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New build thread using InDIYana '11 doorprize

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  • New build thread using InDIYana '11 doorprize

    I'm hoping to have these puppies ready for InDIYana '12, and I think I'm going to start a personal tradition of using whatever doorprize I win one year in a build that I bring the next year. So what did I win?...

    A pair of Audax TW025A0s, which I've heard sound very nice, but I haven't auditioned them yet. They'll make up the top end of a super-slim TMWW with the Fountek FR88EX in the middle and a pair of ND105-4s on the bottom.

    The woofers will be housed in about 18L tuned to 40Hz in a box that is 39"h x 5"w x 6"d (ID) with a 9" tall mid enclosure on top of that. Unless someone has a recommendation on port placement to deal with quarter-wave issues, my plan was to put both woofers as high as possible in the bass section of the cabinet with the port a couple inches underneath them and then heavily stuff the bottom half of the box to beat down the pipe resonance.

    Overall dimensions will be 49"h x 6"w x 7.25"d with a 3/4" solid wood baffle. I'd really like to do walnut, but that's going to take a trip to the sawmill and I've already got some oak in the garage. We'll see how much time I can find between now and April 13th.

    I used rabbet joints on this build for the first time ever and the added time was well worth the reduced stress when it came time to assemble the pieces. I will definitely be using this strategy on future builds. I've attached a few pics of my progress so far as well as the simulation in its current iteration. The mid was quite easy to deal with but the tweeter has some weird FR stuff going on with it and the woofers impedence peaks needed to be beat down before the LP would work, so this is not a low-part-count crossover. I think I'm at 15 components right now, but I'll try to knock that down a little during voicing with real in-box measurements. 3-ways suck.

    I'm taking suggestions on EASY finishes for the sides, back, top and bottom. I don't have the patience nor the time for 10 coats of paint with 72 hours of drying and 2 hours of sanding in between.

    Dan
    Attached Files
    _____________________________
    Tall Boys
    NRNP Computer Sub
    The Boxers
    The Hurricanes
    The Baronettes
    Conneccentric
    UX3

  • #2
    Re: New build thread using InDIYana '11 doorprize

    Originally posted by DanP View Post
    I'm hoping to have these puppies ready for InDIYana '12, and I think I'm going to start a personal tradition of using whatever doorprize I win one year in a build that I bring the next year. So what did I win?...

    A pair of Audax TW025A0s, which I've heard sound very nice, but I haven't auditioned them yet. They'll make up the top end of a super-slim TMWW with the Fountek FR88EX in the middle and a pair of ND105-4s on the bottom.

    The woofers will be housed in about 18L tuned to 40Hz in a box that is 39"h x 5"w x 6"d (ID) with a 9" tall mid enclosure on top of that. Unless someone has a recommendation on port placement to deal with quarter-wave issues, my plan was to put both woofers as high as possible in the bass section of the cabinet with the port a couple inches underneath them and then heavily stuff the bottom half of the box to beat down the pipe resonance.

    Overall dimensions will be 49"h x 6"w x 7.25"d with a 3/4" solid wood baffle. I'd really like to do walnut, but that's going to take a trip to the saw mill and I've already go some oak in the garage. We'll see how much time I can find between now and April 13th.

    I used rabbet joints on this build for the first time ever and the added time was well worth the reduced stress when it came time to assemble the pieces. I will definitely be using this strategy on future builds. I've attached a few pics of my progress so far as well as the simulation in its current iteration. The mid was quite easy to deal with but the tweeter has some weird FR stuff going on with it and the woofers impedence peaks needed to be beat down before the LP would work, so this is not a low-part-count crossover. I think I'm at 15 components right now, but I'll try to knock that down a little during voicing with real in-box measurements. 3-ways suck.

    I'm taking suggestions on EASY finishes for the sides, back, top and bottom. I don't have the patience nor the time for 10 coats of paint with 72 hours of drying and 2 hours of sanding in between.

    Dan
    Get some spray sanding primer to put down a reasonably smooth surface and sand it lightly. Then spray a base coat of your color, followed by a textured paint. If you get one with speckles and don't want them, just paint one last coat of the base color, and then clear over that to keep it from gathering dust as easily. Hides the seams reasonably well without too much time involved.

    And of course, there's always Formica.
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


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    Comment


    • #3
      Re: New build thread using InDIYana '11 doorprize

      I'm glad I'll get to hear those! I think you chose drivers very well. Is the tweeter physically larger than the mid? Just curious.

      Can't wait to hear these!

      As to easy finishes- you could dye a can of polyurethane, and just give it some coats. That would be really easy. KoolAid may work.

      Later,
      Wolf
      "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
      "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
      "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
      "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

      *InDIYana event website*

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      My blog/writeups/thoughts here at PE:
      http://techtalk.parts-express.com/blog.php?u=4102

      Comment


      • #4
        Re: New build thread using InDIYana '11 doorprize

        Yeah, the tweeter is 100mm and the mid is about 90mm I think. Both of those finishing ideas sound reasonable, but the dyed polyurethane sounds stupid easy, so that's prolly what I'll do. I've got high hopes for these as well.

        Dan
        _____________________________
        Tall Boys
        NRNP Computer Sub
        The Boxers
        The Hurricanes
        The Baronettes
        Conneccentric
        UX3

        Comment


        • #5
          Re: New build thread using InDIYana '11 doorprize

          Heheh cool... I like off-beat designs and this one looks neat! Great tweeter by the way!
          .

          Comment


          • #6
            Re: New build thread using InDIYana '11 doorprize

            Four more weekends until InDIYana! I've been sneaking out to the garage when I can trying to finish these up before the get together. At this point I've got all the mounting blocks in place and all four removable baffles trimmed and mounted. I found these composite deck screws at HD that look really tidy on the baffle. No dealing with inserts and I didn't even recess the heads, so using them saved a lot of time.

            Dan
            Attached Files
            _____________________________
            Tall Boys
            NRNP Computer Sub
            The Boxers
            The Hurricanes
            The Baronettes
            Conneccentric
            UX3

            Comment


            • #7
              Re: New build thread using InDIYana '11 doorprize

              Originally posted by DanP View Post

              The woofers will be housed in about 18L tuned to 40Hz in a box that is 39"h x 5"w x 6"d (ID) with a 9" tall mid enclosure on top of that. Unless someone has a recommendation on port placement to deal with quarter-wave issues, my plan was to put both woofers as high as possible in the bass section of the cabinet with the port a couple inches underneath them and then heavily stuff the bottom half of the box to beat down the pipe resonance.


              Dan
              This plan of action is probably not going to yield optimum response, but since it's a 3 way, if the xo point is low enough it might not matter much.

              Without a simulation, I'd suggest putting the port as far as possible on the opposite end of the box that the drivers are on - in other words as close as possible to the bottom.

              I just saw this now and it's probably finished by now, but if not I can probably do a quick simulation of the bass section for you. I'd need all the t/s parameters including Bl and Sd as well as the port info (diameter, length and preferred location if any).
              Don't even try
              to sort out the lies
              it's worse to try to understand.

              Comment


              • #8
                Re: New build thread using InDIYana '11 doorprize

                Originally posted by diy speaker guy View Post
                This plan of action is probably not going to yield optimum response, but since it's a 3 way, if the xo point is low enough it might not matter much.

                Without a simulation, I'd suggest putting the port as far as possible on the opposite end of the box that the drivers are on - in other words as close as possible to the bottom.

                I just saw this now and it's probably finished by now, but if not I can probably do a quick simulation of the bass section for you. I'd need all the t/s parameters including Bl and Sd as well as the port info (diameter, length and preferred location if any).
                Just in time diy_speaker_guy. Even though the weather in Michigan has been beautiful lately, I still haven't managed to cut any holes yet, and I would love you to model this for me.

                Here's the specs according to the manufacturer (Dayton ND105-4):

                Re 3.7 ohms
                Le 0.78 mH
                Fs 53.8 Hz
                Qms 7.16
                Qes 0.59
                Qts 0.55
                Mms 7.2 g
                Cms 1.2 mm/N
                Sd 51.5 cm^2
                Vd 20.6 cm^3
                BL 3.9 Tm
                Vas 4.5 L

                Internal dimensions of the enclosure are 5"W x 6"D x 39"H with a 2"ID x 5"L port. Woofer 1 will be located at 36.5" from the bottom and woofer 2 at 32".

                My current plan is to put the port at about 26", but like I said, that's only so I can fill the bottom with enough stuffing to kill the pipe resonance. I'd much rather use that resonance if possible. Thanks!

                Dan
                _____________________________
                Tall Boys
                NRNP Computer Sub
                The Boxers
                The Hurricanes
                The Baronettes
                Conneccentric
                UX3

                Comment


                • #9
                  Re: New build thread using InDIYana '11 doorprize

                  Look up Chris Roemer. He has modeled these drivers to death and has hands-on T/S numbers on them.
                  https://www.facebook.com/Mosaic-Audi...7373763888294/

                  Comment


                  • #10
                    Re: New build thread using InDIYana '11 doorprize

                    Drivers are in series.

                    Both of the following simulations use .5 ohm resistance in series with the driver to account for amp and cable resistance as well as an added passive series crossover inductor. Depending on the components you use your actual series resistance will vary.

                    The first picture shows your original plan. Since you wanted drivers in the top and stuffing in the bottom I had to model it upside down. I included all user inputs so you can verify they are correct. It's only shown with .25lb/ft stuffing, more stuffing would smooth it out more but it's not an optimal situation. Shown at xmax (I think) - I'll talk about this more later.



                    The next pic is the changes I mentioned, keeping the woofers and the port far away from each other. I modeled this one right side up, since the stuffing is at the top. Also shown with .25 lb/ft stuffing in the first half of the line. This looks a bit better.

                    The port is down 36 inches from the top (internally) with the drivers and stuffing up in the top half of the line.

                    The first graph in this pic is frequency response at xmax, 12 watts. You didn't give an xmax spec but IIRC it's 4mm.

                    The second graph shows excursion (xmax rms = 4mm x .707 = 2.8mm)

                    The third graph shows port velocity at xmax. For reference, the top line in this graph, 0.064, is equal to about 22 m/s. 0.03 is about 10 m/s.

                    Lots of people say this driver sounds good well beyond xmax though. If you push it much past 12 watts as shown the port noise is going to be a serious problem. A larger port diameter or a lower tuning (longer port of the same diameter) would help but unless you want to retrofit a folded slot port there's not much you can do about it now inside the confines of the woofer box though. A flared port would help in theory, but since a flared port needs to be longer for the same tuning and there's nowhere to put the extra length you can't do that either.

                    One final note - your port is 5 inches long and the internal depth of the enclosure is 6 inches. That doesn't leave much room for the internal end of the port to "breathe" unless your baffle is very thick. If you restrict the airflow too much around the port it will lead to even more port noise.

                    The port diameter is going to limit the performance potential of these speakers (if the nd105 indeed sound good well past xmax).

                    Don't even try
                    to sort out the lies
                    it's worse to try to understand.

                    Comment


                    • #11
                      Re: New build thread using InDIYana '11 doorprize

                      Very cool, diy - thanks for the model. There doesn't seem to be any downside to putting the port at the bottom and you've certainly shown a downside to putting it at the top, so bottom it is. Now I wish I had cut the baffles so the bottom one could accommodate the port. That way I could spin it upside down and listen both ways to see how much of a difference there is.

                      The only thing that seems a little odd to me is that 0.25lb/cu ft in the top half of the line only turns out to be a little over an ounce of stuffing - is that really all that is recommended or should I try different amounts? Should I try to taper the stuffing gradually from woofers to port? It wouldnt be hard as there are 4 "sections" separated by window braces.

                      I'm aware the port is a little too small and a little too close to the back wall, but in my experience, it will only make an audible difference on a handful of songs, which is an acceptable compromise to me.

                      Dan
                      _____________________________
                      Tall Boys
                      NRNP Computer Sub
                      The Boxers
                      The Hurricanes
                      The Baronettes
                      Conneccentric
                      UX3

                      Comment


                      • #12
                        Re: New build thread using InDIYana '11 doorprize

                        You can use as much stuffing as you want (need). I show stuffing at .25ft/lb because that's how I model it. I get the response as it's flat as it's going to be with just enough stuffing to knock down the worst of the mess, and only then add more stuffing.

                        More stuffing will really smooth out the responses I've shown in both simulations. You can use as much as 1lb/ft in the first half of the line. Keep the stuffing away from the bottom of the box/port area.

                        If you want I can try to optomize the port location for smoothest response, I haven't bothered yet. The drivers are not necessarily in the optimal location within their enclosure either, but overall it's certainly not bad the way it is in the second simulation. Improving it is possible but it's nitpicking.

                        I can show you what it looks like with any amount of stuffing you like. Let me know.
                        Don't even try
                        to sort out the lies
                        it's worse to try to understand.

                        Comment


                        • #13
                          Re: New build thread using InDIYana '11 doorprize

                          This is the same thing as the second simulation but with .75lb/ft.

                          Don't even try
                          to sort out the lies
                          it's worse to try to understand.

                          Comment


                          • #14
                            Re: New build thread using InDIYana '11 doorprize

                            One more pic. This shows the port 26 inches down from the top (not to be confused with what I modeled in the first simulation, which was 26 inches from the bottom). The first graph is with .25lb/ft stuffing, the second is with .75lb/ft.

                            Basically you can put the port anywhere you want from 26 inches (from the top) down to the bottom. You can pick either of the locations I've shown or if you need to you can pick a new location within the specified range without harming the response too much.

                            I could probably get it flatter but I'd have to change the driver position and there's probably not much point anyway.

                            Don't even try
                            to sort out the lies
                            it's worse to try to understand.

                            Comment


                            • #15
                              Re: New build thread using InDIYana '11 doorprize

                              Which version of Martin's software are you using? If it's 2_09_08 or later, you can change the scaling of the axes in the graphs for better resolution. I particularly like to do that for the Y-axis to show F3 better as well as the response ripples. Just thought I'd ask in case you didn't know.
                              Paul

                              Originally posted by diy speaker guy View Post
                              One more pic. This shows the port 26 inches down from the top (not to be confused with what I modeled in the first simulation, which was 26 inches from the bottom). The first graph is with .25lb/ft stuffing, the second is with .75lb/ft.

                              Basically you can put the port anywhere you want from 26 inches (from the top) down to the bottom. You can pick either of the locations I've shown or if you need to you can pick a new location within the specified range without harming the response too much.

                              I could probably get it flatter but I'd have to change the driver position and there's probably not much point anyway.

                              Comment

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