calculators where hurt during this design:p:p:p
    Screen Shot 12-14-18 at 08.18 PM.JPG

    I used the same method for the CENTER and the TM's. My center design is longer than Matt's original but has the same volume - but I might change the center design - i'm not sure

    I'm planing to share my build here, when I start cutting the MDF:D


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