Making A Speaker With Resin, Magnets, And Wire

A speaker is just about the simplest electronic component possible, just barely more complex than resistors and wire. They’re also highly variable in their properties, either in size, shape, frequency response, and impedance. Obviously, building custom speakers would be of interest to a lot of people, but there aren’t many people out there doing it. [Madaeon] is one of those people. He created a speaker from scratch, using nothing but magnets, wire, and a bit of UV curing resin.

The frame of the speaker contains a magnet, and the coil of wire is carefully attached to the 0.1mm thin speaker cone with a bit of UV curing resin. All the parts are available on Thingiverse, but you will need a UV resin printer with a low layer height to print this thing out.

The speaker was built by [madaeon] as a demonstration of what the printer he built can do. It’s a fairly standard resin-based 3D printer built around a DLP projector. It’s also cheap, and unlike some other cheap resin-based 3D printers, there’s a reasonable likelihood his will ship within the next few months.

23 thoughts on “Making A Speaker With Resin, Magnets, And Wire

  1. The simplest? Hardly. I guess it depends on your definition of complexity. A coil interacting with a magnet moving a diaphragm is certainly more complex than say, a resistor, a capacitor, a diode, a …….

    1. It’s just an electromagnet, little kids make ’em in school.

      The theory & math and all that a rather complicated, but the actual idea & construction not so much.

      Neat project actually.

      1. Actually making a PN diode or solar cell at home is probably easier. You can do it in seconds with piece of copper wire and lighter to heat it up. Of course you can make speakers too in tens of minutes, but to get some minimal quality of audio needed for listening to music is quite hard.

        1. Making a simple version of something gets you started, it gives you the ‘oh so that’s how it works’ moment. The quality of the sound is of little concern – the “IT MAKES NOISE!!!!” is.

          You can then compare it to better stuff to see how (and why) they do things differently.

    2. Yes it is the simplest… Any young child or an adult can slap one together and get feedback out of it. It may not cohere to stiff specs or aimed frequency response but it will work the complexity is for those who wish to take their newly learned craft further.

  2. Acoustic feedback via microphone, and this would be pretty nice as a way to make custom speakers.
    I often wonder why bass speakers don’t use accelerometers as a way to detect cone-wrecking vibrations to make them more reliable.

    1. this is one of the craziest things I’ve ever read. many reasonings for not doing this:

      1. there is no DC power source at the speaker for a microcontroller (not that you couldn’t suck the energy away from the speaker in one of several ways tho)
      2. the kind of vibrations a speaker has, will undoubtedly far surpass the bandwidth or read speed of the accel/gyro

      But fuck it, I’ll throw my MPU6050 on one of my many subwoofer laying around, play the lowest freq I can get readings at, and check for… G-force? hmm I dunno, what would you check for? I like your idea, and want to see if it’s possible.

      Another option might be simpler, like a cutoff hall effect switch that when reached, triggers a cutting of the power until the hall effect sensor un-triggers? That would likely be a slow to react solution tho, and it only take a couple back plates hits to destroy the voice coil if it wasn’t strong in the first place.

      However, the REAL solution has been available for over a couple decades , pro subwoofer companies like resonant engineering, TC sounds, and many more simply have the Spider (that wavy thing in between the cone and magnet) bottom-out LONG before the voice coil bottoms out, effectively preventing mechanical damage. I suspect most companies don’t do this because it requires more steel/magnet for that extra clearance – and you know no one wants to spend more money than they have to on a product.

      1. This might be possible with something as simple as a zener diode to clip the signal if it goes above a predetermined voltage. It would start to sound terrible at that point, but it would likely prevent serious damage, in theory.

        Might be worth trying.

      2. Accelerometers only tells you the rate of change of speed not actual displacement which is the part you care. You can integrate twice, but the value will drift.

        A simple comparator circuit could easily detect when the average DC value and AC peak from the amplifier is beyond a safe value.

      3. Philips already did that years and years ago with their MFB (Motional FeedBack) line of loudspeakers, the bass performance of these was excellent (a lot better (both in quality and pure Hz) than more conventional speakers), although it did suffer from the mediocre quality drivers used. Somebody at TU Delft actually wrote a nice thesis about this subject, with more modern components and better speakers: http://repository.tudelft.nl/assets/uuid:dbdc165b-31c9-477a-afc6-4093045c8479/MFB_Thesis.pdf

    2. Actually, I think a laser microphone would do a better job at it than an accelerometer- it could pick up the motion, and much more accurately. For that matter, it wouldn’t effect the vibration of the speaker.

      1. Or you could just measure the voltage coming in…

        If you know that, and you know the speaker’s particulars, you can work out how it will move in response to whatever inputs, then just measure the inputs to determine the movement.

        Or you could just put a Zener in, or a PTC or even a lightbulb

  3. If you make your own speakers, you are freed from the compromises that you get with commercial speakers.

    With many bargain ‘audiophile’ systems retailing in 4 to low-5 figures, the speakers are all wound in the same direction, so you get right-handed sound out of your left driver.

    The discerning listener experiences dissatisfaction with such systems, but until has heard a system with correct windings, he cannot recognize and name it as a lack of chirality.

    1. This!! For so long I have been trying to explain that my oxygen-free copper Spirao (TM) stereo speaker system outperforms *any* comparatively priced system due to its unique coil windings.

      Left and right speaker coils are wound independently in my company’s factories in Kansas, USA, and Buenos Aires in Argentina. Depending on the customer’s location, either one of them is carefully turned over when shipping across the equatorial region.

      This leads to an unsurpassed audio quality that *anybody* can recognise.

      Operators are standing by. Call today!

  4. Motion feedback is fairly common in self amped speakers for PA use. It has done to PA’s what negative feedback did to amps at the beginning of the 33 LP era. I made a spring reverb with sigma drive to the coils, It went from the boingy resonant sound to flat even delay like a good digital echo.
    Good hack, but lots of dirt and stuff on the cone. Is it hair reinforced?

  5. it wasn’t from scratch. he didn’t mined the minerals and metals and synthesed them and produce magnets and forged other parts. also didn’t gathered the resin and processed it.

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