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The DN-10's -- 2016 MWAF Dayton Audio Category Entry

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  • The DN-10's -- 2016 MWAF Dayton Audio Category Entry

    Here is a write up of my 2016 MWAF project entry, "The DN-10's" (Dayton Neodymium 10's)



    The DN-10's are a small, full-range tower speaker designed primarily for a medium to small space like a bedroom or modest living room.

    Design Goals:

    I wanted to design a smaller tower speaker set that could reproduce full-range sound, while still being fairly compact in size: with enough bass that a sub would not be necessary for normal music material. Building on a former design, "The Curves" I tried to create a speaker shape that would be pleasing to the eye, incorporate some interesting curves and angles, but still be fairly easy for most anyone to construct. The upward angle of the speakers helps to project the sound into the room.

    Driver Selection:

    I looked at several woofers for this design, but continued to come back to the well-known ND-105-4 woofer, as no others could reach as low in such a small box with as much excursion. Chris Roemer used this driver shortly after it became available in his "Neo Nano" and "NTN" speaker designs, which immediately became hugely popular -- and for good reason... amazing bass in a fairly small package. The ND-105 is indeed a special driver.

    The tweeter I picked for this mini-tower was the ND-28F-6, which is a 1 1/8" driver, as opposed to the smaller 3/4" domes usually paired with this woofer. I wanted to try a slightly higher-end tweeter with this and see what I could do to create a dynamic sounding tower which gave up nothing except for some efficiency and overall SPL... these are only 4" woofers after all.
    The Passive Radiator is a Dayton model SD270-PR with about 20 grams of weight added.

    Those with sharp eyes will notice that the passive radiator looks a bit different than the one that Parts Express sells... that is because the dust cap on the stock PR being smaller, made the center of the PR look very deep inside the cabinet when viewed from the side... I added a Parts Express 5" dust cap to each PR to give the appearance of the cone of the passive radiator being closer to the outside of the cabinet; this was just for aesthetic reasons of course, the PR performs perfectly without that modification.

    Enclosure Design:

    The enclosure may look complicated compared to a standard rectangular shaped box, but it's fairly easy to construct using 3/4" MDF. The front-to-bottom, and bottom-to-rear angles are standard 90 degree angles. Only the top has an angle incorporated in it, and both of those angles are the same at 84 degrees, simplifying panel cutout. The curve on the front begins under the drivers, 12" down from the top and is complete by about 4" from the bottom of the cabinet. I carefully cut out one cabinet side profile, sanded to get a perfect curve, then duplicated this 3 more times, rough-cutting a good 1/16" wide, and trimming the excess MDF with a straight cut router trimming bit to create 4 exact copies. The approximate box volume is .8 cu. ft. The system has an F3 of 41 Hz. • F6: 37 Hz. • F10 33.5 Hz.

    Enclosure Assembly:

    I assembled the top, bottom and back as one glue-up assembly for both speakers, at the same time I glued the 4 cross-braces and one horizontal brace to each of the two sides, remembering to do mirror images of the horizontal brace behind where the passive radiator would go. After all of those glue-ups had cured, I then glued on both sides in one operation.















    Gluing on the baffle is next. The three 1/4" thick oversized MDF panels that make up the baffle were sanded with a low grit to encourage good bonding of the glue. I used regular Titebond II to bond the panels to each other, then Polyurethane glue (Gorilla Glue) to bond the last panel to the speaker carcass. This was all done in one operation. Many clamps were used to keep things from sliding around too much as glue can act like a lubricant until it begins to set up. A few brads can also be used to keep things from sliding around until all can be clamped down securely. It doesn't take much pressure to hold down the three 1/4" panels, it can be done in dry-fit with my one hand fairly easily.







    After a good 24 hours remove the clamps and use the flush trim bit in the router to remove any overlap of the front baffle layers from the speaker. After some sanding and filling of 'mistakes' they are essentially 'done' except for driver recesses and cut-outs.
    I did let my cabinets sit for a few months... I like to do this whenever I plan on veneering so the end seams of the MDF don't expand in the future and swell up, causing what I call "joint creep" which can show up months later.
    I even glued a sacrificial 1/16" sheet of raw oak veneer to the top after sanding several times to prevent this from happening.







    The veneer I used was white birch. The black stripe in the middle is actually just the same white birch veneer, just stained black.







    I am not an expert when it comes to putting the final finish on completed speakers. What I've finally found that works well for me is simple Minwax wipe-on polyurethane applied with a cotton cloth -- a piece of old T-shirt works well. Sand with 320 grit sandpaper between coats to smooth the finish. 6-7 coats is enough to create a nice, even shine with a smooth feeling underhand.

    Crossover Design:

    The crossover for the DN-10's is not complicated, consisting of only two components for the woofer, and five for the tweeter including L-Pad to bring the level in line with the woofer -- seven components in all, resulting in an approximately 2,200 Hz crossover point. The woofer filter is a second-order L/R electrical, and approximately fourth-order acoustical. The tweeter filter is third order electrical with a resistor in parallel with the final cap to tilt up the dropping response of the tweeter. This is an 8 ohm speaker and likes a bit of power to perform well. However, I have powered it with the popular Lepai 2020A mini-amp and was able to achieve a fairly loud volume with it, so you don't need a high-powered amp to create good sound with these.








    Continued...
    Last edited by tomzarbo; 07-17-2016, 08:24 AM.
    *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
    *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

    *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

  • #2
    Conclusion:

    I feel like the goals I set for this project were achieved... good, clear music reproduction with a solid low end in a modest sized mini-tower format. Placing the passive radiator low to the ground helps this speaker 'couple' to the ground in the bass department, giving the low end a nice solid feel to it.

    Tips and Tricks:

    The best trick I learned and used for this project is the method of achieving the black stripe down the middle, which adds some pizzazz to a fairly basic design. I carefully cut a 1.5" wide strip from the piece of veneer I intended to use for the baffle. Rather than start at the top, I elected to begin the stripe under the tweeter, which made the process fairly easy. Once the center point of the tweeter was located on the piece of veneer, I cut the strip out of the veneer with a new utility knife blade, and a sturdy metal straight edge. I then stained those pieces with ebony stain and let them cure for a good day or so. I then taped them back into their respective pieces of raw veneer with blue painters tape. I then adhered the veneer pieces to the baffles using my preferred iron-on method. The process worked perfectly, and the resulting crisp line makes these speakers really stand out.

    Also, it's a good idea to weigh carefully the amount of weight added to the passive radiator. The Dayton passives include a machine screw and small washer to be used to hold whatever weight you intend to add. I ended up adding a few washers to achieve the weight I needed for the desired tuning. I used blue thread-locking compound on both the machine screw and also a touch between all of the washers to help lock them in place.

    Since I dislike routering out driver recesses, I used a forstner bit to make the recess for the tweeter, then I used another bit the size of the barrel for the driver cut-out. The woofers need no recess as they are surface-mount drivers.

    Also, I installed a square of 'Ultra-Touch' Denim Insulation approximately behind the two woofers; about a 8" x 10" square, just pushed into place held by friction around the horizontal braces. This is just to soften any reflections in the area behind the woofers.

    Products Used:

    Tweeter: Dayton ND28F-6 (2) Part Number 275-040
    Woofer: Dayton ND105-4 (4) Part Number 290-212
    Passive Rad: Dayton SD270-PR (2) Part Number 295-494
    Terminal Cup: (2) 260-309
    ERSE 3.5mH 18 AWG I Core Inductor (2) Part Number 266-560
    Solen 16uF 400V Polypropylene Capacitor (2) Part Number 027-578
    Dayton Audio 10uF 250V Polypropylene Capacitor (2) Part Number 027-428
    ERSE 0.27mH 18 AWG Perfect Layer Inductor Crossover Coil (2) Part Number 266-810
    Dayton Audio 6.8uF 250V Polypropylene Capacitor (2) Part Number 027-424
    Dayton Audio 2.4 Ohm 10W Precision Audio Grade Resistor (2) Part Number 004-2.4
    Dayton Audio 5.6 Ohm 10W Precision Audio Grade Resistor (2) Part Number 004-5.6
    *OPTIONAL: Parts Express 5" Poly Replacement Speaker Dust Cap (2) Part Number 260-385
    *OPTIONAL: Black Rubber Cement Speaker Repair Glue 1 oz. Bottle (1) Part Number 340-078

    I substituted several buyout components with similar values to build my crossovers, feel free to do the same where you can.

    TomZ
    Last edited by tomzarbo; 07-17-2016, 08:01 AM.
    *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
    *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

    *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

    Comment


    • #3
      Very nice write up Tom, wouldn't expect any less from you. Congratulations again on the 1st place finish! Well deserved, they sounded and look fantastic!
      My "No-Name" CC Speaker
      Kerry's "Silverbacks"
      Ben's Synchaeta's for Mom
      The Archers
      Rick's "db" Desktop CBT Arrays
      The Gandalf's

      Comment


      • #5
        Good lawd I want to build a pair....exactly the same. Wish I could have had a listen.
        Builds - C-Killa - Speedsters - LithMTM - Talking Sticks - Pocket Rockets - Khanspires - Dayton RS Center - RS225/28A - Kairos - Adelphos - SEOS TD12X - Dayton 8 - Needles - 871S - eD6c - Overnight Sensations - Tritrix (ported) - Lineup F4 - Stentorians - The Cheapies - Tub Thumpers - Barbells - Tuba HT - Numerous subwoofers - probably missing a few...... :p

        Comment


        • #6
          Good FR, Tommy!
          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*

          Photobucket pages:
          http://photobucket.com/Wolf-Speakers_and_more

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

          Comment


          • #7
            Very nice!

            Comment


            • #8
              Interesting design Tom. And well executed. I like it!
              Don't worry, if your parachute fails, you have the rest of your life to fix it.

              If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

              Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.:D

              Comment


              • #9
                Thanks for the kind words fellas'. And yes, Wolf, I'm real proud of the frequency response... A kind member of this board gave me a quite a bit of instruction on taking good measurements and getting files ready for crossover simulation; That helped immensely.

                Also, even though I used 3 layers of 1/4" MDF for the baffle. I bet one layer of 3/4" would work if the curved area were kerfed heavily about 3/8" deep or so. The bottom 4" and top 12" of the baffle have no curve to it, to make life easier. Care would need to be taken to not go too deep with the kerf cuts to avoid "Faceting" as another forum member termed it.
                I actually made a speaker similar in shape to this several years ago and I just manhandled the front 3/4" baffle into place with clamps, no kerf cuts at all. I wouldn't recommend that, though. It reminded me of Rodney Dangerfield preparing to jump off the end of a diving board. LOTS of stored energy there!

                TomZ
                *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

                *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

                Comment


                • #10
                  How did you end up with such large values for the woofer crossover? If you plug those drivers into a simple calculator to get a crossover point of 2,200 hz, you end up with some pretty small values on the coil. Is that just a large amount of bsc?
                  Eric L.

                  Comment


                  • #11
                    Originally posted by brkitup View Post
                    How did you end up with such large values for the woofer crossover? If you plug those drivers into a simple calculator to get a crossover point of 2,200 hz, you end up with some pretty small values on the coil. Is that just a large amount of bsc?
                    There is a fair amount of BSC built into these. My goal was no sub necessary; also, this was just the best way to meet my desired ends.... hey what's a few millihenries among speaker builders?

                    TomZ
                    *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                    *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

                    *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

                    Comment


                    • #12
                      Originally posted by tomzarbo View Post

                      .... hey what's a few millihenries among speaker builders?

                      TomZ
                      Especially when you have a stash like this to play with.

                      Click image for larger version

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                      My "No-Name" CC Speaker
                      Kerry's "Silverbacks"
                      Ben's Synchaeta's for Mom
                      The Archers
                      Rick's "db" Desktop CBT Arrays
                      The Gandalf's

                      Comment


                      • #13
                        Nice job Tom! I like the black stripe, cool idea. I was curious, what brand/type was the black stain you used?

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                        • #14
                          Great write-up. And I really liked the sound too! Very nice ground level picture of the finished speaker in post 1.

                          Keep up the good work!

                          Bill
                          Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                          Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build
                          Plan-Tanic: http://techtalk.parts-express.com/sh...ght=Plan-Tanic

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                          • #15
                            Originally posted by 4thtry View Post
                            Very nice ground level picture of the finished speaker in post 1.
                            Yea, it makes them look like big full size towers when in reality they are barely waist high. They still sounded plenty big!

                            My "No-Name" CC Speaker
                            Kerry's "Silverbacks"
                            Ben's Synchaeta's for Mom
                            The Archers
                            Rick's "db" Desktop CBT Arrays
                            The Gandalf's

                            Comment

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