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  • ABC Bookshelf Speakers

    The main idea behind this build was to test and see if using an Aperiodic Bi-Chamber box would work well for bookshelf speakers. I had used the design a couple times for subwoofer enclosure but never for full range speakers. Here is a website that explains a little more detail about ABC boxes http://www.diysubwoofers.org/prt/dual_chamber.htm

    I have a set of Elemental Design e3.65i component speakers that were collecting dust so I decided to put them to use. I know ABC box is more designed for subs but WinISD was suggesting a ported box with a volume of 1cf tuned to 38 Hz with an F3 of 33 Hz. So with that low of tuning I wanted to see what the output will be like having two tuning frequencies and if it has the same positive results as the sub boxes I have built in the past.

    Now the design, it is a 1.2 cf ABC ported box with the large chamber tuned to 33 Hz and the smaller chamber tuned to 48 Hz. The box is 10" X 18" X 16" and has a front facing and rear facing port. All the edges are rabbit and dado rabbit on the inside.

    Click image for larger version

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    For now I left the boxes unfinished until the weather is a little nicer here in Iowa. First impressions are WOW, the speakers have a 92 db sensitivity so it does not take much to get them going but the low end output from a 6 1/2 inch speaker is crazy. I filled both boxes with polyfil but I think I am going to remove the polyfil and just use a thick piece of cotton insulation because the mid bass is being choked off. The crossover has a -3 db switch for the tweeter that I am going to use to soften the highs. But other then that, these are amazing. If I have some free time I would like to build the same box 1.2 cf box but have it be a plain ported box and see what the possible differences would be but for now I am very happy with the ABC bookshelves.
    If we all reacted the same way, we'd be predictable, and there's always more than one way to view a situation.
    What's true for the group is also true for the individual. It's simple: Overspecialize, and you breed in weakness.
    It's slow death.

    //Burn n' Die//Dream Weaver//Maximus//ABC Bookshelf Speakers//Dayton Twin Towers

  • #2
    Re: ABC Bookshelf Speakers

    Update: I replaced the polyfil with a piece of cotton insulation and really help improve the mid bass response. Like I mentioned before, I plan on doing 3/4 round over on the ports and vertical edges.
    If we all reacted the same way, we'd be predictable, and there's always more than one way to view a situation.
    What's true for the group is also true for the individual. It's simple: Overspecialize, and you breed in weakness.
    It's slow death.

    //Burn n' Die//Dream Weaver//Maximus//ABC Bookshelf Speakers//Dayton Twin Towers

    Comment


    • #3
      Re: ABC Bookshelf Speakers

      I believe this is called a Dual-Chamber Reflex (DCR), not an ABC... It's not an Aperiodic alignment.
      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


      • #4
        Re: ABC Bookshelf Speakers

        Are there any big disadvantages besides the extra work with this kind of alignment?

        Comment


        • #5
          Re: ABC Bookshelf Speakers

          Originally posted by Wolf View Post
          I believe this is called a Dual-Chamber Reflex (DCR), not an ABC... It's not an Aperiodic alignment.
          Doesn't it accomplish the same thing? I've seen these used in car audio before. I think the net effect is the same as aperiodic loading.
          Bryan K.

          Midwest Audio Club

          Speedster | Sub Attach | The Wildeman | Sean's NLA Towers | COGAR, COUGAR II and COGAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

          Comment


          • #6
            Re: ABC Bookshelf Speakers

            Originally posted by bkeane1259 View Post
            Doesn't it accomplish the same thing? I've seen these used in car audio before. I think the net effect is the same as aperiodic loading.
            No. An Aperiodic enclosure vents with a tuneable vent that makes a sealed drver think it's in a larger box. A Dual Chamber Reflex on the other hand has 2 tuning frequencies, this allows better control. IE. the driver cone excursion is close to or above Xmax in a standard ported design at the midbass frequencies, this allows better control of Xmax with the higher tuning of the smaller chamber, this allows one to tune the over all enclosure to a lower F3 and tames the drver excursion at both the higher and lower tuning frequencies, allowing the lower f3 to be set approx. 1/3 octave lower.

            Comment


            • #7
              Re: ABC Bookshelf Speakers

              An Aperiodic changes the Qtc of a sealed system, and is mainly seen as a very leaky box. I would not say it allows the driver to see a different volume.
              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: ABC Bookshelf Speakers

                Originally posted by Wolf View Post
                I believe this is called a Dual-Chamber Reflex (DCR), not an ABC... It's not an Aperiodic alignment.
                Later,
                Wolf
                +1
                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
                  Learn something new every day.
                  Bryan K.

                  Midwest Audio Club

                  Speedster | Sub Attach | The Wildeman | Sean's NLA Towers | COGAR, COUGAR II and COGAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

                  Comment


                  • #10
                    Re: ABC Bookshelf Speakers

                    Not to beat a dead horse, but increasing the volume changes the Qtc... so what's technically the difference?

                    Comment


                    • #11
                      Re: ABC Bookshelf Speakers

                      The Volume is not increased, just divided and tuned.
                      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


                      • #12
                        Re: ABC Bookshelf Speakers

                        Thanks for all the input, I have to say, I really like the output and sound quality from these guys. I don't think I would go crazy and use this box design in a tower, but for a couple bookshelf speakers that generate a full range, not bad. I really wish I had an OmniMic so I could display what the output is like and not just say they sound good. If I get a chance to make it to a DIY meet, I will have to bring them as a unique design.
                        If we all reacted the same way, we'd be predictable, and there's always more than one way to view a situation.
                        What's true for the group is also true for the individual. It's simple: Overspecialize, and you breed in weakness.
                        It's slow death.

                        //Burn n' Die//Dream Weaver//Maximus//ABC Bookshelf Speakers//Dayton Twin Towers

                        Comment


                        • #13
                          Re: ABC Bookshelf Speakers

                          Finally picked up the OmniMic and here is the response from the boxes.

                          Click image for larger version

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                          As you can see it holds strong down to 30 Hz. :p
                          If we all reacted the same way, we'd be predictable, and there's always more than one way to view a situation.
                          What's true for the group is also true for the individual. It's simple: Overspecialize, and you breed in weakness.
                          It's slow death.

                          //Burn n' Die//Dream Weaver//Maximus//ABC Bookshelf Speakers//Dayton Twin Towers

                          Comment


                          • #14
                            Re: ABC Bookshelf Speakers

                            That response isn't too shabby for a component set, good work, enjoy them

                            रेतुर्न तो थे स्रोत
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                            in war, victory . . . in peace, vigilance . . . in death, sacrifice.

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                            • #15
                              Re: ABC Bookshelf Speakers

                              Originally posted by Thumper Tom View Post
                              Finally picked up the OmniMic and here is the response from the boxes.

                              [ATTACH=CONFIG]35599[/ATTACH]

                              As you can see it holds strong down to 30 Hz. :p
                              My style of bookshelf!! Getting lowwwwwwwwwwwwwwwwwwwww.....:D
                              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

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