Little Miss NatP version - SB15CAC-8 + Seas DXT underway

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  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 16053

    #1

    Little Miss NatP version - SB15CAC-8 + Seas DXT underway

    Well, this is inspired by Letiennam's two way in an existing cabinet, using the SB15CAC-4- I have a passle of the SB15CAD-8, and some Seas DXT tweeters, and some measurements and crossover ideas for the latter, and a whole mess of the SB15SFCR passive radiators (about 8) so I figured all I would need to for an "official" design study is an enclosure plan, and since I'm pressed for time these days, and it's juste a DESIGN Study, why I turned to those fine folks at PE because they finally have a 15L test enclosure in stock in my preferred form factor - about 8-1/2" wide, as was used for early tests of the PT5010. So I ordered 4 of the this morning, figuring I can create an unholy marriage of two of them into one cabinet, with my own custom front panel, and save quite a bit of time.

    And I even have an LR3 high pass network design that is fairly close to being in the ball park we need for an MTM, so it's "building on existing technology".



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    Note, I did not say LOW COMPONENT COUNT technology! But, rather, performance and precision oriented. Complete with HF breakup mode suppression, of course.

    A reminder: raw QNF response of the DXT:

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    This is what I call a DXT normalization network, to show what is possible with this tweeter to take advantage of it's strong points - dispersion and distortion:


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    Distortion measurements suggest a crossover in the range of 2500Hz.


    So, though there can be many a slip twixt the cup and the lip, I think pursuing this further is a reasonable endeavor. Not quite budget oriented, but a lot more so than many recent project efforts (on my part).

    And a reminder of what we're looking at to work with using the SB15CAC30-8...

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    In an MTM, the net half plane sensitivity will be pushed up 6 dB, to about 91-92 dB. Final system sensitivity with baffle step should be reasonable, with a slight downward tilt planned, given the expected wide polar response.
    the AudioWorx
    Natalie P
    M8ta
    Modula Neo DCC
    Modula MT XE
    Modula Xtreme
    Isiris
    Wavecor Ardent

    SMJ
    Minerva Monitor
    Calliope
    Ardent D

    In Development...
    Isiris Mk II updates- in final test stage!
    Obi-Wan
    Saint-Saëns Symphonique/AKA SMJ-40
    Modula PWB
    Calliope CC Supreme
    Natalie P Ultra
    Natalie P Supreme
    Janus BP1 Sub


    Resistance is not futile, it is Volts divided by Amperes...
    Just ask Mr. Ohm....
  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 16053

    #2
    And just to point out that this topic starting isn't all hat and no cattle, I should mention that 4 test enclosures have been ordered form PE that would facilitate building a pair of MTM test cabinets, and with some diligent searching, I found one more of that cabinet type on hand in the AudioWorx West warehouse. And THAT one is nearly completely assembled now, going to route the front panel and add an input panel on the back this weekend. This, of course, is to get my own data on the SB15CAC30-8, which I probably SHOULD have done before ordering the knockdown cabinet kits from PE!
    the AudioWorx
    Natalie P
    M8ta
    Modula Neo DCC
    Modula MT XE
    Modula Xtreme
    Isiris
    Wavecor Ardent

    SMJ
    Minerva Monitor
    Calliope
    Ardent D

    In Development...
    Isiris Mk II updates- in final test stage!
    Obi-Wan
    Saint-Saëns Symphonique/AKA SMJ-40
    Modula PWB
    Calliope CC Supreme
    Natalie P Ultra
    Natalie P Supreme
    Janus BP1 Sub


    Resistance is not futile, it is Volts divided by Amperes...
    Just ask Mr. Ohm....

    Comment

    • JonMarsh
      Mad Max Moderator
      • Aug 2000
      • 16053

      #3
      well, another day, a slight shift in how to get some initial data... just happens I have a nice 5.5" MT cabinet built for testing the mid+tweeter for the Kii inspired project, so I checked if it would work for the SB15CAC30-8, and boy, sometimes (not often!) I get lucky...


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      I plan to setup a "permanent" Mac on the Fuzzmeausre test cart today, so data tomorrow is a good possibility.

      I think I
      should be able to get some decent QNF data, and also 1m, and level check in comparison to the DXT tweeter.


      the AudioWorx
      Natalie P
      M8ta
      Modula Neo DCC
      Modula MT XE
      Modula Xtreme
      Isiris
      Wavecor Ardent

      SMJ
      Minerva Monitor
      Calliope
      Ardent D

      In Development...
      Isiris Mk II updates- in final test stage!
      Obi-Wan
      Saint-Saëns Symphonique/AKA SMJ-40
      Modula PWB
      Calliope CC Supreme
      Natalie P Ultra
      Natalie P Supreme
      Janus BP1 Sub


      Resistance is not futile, it is Volts divided by Amperes...
      Just ask Mr. Ohm....

      Comment


      • tradelectra
        tradelectra commented
        Editing a comment
        Hello My question is what do you put inside the wooden box is it kind of wool?
    • letiennam
      Member
      • Mar 2016
      • 55

      #4
      The progress is so fast, I really can't keep up. My friend owns sb15cac-8 and sb26cdc. I also told him about NatP for sb15cac :v

      Comment

      • JonMarsh
        Mad Max Moderator
        • Aug 2000
        • 16053

        #5
        well, there have been many tasks to track and tackle this week- this morning I installed the Mac Studio Max as the test computer on the FuzzMeasure cart, and took QNF measurements of the SB15CAC30-8 and the DXT, which I already have- that was more for level correlation.

        The result is interesting; in this case, for this enclosure and damping, the results are quite nice, and even suggest it would have very good application in an Ardent style system as the midrange- need to update that thread, too!

        But very smooth overall, up to 5kHz, and good distortion numbers for a driver of this size - about -60 dB from 200Hz up to 800Hz, then dropping to about -70 dB up to 3kHz and beyond- a simple notch filter should take care of the resonance amplification of distortion products from the upper cone breakup mode.



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        the AudioWorx
        Natalie P
        M8ta
        Modula Neo DCC
        Modula MT XE
        Modula Xtreme
        Isiris
        Wavecor Ardent

        SMJ
        Minerva Monitor
        Calliope
        Ardent D

        In Development...
        Isiris Mk II updates- in final test stage!
        Obi-Wan
        Saint-Saëns Symphonique/AKA SMJ-40
        Modula PWB
        Calliope CC Supreme
        Natalie P Ultra
        Natalie P Supreme
        Janus BP1 Sub


        Resistance is not futile, it is Volts divided by Amperes...
        Just ask Mr. Ohm....

        Comment

        • peterpan
          Member
          • May 2004
          • 37

          #6
          I wish this design will be finalised. I am on retirement and want to build this John Mash design as my last DIY Speaker.

          Comment

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