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. Unfortunately I don't have the cabinet 3d models with metric units.

    I do have metric dimensions for the MTMWW tower posted here if it helps at all.

    Edit: realized I can just switch to metric values in sketchup, here is the Center cabinet, you can round everything hole numbers without issue:
    Center cabint metric.png


    The driver models and crossover components needed are posted in the BOM images in the posts for the respective designs. You don't have to use Dayton crossover parts, you can substitute similar parts from other available brands you can get easier in Sweeden as long as the values are within +-10%, the voltage rating on the capacitors does not need to match, just needs to be equal or greater. The Sku's listed in the BOM are for partsexpress.com, you can use those item numbers to look up the exact parts on their website if you want.

    I do not think ebay will let me mark items as gift on the customs declaration form.
     
  2. I measured the Nexus TM and MTM on the turntable today. I still have to offload the files but I'll have the detailed measurements of those two posted soon.

    The TM had an unexpected peak near 900hz and I'll post the on axis measurement showing that. I ended up doing the full set of measurement with a crossover fix for that peak.

    The fix requires a change in value to two existing parts and two new parts which will have to be mounted off the PCB if you have one but those two extra parts are wired inline with the woofer positive lead so it's very easy to implement.
     
  3. Hello again,

    almost thought the forum post was too old to get a reply :)


    was very happy for the answer, went through again and found the pictures you posted, will go through everything I printed and there will probably be more questions :)

    trying to understand English as best I can :)

    Dayton is sold in Sweden, but is twice as expensive as a judgment in the US, but there is a good German site that I can order on, you avoid customs duty within the EU ..

    I showed the construction that you did to a lot of friends, and they became very interested, one of them asked if you can build the speaker that is drawn in the picture? gets more volume unfortunately, have no idea if the speakers react to it, saw that there were sawn holes in the inner shelves up to the last chamber, so that was why I ask if it is possible to build like that without losing anything, maybe have to make narrower or less depth to compensate for the volume?

    thanks again for the answer, and for taking the time to change to millimeters from inches .. thank you very much ..

    many greetings from a cold and snowy Sweden :)
     

    Attached Files:

  4. Yes it's perfectly fine to build the cabinet with a straight back instead of angled at the top. There is no need to change anything else. The cabinet internal volume/airspace is only marginally larger and won't change the woofer response or cabinet tuning much at all especially if that top portion if filled with damping material.

    Example of a build like that.

    And Another.
     
  5. #205 mga2009, Nov 10, 2021
    Last edited: Nov 10, 2021
    OK, looking forward to the measurements and the XO fix to mod my speakers.

    Pierre Aubert updated his site, and here is the webpage for the Nexus Center:
    A collection of loudspeakers measurements (pierreaubert.github.io)

    According to the score, it's one hell of a speaker design.

    UPDATE: Matt, Pierre Aubert told me that if you can get the measurements per angle instead of the aggregated spinorama that would be even better, that way he can generate all the graphs.

    If the exports are coming from VituixCAD, it does it out of the box.
     
  6. mga2009 likes this.
  7. #208 Matt Grant, Nov 10, 2021
    Last edited: Nov 10, 2021
    Here is a link to the full set of Nexus MT measurements, these are taken with the new crossover modification. I've got the full polar response file link on that page.

    Here is just a quick on axis look at the difference between the stock crossover and the modified one. Note I didn't blend in a nearfield LF response of the stock design measurement which is why they look different there.
    Nexus MT LF Blend + Crossover mod vs stock.png

    I added the updated crossover info back on the original post for the MT Design.

    Edit:
    Here is a link to the full Nexus MTM Measurements as well.
     
  8. Thanks Matt.

    All the data sent to Pierre, so probably will be updated in a few days.

    There are a handful of open/free DIY designs with complete spinorama data, so this is great news.

    Do you have a DIYSG Fusion 6 TM by any chance?

    Cheers
     
  9. I do have the original Fusion-6 cabinet and drivers I could throw together but I'm unsure how many more good days to test I'll have this year if any. Just had a couple warm days here and I was able to get measurements on 8 different designs over those two good days but now there are multiple days of rain/snow mix in the forecast.

    I'm not sure if you happened to see these but I do have data for my VBS-6.2 design posted.

    As well as the HT-12+ design (upgrade crossover for HT-12 kit).

    I have measurements for the normal HT-12, HT-10, HT-8, my Argos MTM design and the old MTG-08 design (not sure that one is worth posting) I just need to blend the nearfield LF response onto the measurements for all those. I also took measurements of my AlTi design as well but I'm making some adjustments to the crossover based on what I measured (hump in the midrange similar to the Nexus MT) and want to listen to the changes before finalizing them.

    I'm also finishing up a VBS-10.2 design too. Budget 2-way 10" woofer with waveguide/horn loaded compression driver. Bigger brother to the VBS-6.2. I've got full measurements of that one but I still need to create the whole writeup/design page for it.

    There is a new limited edition DIYSG kit coming soon that I have full measurements of as well.

    Though I don't want to overload Pierre lol.
     
  10. WOW, that's a lot of measurements! I will be following them closely.

    If you happen to have some extra time for an extra measurement, I am signed for the Fusion 6 TM!

    Cheers
     
  11. #212 Dave, Dec 12, 2021
    Last edited: Dec 12, 2021
    Hi Matt, I'm looking to build a matched LCR soon for behind and acoustically transparent screen. The MTMWW are tempting but I don't think I can fit all of the drivers behind the screen without the tweeters being way to high. I assume the WWs need line of site to the listener as well because of the higher (450hz) cross over, and cant be blocked?

    If I am crossing over with multiple subs in the room are the MTMs the better way to go for matched LCR behind the screen?

    EDIT: OR .... could I run the TMWW or MTMWW upside down? I think i read the MTMWW crossover was designed with WW interaction with the floor....

    -Dave
     
  12. Hi Dave,

    You could use the WTMW center design and rotate the tweeter and midrange 90 degrees. You just might have to increase the length of the cabinet a little bit to fit the mid and tweeter between the woofers.

    The MTMWW tower could potentially be converted to WMTMW. I don't know exactly how that would measure in the bass range but the crossover between the woofer and midrange and everything upwards from there should be ok. If you use any room correction it should help fix any minor response irregularities below that range.

    The woofers don't need perfect line of sight, something like the frame of the screen wall if built from 2x4 shouldn't be an issue in front of them assuming the rest is acoustically transparent fabric. If it's more solid then no that would not be ideal.
     
  13. Yes! it looks like your are right, the WTMW vertical would be a better fit. I increased the size from 26" to 30" inches and modeled them with the screen (attached). I do have some more height I could use, would it make since to increase the volume and port, still leaving the drivers towards the bottom of the cabinet? or better to just leave as is at 30" sealed?
     

    Attached Files:

  14. If you are going to use subs there is no need to port as it will extend below 60hz sealed.
     
    Dave likes this.
  15. Thanks, Matt. that is my plan.

    After research AT screen material, I am likely to build my own using Seymour Center Stage XD fabric. I'll have to do room measurements at some point to confirm but it looks to be a -2db drop starting at 2khz through 20khz.

    would adjusting R3 (4ohm) on the tweeter crossover help boost this or do you recommend relying on room EQ? I'm trying to be as efficient as I can on the amplifier and a near 3db boost hurts!
     
  16. On this design R3 by itself mainly controls output above ~5khz.

    In order to get a more linear 2dB lift above 2kHz you need to adjust C5 to 5.1uF, L5 to 0.40mH and R3 to 2 Ohm.
     
    Dave likes this.
  17. Hi Matt, stunning project!
    I'm planning to build It as my first DIY audio project.

    Just one question, Is It possibile to use the MTM layout as center channel? Or some crossover changes are needed?
    I want to start small and then maybe build the WTMW speaker
     
  18. Yes the MTM can be used as a center channel, no need for any crossover changes.

    Like most MTM designs it will have a fairly narrow horizontal dispersion when placed horizontally which can be seen on the vertical measurements. Ideally you would want to remain within +- 10-15 degrees otherwise you may begin to notice a reduction in output from the midrange due to the interference between the woofers as you move off to one side or the other. Though for non critical listening it's usually not terrible.
     
  19. Hello matt i recently stumbled onto this thread of loudspeakers and im interested in building the center as well the the front left and right (but for now just the center) i was wondering how hard would it be to replace the tweeter with a ribbon driver ?(and would that be a good idea) also hows does this speaker compare if you can compare to other projects ? (i saw a similar project the Khan series of speakers )
     
  20. The crossover is tuned for the specific sensitivity, frequency response, phase response and impedance of the drivers used. Changing a the tweeter would require all new measurements be taken and a rework of the crossover to compensate for differences in any of those variables, not a simple task.

    I can't really compare the design to the Khan speakers having never heard those. They are similar in design so I expect the main noticeable differences will be in voicing. The Khan designs do use the Dayton reference drivers so I expect their distortion performance to be slightly better but I can't say how noticeable that would be.
     
    Markos likes this.
  21. Thanks for the reply im looking at building some new speakers and im not sure what to go for tbh
     

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