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Elder Bluetooth Speaker Build

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  • Elder Bluetooth Speaker Build

    Hi Guys

    This is my attempt at a speaker design from Kirby Meets Audio. Its his Elder design that i added my own twist to.
    All of the electronic components are as per the KMA plans including crossover design so i can not take any credit for that.

    Its my first attempt at a speaker build and i am HOOKED!

    I can see me being regular here to learn as much as i can about speaker design principles.

    Main box is made from Select Pine, stained black, burnished with steel wool and then clear coated with wipe on poly.
    Front panel and rear panel is made from Red Oak and dyed red with Keda Dye and then clear coated with polycrylic.

    Although i am happy with the way it sounds its not quite as loud as i had hoped, is this limited by the Amp or by the components themselves?
    I have the on board volume maxed out and the the volume on my cellphone maxed out too. Its pretty loud but not as loud as i had expected.

    Drivers are Dayton Audio RS100-4Woofers
    Tweeter is Dayton ND16FA-6 5/8 Tweeter
    BT Amp is Wondom AA-AC11161 2x30W 4-8 Ohm Class D

    Anyway, let me know what you think

    The original design Elder from KMA

  • #2
    What is your power source and what is the voltage?
    "A dirty shop is an unsafe shop, if you injure yourself in a clean shop you are just stupid" - Coach Kupchinsky

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    • #3
      Wow, you knocked that thing out of the park! How did you apply the ripples around the woofers, very cool looking.
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      • #4
        Originally posted by BorneoBen View Post
        Anyway, let me know what you think
        ​Wow--very nice effect with those ripples in the oak. Looks great--totally outclasses the original version.
        Free Passive Speaker Designer Lite (PSD-Lite) --


        • #5
          I bet a core box bit and the jasper jig with plunge router did the ripples. Nice work, ive been watching his youtube videos they are good. I still have issues getting frd's blended and everytime i open pcd it seems to change settings when i load a design up. Theres a ton to learn and its overwhelming but if you stick with it you will have your own designs.
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          • #6
            Thanks for the nice comments guys

            Gordy to answer your question its a 19volt 4 amp power supply but i also have internal batteries, 6 x 18650 cells wired 2p3S to double the capacity.

            To answer the other questions about how i did the ripples.

            Well, i guess you could call it cheating a little... I have a CNC router, its all my own design but it was machined.
            There is still a fair amount of hand finishing and the box was made with traditional wood working techniques.


            • #7
              I really liked the KMA design but i also like to make things my own and as original possible.
              Its too easy to just copy something.


              • #8
                Wow, love it, nice job!


                • #9
                  The ripple idea is really cool looking, I've not seen it done before. Are both of the amps channels connected or just one?


                  • #10
                    Thanks Guys

                    Jeff, yes both amp channels are hooked up properly, the tweeter runs off one channel only.


                    • #11
                      Gordy hit upon the PS voltage. But at 19 V you should be getting a nominal maximum of 45 W into each 4 ohm RS100s. The 2x30w amp will deliver as that is a sine wave calc. and music doesn't produce anywhere near as much power. On 2p3S Lipos, you'l drop down to a nominal maximum 18 W rms per channel.

                      I'd bet you don't notice a difference between the AC PS and the 2p3S batteries (EDIT: because your not getting anywhere near max output).

                      I suspect the problem is the gain of the amp. Sure lists the gain at 20 dB (e.g., 10x voltage gain). A phone/mp3 player outputs are too low of an input signal to get full power. Try driving the wired input with a PC or laptop. Both my laptop and PC will put out 1.4 Vrms at max volume. That will translate to 14 Vrms at the amps outputs (e.g., 1.4 V x 10x gain). And that should drive the amp beyond full power into clipping.

                      I don't have a solution for the BT input short of modifying the board to select a higher gain supported by the TPA3118 chip.

                      BTW: Most excellent looking box.
                      Last edited by Millstonemike; 03-02-2017, 05:57 PM.


                      • #12
                        Thanks for the feedback Mike

                        Yes i think you are right i get a louder output from the wired Aux In and a different source.
                        Thanks for the explanation.

                        Is it really possible to modify the board to select a higher gain?

                        I guess the simplest solution would be to replace the amp with a higher power one.




                        • #13
                          Originally posted by BorneoBen View Post
                          Thanks for the feedback Mike

                          Yes i think you are right i get a louder output from the wired Aux In and a different source.
                          Thanks for the explanation.

                          Is it really possible to modify the board to select a higher gain?

                          I guess the simplest solution would be to replace the amp with a higher power one.


                          I haven't worked with this board. But the chip's gain is set by two surface mount resistors typically very close to the chip. The chip supports 4 gain settings based on the value of these two resistors: 20 dB being the lowest gain setting. The values required to select a particular gain setting are clearly spelled out in the datasheet.

                          I had a TPA3116 2.1 amp with the chips set at 26 dB gain. That's still not enough for phones to drive to full volume. My amp was wired input only. So, I front-ended the amp with the Sure headphone amp. The Sure headphone amp acts just like a pre-amp (albeit only a couple of K ohms input impedance) and adds 9 and 15 dB additional gain depending on a dip setting.. That worked very well for me. But it doesn't solve the BT volume issue.

                          If I were going BT, I use the discreet Sure BT module, the headphone amp and a TPA3116/3118 power amp with both BT module output and a discrete wired input in parallel to the headphone amp input and then the headphone amp output to the power amp (maybe with a switch to select the between the wired and BT signals).

                          And just to be clear, you could have a 1000 W / channel amp. If the input signal strength is low vis-a-vis the amp's gain setting you'll never get more power out than your getting now.

                          See this paper I wrote explaining amp gain versus signal level and power out:



                          • #14
                            Beautiful! I like the rounded case, reminds me of a Peachtree amp.

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                            • #15
                              This looks awesome! Can this problem be caused as tweeter uses one channel? Is there a way to bridge two channels over the tweeter?For example, using two two-way crossovers and after adding some resistors on highpass to limit the current, then power the tweeter. This is not an idea, in fact, a question. I'm a super noob and I want to learn this stuff by reading different forums and resources on the web.