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. I have some questions regarding the differences between a center speaker built as WTMW and possibly WTMMW as pictured in post #59 on page 3 of this thread. In post #60 it is stated:

    So, I have a few questions about this.

    First, could the circuits from the WTMW center and the MTMWW right/left crossovers be mixed for a WTMMW center? As in, could the LF (and possibly HF) from the WTMW and/or the MF & HF from the MTMWW be used to at least overcome the suspected lump in the woofer response, or would this just cause other problems?

    Would the benefits of a second midrange speaker be worth the drawbacks of the different positions of the MF/HF speakers, with or without mixing the crossover circuits?

    Lastly, can the box be built with greater length and shallower depth? Due to space considerations, I would like to keep the speakers tightly spaced in the center of the box, without changing the inner M/T box size, while extending the length of the front baffle, cutting down the depth of the box, and possibly using some angles on right and left ends of the back of the box. Assuming the internal volumes don't change much would there be any reasons why I shouldn't do this?

    Thank you very much for your time, not only with these questions but also with the designs themselves. I am just starting my journey into this hobbly and your efforts are greatly appreciated.
  2. If you are using any kind of modern AVR with room correction or even basic EQ I'd suggest building the WMTMW center if you are set on that design and using the crossover from the tower MTMWW. I don't think it's worth trying to combine sections from the WTMW center crossover. If you build it and have a mic to take response measurements I can give input on what parts to change if the frequency response is not already usable.

    There may be slight changes in the response from the individual drivers from changing the enclosure design and driver layout in the baffle but things shouldn't be terrible. Obviously I don't know the exact extent of the changes they could be minimal or change the response quite a bit. The second midrange does reduce distortion and compression as each driver only requires 1/4 the power of a single midrange.

    The enclosure could certainly be built wider and shallower if needed, minimal impact to the response and only that of the woofers.
  3. Thank you very much for your response. I do have a mic but I am only just learning how to use it, starting with a whole lot of room sweeps and fiddling around with REW and subwoofer settings. I will be moving on to building this center channel once I finish the current subwoofer project. I would like to believe that will be soon but, in the real world, I have limited time for these projects and they always take longer than I think they should. In the meantime, I will probably be reading as much as I can about crossovers, XSim, and whatever sidetracks come along.

    I'll post back here when I am making progress.

    Thanks again, for the project and the input. I really appreciate it.
  4. I apologize if this has been asked, but how would these compare to the 1099s?

    My use is 50/50 music which I usually have both cranked up pretty high (reference).
  5. Hi,

    Here is a pic of my Nexus Center shaping up. Still very rough, but looking forward to hear it!

    Attached Files:

    RSchirtzinger likes this.
  6. How are they for HT application people who have built them? Considering MTMWW fronts WTMW center MTM Rears and TM rear backs. Listen at reference on AVR.
  7. Reference will be pushing it with these on AVR power unless you have a small room.

    Reference level requires that each speaker be capable of producing 105dB peaks at the MLP. With AVR power (lets me be conservative and say 100w/channel at 8 ohms) the MTMWW towers will do 109dB at 1m. With the loss of SPL due to distance you can only get to ~5-7 feet away before they will no longer hit that 105dB peak with 100w input. What will likely happen at further distances is the dynamics in the track will end up being clipped by the amplifier when trying to listen at reference level. Even at 200w a channel you can only get ~7.5-10 feet away before they will not longer produce reference level.
  8. Hello, Matt.
    First post here, and I have lurked for a while now. I recently purchased the boards for this project from you, and all of the speakers have been received off back order. I am excited to get these cranking!
    That said, back in post 50 you gave an alternative sealed volume for the woofers. I would like to make the towers near the same depth as the center channel. What would be the detriment of doing this? I am crossing over to a pair of 15" HFs running in stereo as well. Would this make them a "mid bass" punch type of set up- essentially a 4 way?
    Thanks for any advice.
  9. You can make the tower enclosures sealed but you do give up quite a bit of output and extension at the low frequencies.

    Alternatively you could leave them ported just shrink the depth of the enclosure and the port by ~2.5-3". This will reduce extension but push the response to be a little more elevated in the midbass/kick drum range.
  10. I like that idea. I really didn't want to have to go sealed, but had a little bit of a constraint.
    Thanks much for your quick response!
  11. Matt,

    I will build 2 new Nexus TM, but I want to use passive radiators.

    Do you think using only 1 Dayton DS135-PR per speaker is enough?

    PR's xmax is not double of driver per se, but it's almost there. I am thinking an internal net volume of 4 to 5 liters.
  12. That enclosure volume works well with the single PR without needing extra mass.
    You are however limited to about 20w if used fullrange before hitting the xmax on the passive radiator, though if used with a high pass of 60hz it's not an issue until you get above 70w input (and only around 50hz).
  13. Hi Matt,
    I'm looking forward to build this speaker.
    There are few questions.

    1. Can I place the port at front at the same height from the floor?
    2. Can the cabinet be tried with curved walls, if possible?

  14. Yes to both. The port can be placed on the front or the back without issue. No trouble from curved sides either as long as you keep the baffle width close to its original size.
    Thirumal Kumaran likes this.
  15. Hi Matt,
    Excited to build these as my first DIY LCR build, not my first build, but will be the biggest and most complicated. I will be building these as LCR towers in the WMTMW configuration with the cabinet and port shrunk a bit in depth/length as you mentioned above, ports would be to the front. My set up will have these mounted behind an AT screen in my baffle wall which is 20" off the main wall. Not sure how these would work as an "in wall" speaker so to speak with wood/gyp wall finishing out around them? Do you feel it would mess with the baffle step?

    Any tips for the build or for this arrangement would be most appreciated,

  16. It will mess with the baffle step a little bit yes, but if you are using these for a home theater and will be using some kind of room correction/auto EQ in the AVR/processor it will help tame any abnormalities created by that kind of installation.
  17. Yup dedicated theater and running Anthem ARC so I will run with it.

    Thanks again,
  18. Matt,

    I noticed in other forums that you are taking measurements with a motoroized turntable providing spinorama and directivity data.

    Is there any chance you you update the measurement data on the Nexus lineup? I am mostly interested in the Nexus Center (which I am planning on using vertically as left and right) and the Nexus TM.

    Thanks in advance!
  19. #194 Matt Grant, Nov 6, 2021
    Last edited: Nov 11, 2021
    I managed to get measurements for the Nexus Center today as I was going to be taking measurements on some other speakers. I didn't get a chance to do the TM, I'll try to do that on in the next couple days.

    I still need to copy over the measurement files from my other PC but I might have the Center channel data posted tonight.

    Edit here they are:

    Measurements performed at 2.83v/2m and scaled 6dB to approximate 1m/1w output level. 14ms gate so resolution below 200hz is poor, the dip near 150hz is an artifact of the measurement style/rig as it has shown up in everything I've measured so far, I'll try to get a nearfield measurement to splice in for on the axis response for more a more accurate look at low frequencies (<200hz).

    On axis + 10 degrees off axis; when directly on axis there is a bit of diffraction ripple that smooths out as you move slightly off axis:
    Nexus Center SPL On axis + 10 degrees off.png

    CTA-2034 Spin:
    Nexus Center Power+DI.png

    Horizontal off axis:
    Nexus Center Directivity (hor).png

    Horizontal Polar (Normalized):
    Nexus Center Directivity (hor) Polar Norm.png

    Vertical above axis:
    Nexus Center Directivity (ver, pos front).png

    Vertical below axis:
    Nexus Center Directivity (ver, neg front).png

    Vertical Polar Normalized:
    Nexus Center Directivity (ver) Polar Norm.png

    An expanded set of measurements can be found here
  20. A W E S O M E.


    Looking forward to the rest of the lineup!
  21. Matt,

    Can you share the full spinorama data (in a zip file), so we can calculate the preference score and add to Pierre Aubert spinorama database?

  22. #197 Matt Grant, Nov 7, 2021
    Last edited: Nov 7, 2021
    mga2009 likes this.
  23. Matt,

    OK, great. I will wait for the spliced data to send it.

    Obviously you already know this, but Pierre prefers raw data in TXT format. (output from Vituix is ok).

    Thanks gain for this and all you support to the DIY audio community
  24. Hello

    is new to this forum, have been looking for DIY speakers build for a long time, my English is not so good, gets easily messy for me with this topic,

    I live in Sweden,
    tonight I found this thread with absolutely fantastic speakers, have read through the thread a few times to understand better,

    have some questions, I would like to build these tower and center speakers.
    but is a bit of a problem when we use mm millimeters here, are there any documents on drawings to take part of? as well as what drivers and crossover parts I need .. I am also considering buying pcb cards on ebay, but saw that it was from the US, is there a possibility to write that it is a gift? so you hopefully avoid customs duty. I hope you understand my bad English ..

    very grateful for the help ..

    again, very nice speakers .. I got hooked on them right away.

    uses me a Denon reciever from 2018 ..
  25. Thank you very much.

    Already sent them to Pierre, so probably updated in a few days.


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