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Build process - sharp inspired 3d printed ghettoblaster (half size)

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  • Build process - sharp inspired 3d printed ghettoblaster (half size)

    Hi all,
    its been brought to my attention i have more than one project on the go and it is starting to get a bit confusing with what im asking in relation to which DIY job. SImilar to the boozetooth BT speakers, where i got up in the revisions due to design improvements. Originally this project started off as a full size Sharp GF 6565 to be printed and housing the W130 X - 2x4 woofers with the matched visaton full range driver, which got put on hold due to having issues with the printer than could indeed print 500mm high....

    for a bit of fun and an excess of DMA45-8 drivers, it became a pair of them and 1x peerless 3.5inch passive as i had a couple in my garage i've never been able to use....this one became a failure due to trying a DIY hyrodip (spray cans, water and a bucket) and no matter what i tried the paint just would flake off and filled in the small details.

    3rd iteration was the same print, but in white. The issue with this one was having 35mm internally which was fine to slide a driver in, but was impossible to glue in items and screw as it was one piece.

    4th iteration was printing it like a traditional ghetto blaster would have been having front and rear panels that would ulimtately be glued together once assembled. This time the issue was the BT/AMP and the pot and additional SPST switch soldered to the board, it had too much interference and was continually browning out no matter what boost module i used. Also wondered if my original quarenteenie build sounded better with these smaller speakers as it had individual enclosures and not a shared one like the 2 above (listed as a failure). this one sampled a filter, which i dont know if it was causing the brown out, but it did appear to not fail as much when bypassed.

    Now to the latest one currently rolling off the printer as i type (almost finished). The intention was to run 1x DMA45-4 with 1x ND90 PR per side, the rear and front panels were also designed to snap into place providing an air tight seal between the 2 sections. As i was reverting back to a previous amp choice (trusty QCC3003 module from the boozetooth's) i decided to do a little more design to look like the original unit with some uselss extra switches/knobs and a cosmetic spectrum analyiser. I also had about 100 of these 3mm magnets, where i designed them into the grill and front panel to assist the grill in holdiing in place. if they rattle off ill epoxy in.

    Yes i know this isnt everyones cup of tea and a bit out there (weird even), but im civil engineering designer by trade, enjoy the 3d side of things and being able to print and make these models usable makes it all worthwhile in my opinion. I would be happy to provide the CAD if somebody wants to give this a go.

    Now for the internals.

    - Dayton Audio DMA45-4 x2
    - Dayton Audio ND90-PR x2
    - 1x 1KG Roll of PLA (approximate only could be less)
    - QCC3003 2x5w BT AMP
    - MT3608 buck converter
    - 2200uF capacitor
    - rocker switch
    - Sony VTC6 3000mAH 18650 battery
    - couple of LED bulbs and resistors

    Something worth noting, you can program the BT modules, change EQ settings, change the name etc, which wasnt done for this as i misplaced the pogo pins clip. Natively supplying 5v's to these will give you 3w per channel at 4ohm, but they also mention that going 6.5v will give you 5w per channel, nothing to win a sound off at the local car meet, but not bad for a bit of portable fun. You can also solder a couple of momentary switches to control the volume, pre, next, play and pause, plus answer the phone (never tried the last one).

    the below graph was based on the different scenario's

    black - added 2g to the passive to lower the f3 to around 90hz. if the weight was removed it would model similar to the DMA45-8, but with a peak just shy of +2db and would be tuned to a F3 of 100hz. I wasnt sure if this would be a better option and be like the RS100 build in the actual 40 year boombox, where the higher F0 gave more the perception of bass. if 7grams of weight gets added it models very similar to the peerless passive scenaio with the dip from 200hz. I would be keen to know if this is similar as i can make this change relatively easy.

    yellow - This option was using the Peerless 3.5inch passive, but requires 0.01cuft, which might not be achieveable unless using stuffing or some form of filler. This PR is quite large and might not actually fit even if was the better solution as 1 can fit, but would require the drivers sharing, but 2 definately wouldnt. This option was shelved as printing larger pieces on a 240 dia bed was preferred.

    blue - similar to the first option, but using the DMA45-8 driver, with no weights. This was the original option, but with the change of BT/AMP, meant the output would go from 5w's to 2.5w per channel. I sampled this and just wasnt the loudness i wanted from, so shelved it.

    Potentially i could have gone KAB board with the 12v battery board, but i just dont think i could get everything in the size i was going for. Potentially maybe a 3S configuration with the 16350's and some major redesign internally, but i think it would go past the point of return and sound average....

    I also considered using the ND90-PR's with a ND65 driver, but just didnt want to sacrifice the additional 20-25mm of depth required to put a larger driver in a 3d print like this.

    Attached Files
    Last edited by 3rutu5; 10-30-2022, 04:15 AM.

  • #3
    Some random CAD view and some others
    almost got.a 26650 in there but just a few mm's too I can position the tp4057 on the back of the battery mount and the USB c jack just below it, might be able to glue the step up module there as well for some good cable management
    Attached Files


    • #4
      Well, even if your posting is a bit disorganized, your work is very nice. Hope to see this completed and hopefully painted to mimic the original.

      I'm stuck in wood, table saw and router land.


      • #5
        Originally posted by djg View Post
        Well, even if your posting is a bit disorganized, your work is very nice. Hope to see this completed and hopefully painted to mimic the original.

        I'm stuck in wood, table saw and router land.
        I think after the first attempt that I may pass on the painting, the photos don't do it justice and looks ok straight off the printer. Maybe a splash of colour across the face, who knows but I do know sanding would be a pain with all the small details.

        Nothing wrong with timber, been using my wooden boomboxes lately as well and love that sound.


        • #6
          Getting a little closer, had some fun with some small 3mm magnets to have the grill attach that what....don't know If it will cause any issue with the hardware, but don't think it will.

          Did a.little soldering as well and it looks to be working but didn't attach the speakers yet as I misplaced the crimped terminal connectors. The problem I'm having with the dma45's is the soldering iron gets hot and.the plastic housing works its way loose (on the driver)

          Also put the handle on might need some. loctite to stop the bolt coming off.

          Most a.test run tomorrow and hot glue some areas an epoxy the shells together.
          Attached Files


          • #7
            Man, something inside me just thinks this is so cool. Keep going!

            Zarbo Audio Projects Youtube Channel: * 320-641 Amp Review Youtube: *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


            • #8
              All wired up and ready to go, I wont expoxy the body together yet until i'm a 100% happy with how it all works as it is easy to fiddle around the internals with the front off. But let me just say, tried the no weight option, then added 2g's (some washers i had int he garage), but it on with blue tack and i could notice the slight extra punch, not heaps but noticeble. Im tempted to go 4g's and see what that does, just didnt look that nice on the graph. So...whats different? i wired up 4 LED's in parallel, each with their own resistor just off the switch and put 3 behind the "power bar" (on the Actual gf 6565) and it looks pretty cool, the other one was hidden and i'm sort of bummed that i forgot to design the visible bulb and have it light up, but it does come through the PLA plastic quite well when on.

              The 3mm magnets also make mounting the grills really easy and im glad i did it, just wish i had a time machine to go back over a year to do the same on the phantom clone.

              Now the sounds, i was running tests with like for like setups, where the unit to the left was the other small DMA45-4 build i did, running a similar amp, battery and boost setup. The only real differences was the 2 drivers shared the same enclosure, maybe 15-20% smaller and i went with some random pairings of passive membranes and DMA58-PRs (difficult to model). So yes the new one completely smashes it out of the park.....If i was compairing WiniSD charts (albeit not being able to accurately modell an extra 4 passive membranes), the F3 on the new one is around 92Hz (F0 100hz, F6 87hz, F10 82hz), where the other was (F0 400hz, F3 180hz F6 123hz, F10 94hz). The other noticable difference was the left unit used a 18350 1200ma battery, where the right one has a 18650 3000ma and assuming the LED's dont actually draw that much each 20ma, that the new one should exceed the 8 hour run time the previous did.

              Great other little feature, this all gets charged off a usb c jack, so any new phone chargers and power banks can be used.

              Final thoughts? i really quite like it, could i have done one with a 12v system? possibly, could i have gone 2 sealed chambers and put a tang band 2.5 sub on the back? maybe.....but i might have an issue putting it all in a tiny space. Do i like it, YES i do really like it, just wish the print in places with the smaller detail was a little crisper, but having an approximately 40 hour print to do it all is enough for me, less than a roll as well. I'll post a youtube video so people can hear how it actually sounds.
              Attached Files


              • #9
                Only other thing i was thinking was to drill a small hole in the back and put in an antenna, purely cosmetic, but had a small one lying around.


                • #10
                  Loving it so far, expoxied on the panels and siliconed up some gaps around the usb c and switch. Ran it non stop today for 9h30mins and it is still going strong, hit pause on the stop watch and will continue all day again tomorrow. I'm thinking is the 18350 1100ma battery gave me around 7-8 hours of run time that a 3000Ma 18650, even with those 4 LED bulbs going will give me around 18-22 hours, maybe more.

                  Was thinking about the advice on the bass shelf for the DMA45-8 and if i should try it with this or just let it be, just the risk of it distorting or not being as good...who knows to be honest.

                  Fun little project would consider doing again in the larger scale, but as mentioned before, if you have a 3d printer and want a go, just shout out.


                  • #11
                    So cute!!!
                    Isn't it about time we started answering rhetorical questions?

                    Paul Carmody's DIY Audio Projects
                    Twitter: @undefinition1


                    • #12
                      Sadly it lasted 11 hours of continuous play until it turned off. Still very happy with that


                      • djg
                        djg commented
                        Editing a comment
                        You mean the battery was drained or the electronics broke?

                      • 3rutu5
                        3rutu5 commented
                        Editing a comment
                        I reckon the battery drained. I might have got longer if I didn't go 4 LEDs possibly. I put it back on charge and it started going again.

                        I really liked the cosmetics look of the LEDs shining through the PLA so in the case sensibility was left out and the common ground was having a 10-11hour run time. A thought was to use a momentary/tactile switch to toggle on the lights on demand. Maybe if I ever rebuild this one I'll look at that with some battery indicator/voltage meter etc

                    • #13
                      I've decided not to push a good thing and instead make one for a mate. It is pretty similar but I've changed the back end a little to have tapers to avoid the rough surface from the supports and it seemed to work a treat.

                      The amp chip that came was different but I can still access it via my computer and give it a bass shelf filter though the DSP.

                      He wanted an all black one, which most looks good but even though the filament is matte I feel like there is some artifacts when the light hits it in the right light.
                      Attached Files


                      • #14
                        After a nice weekend away I decided to finish off the day by assembling this one for my mate. Interesting to note that i played around with the DSP on the board with this one and installed a Bass Shelf filter of about 2Db's from the 150hz range and also dropped the entire master by -2db's as well to stop and saturation of the signal. So guess what would people want to know, how does it sound? well to my ears against my white one it seems to have more slightly more bass, just looks to hit a little harder and without distortion (like my other). I dont think it has an issue with the cone excursion as we are talking 5watts per channel on a 6.5v system, but to me seems to be the perfect matched amplifier for the DMA-45's. This is purely my opinion as i have a tendenacy to push the limits of the builds and after testing a dozen 12v and 5v amp chips i'm very impressed by the QCC range over the CSR BT chips, only issues being that a QCC3003 and 3005 chips seem to be on the way out and might be harder to find and modify.
                        Attached Files