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. Thanks for those charts!

    If anyone is interested, I have made same Sketchup designs for the Nexus WTMW Center, WTMW L&R and the TM On Wall/Atmos. If Matt it's OK with it, I can leave the links here so that anyone can use them and make any modifications if needed.

    I am building my wtmw center (I already contacted you for the PCB) and converting my TM to TM Atmos.OW.JPGwtmw center.JPG
    wtmw lr.JPG
     

    Attached Files:

  2. Is there a TM Atmos design available?
     
  3. If you want to make one really compact for atmos use you could build it at the same 7" x 10" baffle size but make it sealed and only 5" deep. This will give ~100hz extension. You could also stick one of these ports in cut to about 5" long, it will have to go in the top/bottom or sides. That will tune it to around 65-70hz and give an f3 around 75hz which should make an 80hz crossover usable.
     
  4. The Nexus TM shallow design I made is tuned around 65hz (3,9 liters internal volume) and it's (W)178mm x (H) 320mm x (D) 125mm... maybe I can make it sealed and a little shorter, but thought to keep it with a tuning as close as possible to the original design. Do you see and inconvenient with it?
     
  5. Your design will certainly work well.

    I just figured keeping size to a minimum would be one of the main goals for an atmos speaker which is what I did for the above cabinet recommendation. It's pretty much the smallest cabinet I'd use that woofer in.
     
  6. Sounds good. Should I be concerned with the BSC mounting them directly to the ceiling?
     
  7. If you are using some kind or room correction in your AVR it's not worth worrying about as that should help fix any issues that arise there.
     
  8. If anyone was interested in the PCBs for these I did get more made up for both the MT/MTM and the Center/Tower designs.

    I also had some PCB made up for the Argos and AlTi designs. Once I have some photos and make up instructions for those boards I'll put them up on eBay along with the Nexus PCBs for ease of purchase.
     
  9. Please let us know when the Argos PCB are available, I'll buy 2. I'm going to see about digging out an old breadboard and prototyping the crossover and wiring it to the speakers.
     
  10. #160 Matt Grant, Mar 14, 2020
    Last edited: Mar 14, 2020
    Steve Chan likes this.
  11. #161 mga2009, Apr 1, 2020 at 7:51 PM
    Last edited: Apr 2, 2020 at 11:06 AM
    Matt,

    One quick question. In the Nexus Center, the tweeter has a 4ohm resistor. I want to use a better quality resistor there, meaning Mills or Jantzen.

    The problem is that PE, now, does not carry an exact 4ohm for those brands... If i preffer a "hotter" high frequency, better than a more "laid back" sound, should I go with a 3.9ohm or a 4.5ohm?

    Thanks in advance!

    UPDATE: I tried XSIM with the FRD and ZMA files from PE for the ND28F-6 and reproduced the XO only in the tweeter part, and tried changing the resistor value from 4ohm to 3.9ohm and 4.5ohm. It seems that a lower resistor value (3.9ohm) will produce a "hotter" high frequency response. Is this correct?
     
  12. Yes, that resistor is in series and therefor a lower value will result in more output from the tweeter. That said 3.9 Ohms will be almost indistinguishable from 4 Ohms, something around 3 ohms could be used which would be about 1dB of additional output above 5k. Changing the 4.3uF cap to 4.7uF would extend that to 2k and up.
     

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