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The Quarks - M.O.S.D. Computer Speaker

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  • The Quarks - M.O.S.D. Computer Speaker

    Introducing the Quarks
    A Microcosm of Speaker Design

    A micro desktop computer speaker
    by Jeff Bagby


    For years I have been using the cheap little plastic speakers that come with my computer, mostly because I really don’t have the desktop space for speakers like Continuums or Piccolos to sit there. Recently after transferring a couple hundred CD’s to the hard drive I decided to make something a bit nicer to sit on my desk. Since I am only 18” away they really don’t need to be real big and powerful, but I at least wanted something the sounded right when I listened to tracks or played Youtube. I have noticed a long time now that Parts Express was selling a small flatpack from Denovo Audio that would meet my needs (PN 300-7060), so I finally decided to pick up a pair.


    For drivers I really didn’t have a plan, but when Parts Express ran the Fountek FE-83 on sale for $6.90 I decided to pick up a pair. (I believe the FE-85 PN 296-717 will work in this design too). For a tweeter I pick up a pair of the press-fit Dayton ND20FA-6 tweeters (PN 275-030). Together these made a nice little attractive speaker.

    One interesting thing I found was when I measured the T/S parameters on the FE-83 was that even though the manufacturer lists the Fs at 121 Hz my sample measured at 100.3 Hz, and the Qts was a little lower than specified as well. You don’t often see drivers measuring with a lower Fs than specified so this was a welcome surprise. This led me to decide to make a vented speaker and see if I could pull a little more bass from the tiny box. I ended up using a press-in port that measured 1” x 4” (PN 260-470). This tuned the enclosure to 102 Hz and gives me good half-space bass into the mid 90’s. However, sitting on my desk there is excellent output to about 80Hz.


    For the computer speaker I decided to paint the enclosure. I looked around at different paints and settled on a Krylon textured paint in their “Stone” series called “Obsidian”. This paint turned out to have an excellent contrast with the shiny aluminum cone 3” woofer. Finally, I added little rubber bumper feet on the bottom of the enclosure.



    The crossover is a fairly simple design, because first of all, this is an inexpensive project and second, there is very little room inside this box. All of the components are pretty small. Including the woofer’s inductor where I used a surplus ferrite core inductor that I unwound to 1.0 mH. However, a standard laminate core or iron core should work just fine.



    The frequency response of this speaker is exceptionally flat, and vocals are very clean and realistic. Bass is better than you might expect give the speaker’s size and bass extension.


    And another thing that surprised me was the measured phase response , the speaker turned out to be a minimum phase design, even the Impulse Response shows a single peak revealing the perfect time relationship of the two drivers.





    The impedance is a solid 8 ohms or higher, so a lot of T-amps can drive this speaker without issue. I chose the Topping TP-21 Amplifier (PN 310-310), which works nicely for such close listening.




    So, my final thoughts? I called these the Quarks due to their really small size, certainly the smallest speakers I have ever made. I referred to them as a “Microcosm of Speaker Design” because despite their small size: assembling, finishing, measuring, voicing, etc. is just the same as it is on a larger speaker, so a small speaker doesn’t necessarily mean a small project. But, I think the speaker turned out better than I had expected. I like the look and it sounds exceptional. If I were to do it again the only thing I would change is to not use the binding posts and go with a terminal cup instead. It was really hard to get my fat little hands in that hole to connect the wires to the terminals. But that’s the only thing I would change.







    Believe it or not, after all of this time this is my first project posted in the Project Gallery. :D

    Enjoy,
    Jeff B.
    Click here for Jeff Bagby's Loudspeaker Design Software

  • #2
    Re: The Quarks - M.O.S.D. Computer Speaker

    Very nice Jeff. Micro speakers are becoming quite popular!
    https://www.facebook.com/Mosaic-Audi...7373763888294/

    Comment


    • #3
      Re: The Quarks - M.O.S.D. Computer Speaker

      Very nice. Another micro speaker in the tiny flat pack!

      Comment


      • #4
        Re: The Quarks - M.O.S.D. Computer Speaker

        very nice, I am sure there will be a lot of interest, but the lack of the FE83 will be an issue. A few other available driver options from PE would be great. There is real beauty in this design's simplicity.

        Comment


        • #5
          Re: The Quarks - M.O.S.D. Computer Speaker

          Perhaps Erich H might do a kit.

          Comment


          • #6
            Re: The Quarks - M.O.S.D. Computer Speaker

            Jeff, was wondering if you used any damping material inside? Thanks
            Jeff

            Comment


            • #7
              Re: The Quarks - M.O.S.D. Computer Speaker

              Those look good, Jeff!

              The only note I would make about the textured paints is to make sure and seal the paint after it dries. I like to use a spray polyurethane for this. The reason is that the paint can flake off if not effectively bonded, and the poly-spray helps to keep it intact. Even Fleckstone has a recommended topcoat to seal their own paints.

              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*

              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


              • #8
                Re: The Quarks - M.O.S.D. Computer Speaker

                Originally posted by peepaj View Post
                Jeff, was wondering if you used any damping material inside? Thanks
                Yes, I forgot to add that I used a small handful of polyfill in the box. I didn't weigh it, I just went with the typical density that I tend to use.
                Click here for Jeff Bagby's Loudspeaker Design Software

                Comment


                • #9
                  Re: The Quarks - M.O.S.D. Computer Speaker

                  I can't figure out how to access the Quarks in the Project Gallery.

                  Comment


                  • #10
                    Re: The Quarks - M.O.S.D. Computer Speaker

                    Originally posted by johngalt47 View Post
                    I can't figure out how to access the Quarks in the Project Gallery.
                    Huh? You posted this in the project gallery thread, so you seem to be there.......
                    Click here for Jeff Bagby's Loudspeaker Design Software

                    Comment


                    • #11
                      Re: The Quarks - M.O.S.D. Computer Speaker

                      Originally posted by ontariomaximus View Post
                      very nice, I am sure there will be a lot of interest, but the lack of the FE83 will be an issue. A few other available driver options from PE would be great. There is real beauty in this design's simplicity.
                      That's why I referenced the FE-85, best I can tell it should be a drop in (if I can believe the Fountek data sheets).
                      Click here for Jeff Bagby's Loudspeaker Design Software

                      Comment


                      • #12
                        Re: The Quarks - M.O.S.D. Computer Speaker

                        Nice! Well done keeping costs down and performance high!
                        Melby Audio - Flat Pack Speaker Kits

                        Comment


                        • #13
                          Re: The Quarks - M.O.S.D. Computer Speaker

                          Perfect timing- after building a pair of Minion IIIs, I've been pondering a slightly-bigger [something] for desktop use.

                          Ordered the parts for two pair last night- thank you, Jeff!

                          .
                          Ed Henderson

                          Comment


                          • #14
                            Re: The Quarks - M.O.S.D. Computer Speaker

                            Bravo. Maybe I missed it. Curious as to what a learned one as yourself uses as a power source, and what is the output from your pc, ie: soundcard.

                            Comment


                            • #15
                              Re: The Quarks - M.O.S.D. Computer Speaker

                              These look great! I was wondering what the dimensions are for the mid/tweeter mounting location on the baffle? Thanks for the design Jeff B.

                              Comment

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