Sound-o-Light: simple and interesting DIY speakers

This is a great project for a slow afternoon, or a beginners introduction to DIY. [William] shows off a really simple speaker project that results in a light show as well as a decent enclosure. He’s using a PVC elbow to mount the speakers. They’re just glued in place. Below that, a section of clear tube allows for the lighting effects and a flange at the bottom supplies stability. For the lights, [William] opted to forego any complicated electronics and simply wired LEDs to the speakers themselves.

Admittedly we’ve seen more complicated systems in the past, but his results are quite nice and could be done pretty fast.

Comments

  1. Zee says:

    This is step by step out of make volume 31

  2. MorbiousStone says:

    thats awesome !!!

    • Drone says:

      This is Dumb…

      He wires three high-intensity LEDs in series and puts them all across the speaker terminals.

      Let’s assume the forward voltage drop across each LED is 2 Volts, then the forward drop across three LEDs in series is 6 Volts. The three LEDs in series connected in parallel with the speaker are half-wave rectifying (clipping) the audio signal when the signal exceeds the forward drop of the series connected LEDs.

      When the audio signal exceeds the 6V forward drop of the three series LEDs, the LEDs light up – and distort the audio signal. A 6 Volt peak sine wave into an 8 Ohm speaker is 2.25 Watts RMS (provided the stupid LEDs aren’t in the circuit of-course). Audio below 2.25 Watts RMS will not light the LEDs.

      This is a really bad design; typical of this whole “Make” movement. Don’t waste your time messing around with this. I think this guy made this video just so he can stick the advertisement in the middle.

      If you really want to add LEDs to some speakers, buy some small dirt cheap One-Hung-Lo brand PC speakers, rip the little chip amplifier board out of them, and drive the LEDs with the amplifier fed in parallel with your regular audio amplifier, or by putting the little amp inputs across the speaker terminals via a high impedance resistor voltage drop network.
      Remember to put resistors in series with the LEDs to protect both the LEDs and the speaker amplifier chip. You’ll have to do a little measuring with your multimeter then Ohms and Watts law calculating to figure out the resistance and power specifications for the resistors.

      An advantage of this amplifier approach is that it avoids distortion and allows you to adjust the LED brightness level independent of the music level (and independently for each speaker provided your amp has a balance control). The drawback is added complexity and having to separately provide DC power for amplifier board.

  3. n0lkk says:

    Playing a youtube video through PC speakers it’s really hard to judge how good, or bad anything actually sounds. A great novelty item. The only drawback I see is a high volume requirement to get the light show, the inclusion of a powered light organ has some merit of consideration.

  4. Galane says:

    Wouldn’t the LEDs distort the audio by acting as a half wave rectifier?

    Would be nice if this article showed how the LEDs are connected.

    ‘Course what’d be most appropriate to play through a PVC pipe speaker enclosure would be “PVC IV” by Blue Man Group.

    • macona says:

      They will make a difference. I dont know how much. It would be better to drive them off a mosfet or something capacitivly coupled to the speaker, but then you would need extra power for wires.

  5. macona says:

    Ooo. Clear PVC pipe. That stuff is spendy!

  6. mrguy99493 says:

    Sony sountina is more betterer. It uses the pipe as the ‘cone’. Usual 1/r^2 volume doesn’t apply since its a line-source, not a point source -> 1/r.

  7. Anka06 says:

    That is great!

  8. Draget says:

    The design is pretty nice, but I agree with Drone, the electrical design is nothing I would like to see in a magazine promoting such builds.

    LEDs directly across the terminal is a pretty dirty hack. And a basic circuit to drive them independantly from the source signal is not that hard – throw in some RC to get even a nice bass-filter. Even without understanding the exact way how it works, I had done such sound-2-light modules years ago when I was still a novice. Nothing too hard!

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