Announcement

Collapse
No announcement yet.

The Boomsticks - a high WAF, slim tower with 4x Dayton RS100-8 and ND25FA

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • The Boomsticks - a high WAF, slim tower with 4x Dayton RS100-8 and ND25FA

    Click image for larger version

Name:	IMG_1549.jpg
Views:	1
Size:	349.9 KB
ID:	1325814

    Click image for larger version

Name:	IMG_1553.jpg
Views:	1
Size:	951.9 KB
ID:	1325815

    Click image for larger version

Name:	IMG_1557.jpg
Views:	1
Size:	338.9 KB
ID:	1325816

    Click image for larger version

Name:	IMG_1558.jpg
Views:	1
Size:	754.8 KB
ID:	1325817

    Click image for larger version

Name:	IMG_1559.jpg
Views:	1
Size:	965.5 KB
ID:	1325818





    Project Description:
    “Yeah. All right, you primitive screwheads, listen up. See this? This…is my BOOMSTICK! It’s a 4″ quad woofer tower, S-Mart’s top-of-the-line. You can find this in the electronics department. That’s right, this sweet baby was made in Ann Arbor, Michigan. Retails for about $299.95. It’s got a MDF stock, brushed aluminum and a hair trigger. That’s right. Shop Smart. Shop S-Mart. YA GOT THAT!?”


    The Boomsticks are a slim, high-WAF, tower design with surprising bass output given the small woofers and relatively diminutive footprint. They utilize the Dayton RS100-8 and Dayton ND25FA.

    Design Goals:
    I’ve always loved the look of slim “lifestyle” towers that you get in those home-theater-in-a-box (HTIB) systems, but they always perform terribly. If they even come with towers, the HTIB systems typically lack any real bass output, use cheap quality drivers, and plastic enclosures. This leads to localization issues with the sub having to be crossed too high, high, distortion, and resonant enclosures.


    I wanted to make something that had a similar look of those towers – slim and sleek with multiple drive units – but performed better in all aspects. I’ve always loved the look of multiple driver towers, and I think most people probably feel the same way about this. I also wanted this design to be good enough for both music without a sub and movies in a HT system with one.

    Driver Selection:
    For this build, I needed a small driver that could play deep in a relatively small enclosure. However, most small drivers suffer from less than stellar bass reproduction when they can reach low due to high distortion from the small cone trying to reproduce those notes. This is especially apparent as you turn up the volume. After considering a few different options, I settled on the Dayton RS100-8. I went with the 8 Ohm version over the 4 Ohm so that it would have more appeal to people building this design.


    There are a number of reasons I chose this driver. First, the outside frame is just under 4” diameter, which meant I could keep the cabinet very slim. Second, the RS100-8 already has low midrange distortion, and adding 4 per side allowed me to lower that even further, reduce the excursion demands at higher outputs, and therefore lower the bass distortion as well. Four of them per side gives you roughly the same cone area as a single 7” driver. You also end up at roughly 85dB efficiency at 1 watt and roughly 85 db sensitivity at 2.83V, which is a few dB more than most 7” drivers would be at if used in a standard 2-way. Third, they have a unique set of T/S parameters, that when vented in an oversized box, actually reduces a lot of the excursion demands on the woofer (see excursion graph), again, leading to lower distortion from the small driver.

    I knew I wanted a tweeter with a small faceplate to keep the look proportionate and the spacing on the drivers close. I ended up deciding to keep it all Dayton and go with the Dayton ND25FA. This tweeter met my requirements for a small faceplate, it can cross reasonably low, has very good distortion for its price, and a smooth response.
    -Kerry

    www.pursuitofperfectsound.com

  • #2
    Enclosure Design:
    The enclosure was designed to be tall and slim. Dimensions and driver layouts are in the cabinet drawing below. All material was 1/2" MDF. I used 3 window pane style braces in the cabinet. Location of the braces is not critical as long as they don’t interfere with the port opening or block driver cutouts. You can use more than 3 if you so desire.

    The internal volume of the enclosure came out to be right around 18-18.5L after ports, drivers, and bracing. The cabinet is tuned with two 2” diameter, 7.25” long ports. This gives a tuning around 55 Hz with an f3 around 48 Hz. This provides a fairly satisfying bottom end without the use of a sub.

    A single 2” showed vent velocity exceeding desired max at higher output levels which could lead to chuffing. A single 3” PVC looked like it might block the inside of the cabinet too much once an elbow was added for the necessary bend to cover the length.

    An access panel was cut into the bottom of the cabinet for the crossover that can reached by removing the base. The aluminum ring around the tweeter is not a necessity and leaving it off will not change the design at all. It was added because I thought I might eventually try the Morel CAT408 in these.

    Click image for larger version

Name:	Capture.PNG
Views:	2
Size:	30.3 KB
ID:	1325823


    Enclosure Assembly:
    These enclosures were CNC cut and shipped to me as a flat pack by forum member Kevin K. but can easily be cut with a table saw or track saw and a router. The only special treatment I did on these was using some Flex Seal on the inside of the cabs to try and deaden the enclosure some. In the end, I found this to likely be a waste of money given the price and the small benefit it seemed to provide in deadening. I would stick with something like flashing paper or car audio CLD material in the future. I could have covered just as much area at a higher thickness for equal or lesser price. The cabinets were then lined in the upper half with denim insulation. I used double thickness right behind the drivers.

    The paint I used on these was Dupli-Color Metalcast. After using a filler primer, I put down the Metalcast base coat, which is a light silver metallic flake. I then used a mixture of red and orange of the top coat to get the color I was wanting. I had a difficult time with the Metalcast getting it to go on evenly and it led to some uneven shading you can see in a couple of the pictures. I don’t think I would try this again on a cabinet this large, maybe on a small bookshelf though.
    Click image for larger version

Name:	03fe34eda4554b316ac6e5a60aba7313.jpg
Views:	1
Size:	398.8 KB
ID:	1325824

    Click image for larger version

Name:	e282fa4f351635334f0c4156e4e6d174.jpg
Views:	1
Size:	389.6 KB
ID:	1325825

    Last edited by Navy Guy; 03-29-2017, 12:56 PM.
    -Kerry

    www.pursuitofperfectsound.com

    Comment


    • #3
      Crossover Design:
      The crossover turned out much simpler than I had expected. The woofer section is a damped second order electrical with a bottomless notch and then an additional coil on the .5 woofers. Tweeter is second order electrical with a resistor before and after the crossover. The tweeter ended up roughly second order acoustic at 3200 and the woofers sum to around fourth order at 2700. The RS100 is a small enough driver that this leads to a fairly well controlled off-axis response. For the small capacitor across the inductor in the woofer circuit, I used a 0.1 uF and 0.22 uF capacitor in series with each other and then parallel across the inductor to get the value I needed. A 0.1 uF by itself is pretty close but not exactly where the breakup on my woofer measured.

      The design does dip to around 3.5 Ohm in the upper frequencies due to the small inductor on the tweeter circuit, but it is high in frequency and the phase angle is relatively small, so it should still be fine on most 8 Ohm amps. You can see this in the measured impedance below.
      Click image for larger version

Name:	Crossover.jpg
Views:	2
Size:	41.9 KB
ID:	1325826

      Click image for larger version

Name:	Impedance.gif
Views:	2
Size:	18.7 KB
ID:	1325827




      Measurements:
      As you can see from the measurements, these have a nice, wide dispersion pattern with well controlled off-axis performance. You can also see some nasty room modes showing up in these measurements. I still need to take a listening position measurement to see how bad it is in the place they will reside. In addition, distortion performance is very good from about 300 Hz up even at 95db (measurements taken at 30") and still respectable in the bass from such a small driver extending so low.

      Click image for larger version

Name:	image_65402.png
Views:	2
Size:	18.7 KB
ID:	1325828

      Click image for larger version

Name:	image_65403.jpg
Views:	2
Size:	60.3 KB
ID:	1325829

      Click image for larger version

Name:	image_65404.jpg
Views:	2
Size:	47.7 KB
ID:	1325830





      Last edited by Navy Guy; 03-28-2017, 08:25 AM.
      -Kerry

      www.pursuitofperfectsound.com

      Comment


      • #4
        Click image for larger version

Name:	image_65405.jpg
Views:	2
Size:	46.3 KB
ID:	1325834



        Tips & Tricks:
        Youíll need to plan out the size of your crossover board and layout carefully. Access through the driver cutouts is pretty difficult and even the bottom panel I had on mine didnít allow much space. A rear access panel might be a slightly better option. As always, I recommend buying a couple resistors of different sizes to play around with the level to taste. On the tweeter circuit, youíll want to adjust the resistor closest to the tweeter. If have the speakers pushed up against a wall or in corners and feel they are too dark, try reducing tweeter padding and if necessary, go to a slightly smaller inductor in the woofer circuit.

        Conclusion:
        This design was a fun build and provides for a what I would consider to be a pretty cool little speaker. Honestly, I expected more tradeoffs when going with this format than I had to make in the end. But looking back on how this turned out and considering if I were to build something in a 2-way with a single 7Ē woofer instead to get roughly the same cone area, my box would be wider, I would have to have a more expensive tweeter that would cross lower to maintain off-axis performance, I would have less sensitivity, I might actually have less cone control on bass heavy material, and potentially more midrange distortion. The only thing I think a 7Ē 2-way would bring over this design would be slightly lower bass distortion if I were using a higher end driver and a little bit more extension in a much bigger cabinet. But as you can see from the distortion plots, this is still a rather clean design, especially above 300 Hz.

        Below, you can see the in box response of this system at 30watts of the Boomstick (black) vs the Standards (gray). Ignore the the graph says RSS315. I didn't change the name in WBCD. For comparison, the Standards are in a 1.16 cu ft (around 32 liters) cabinet. The next two graphs are of the excursion of at 30 watts, first the Boomsticks, then the Standards. While the Standards have a bit more extension, this design is slightly more sensitive and shows better cone control below tuning.

        Click image for larger version

Name:	Comparison - Standards vs Boomsticks at 30 watts.gif
Views:	1
Size:	57.4 KB
ID:	1325876

        Click image for larger version

Name:	Boomsticks Excursion.gif
Views:	1
Size:	11.0 KB
ID:	1325877


        Click image for larger version

Name:	The Standards - Excursion.gif
Views:	1
Size:	11.8 KB
ID:	1325878



        So the real question everyone always wants to know is how do they sound? Iím very happy with them. They measure very flat and sound very neutral overall. Vocals still have a standout quality to them though. That might be due to the very low midrange and up distortion. They image very well, especially with some space between and around the speakers. Iíve also really cranked these to try and get into some excursion issues and I havenít been able to get the cones moving much at all, even at hearing damage levels. Overall, this is one of the few projects Iíve done where I felt like I not only met my initial expectations, but exceeded them. I really expected more tradeoffs when I first started planning this one out.
        Last edited by Navy Guy; 03-28-2017, 08:19 AM.
        -Kerry

        www.pursuitofperfectsound.com

        Comment


        • #5
          Really nice. I am impressed.

          Comment


          • #6
            Great project Kerry! They turned out great...look great and sounds like they are quite impressive. Followed your build from the start, really appreciate you documenting your process, choices and finishing progress. Motivates me to get off the couch and build something.
            Paul

            The "SB's" build page
            http://techtalk.parts-express.com/sh...-4-(pic-heavy)

            Comment


            • #7
              Those look awesome! I'm also a fan of narrow/deep/tall looks like that. That off axis and polar response looks incredible too, very nice work.

              Edit: Nice photos too.
              Your results may vary.

              Comment


              • #8
                I can't figure out how to do multi-quote anymore from the desktop site.

                ontariomaximus - Thanks!

                Bullit - I'm happy that PE has let us share our progress along the way now. It makes it easier for me if I can document it as I build some, rather than trying to do it all at the end.

                Matt - Thank you! My wife likes the look of these quite a bit. She doesn't really like the look of most of my others, although she'll deal with me putting them in the living room if I asked, so this helped me replace the B&W speakers. Now to find someone to sell them too ;)
                -Kerry

                www.pursuitofperfectsound.com

                Comment


                • #9
                  Awesome! The tall and slim cabinets look great and even the drivers look good together.. Sounds like a sub would allow these to effortlessly scream.

                  Comment


                  • #10
                    Kerry,

                    Those are just amazing looking speakers. All the little details like the beveled front and trim ring around the tweeter and perfect driver recesses make these really look fantastic.
                    You've managed to get some nice bass out of them as well. I remember being excited about the RS100's when they first came out and also being surprised at their bass output capabilities for such little buggers. Nice narrow profile no spouse would likely have any issues with.

                    I really love the color too. Those things are going to be pretty popular I bet!
                    Beautiful man!

                    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


                    • #11
                      Originally posted by randyohoh View Post
                      Awesome! The tall and slim cabinets look great and even the drivers look good together.. Sounds like a sub would allow these to effortlessly scream.
                      Yeah, if you cross these at 80 Hz you can put 100 watts to themand get 110 db before excursion issues. Not sure how clean it will be at that point though. You'll be touching xmax at around 100 Hz. But you won't damage anything at least.
                      -Kerry

                      www.pursuitofperfectsound.com

                      Comment


                      • #12
                        Originally posted by tomzarbo View Post
                        Kerry,

                        Those are just amazing looking speakers. All the little details like the beveled front and trim ring around the tweeter and perfect driver recesses make these really look fantastic.
                        You've managed to get some nice bass out of them as well. I remember being excited about the RS100's when they first came out and also being surprised at their bass output capabilities for such little buggers. Nice narrow profile no spouse would likely have any issues with.

                        I really love the color too. Those things are going to be pretty popular I bet!
                        Beautiful man!

                        TomZ

                        Thanks, Tom. I have to thank Kevin for some of that. I wouldn't have been able to do the trim ring without his help. Although I did find a place that I could have ordered the aluminum spacers for the stand for a few dollars a piece.
                        -Kerry

                        www.pursuitofperfectsound.com

                        Comment


                        • #13
                          Originally posted by tomzarbo View Post
                          Kerry,

                          Those are just amazing looking speakers. All the little details like the beveled front and trim ring around the tweeter and perfect driver recesses make these really look fantastic.

                          TomZ
                          Kerry originally wanted the trim ring/cup around the tweeter so he could try a different tweeter in the cabinet later. The aluminum ring and spacers compliment his finish choice very well. After reading his write up, it sounds like he's pleased with the overall sound. Maybe the tweeter and ring will stay. I also really liked his choice to paint the bases black instead of the same color as the rest of the cab, the contrast worked out great. Overall, just a very nice looking set of speakers. It was an honor to be able to help out.



                          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


                          • #14
                            Originally posted by Kevin K. View Post

                            Kerry originally wanted the trim ring/cup around the tweeter so he could try a different tweeter in the cabinet later. The aluminum ring and spacers compliment his finish choice very well. After reading his write up, it sounds like he's pleased with the overall sound. Maybe the tweeter and ring will stay. I also really liked his choice to paint the bases black instead of the same color as the rest of the cab, the contrast worked out great. Overall, just a very nice looking set of speakers. It was an honor to be able to help out.



                            Again, I really appreciate the help on this. The fit and finish would have been much worse had I cut everything myself and I'd probably still be working on them ;) I'm pretty happy with the color, but overall still a little dissapointed in the finish quality. You can really see the shading in the second picture on the far speaker.. After InDIYana, I plan to go back and and spray another coat of red to try and even it out a little more.

                            For now, the tweeter ring is staying. I don't know if I'll go back and redo anything or not. I'm pretty happy with the sound quality on these, so I might just keep them the way they are.
                            -Kerry

                            www.pursuitofperfectsound.com

                            Comment


                            • #15
                              Yeah, the matching brightwork on the tweeter trim ring and base risers just take it up quite a few notches. Well executed and not a bad angle.
                              *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

                              Working...
                              X