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Make: Projects

New Project: Sound-O-Light Speakers

Surprisingly simple PVC pipe speakers are clear shining performers.

While tidying up my workshop, I found some clear 3″ PVC pipe left over from a spud gun project (the Nightlighter 36 taser-powered potato cannon in MAKE Volume 03). Clear PVC is one of my favorite building materials, but it’s expensive, and since the last thing I need is another potato cannon, I wanted to come up with a project that would make good use of its unique qualities.

Clear PVC is stiff and dense, which makes it excellent material for audio speaker cabinets. I had seen uniquely shaped speakers made from regular white PVC, so I wondered if clear tubing could make decent-sounding cabinets that also generate lighting effects.

I connected an iPod (playing ZZ Top’s “La Grange”) to a 20-watt amplifier and a small speaker, and played around with different configurations of LEDs on the speaker wire. The best visuals, I found, came from simply connecting 3 ultra-bright LEDs in series, in parallel with each speaker. Voilà! At moderate volume and above, the same audio signal both drove the speaker and pulsed the LEDs in time with the music — and I discerned no difference in the speakers’ sound with or without the LED load.

Introducing the Sound-O-Light Speakers. They’re easy to build, they get surprisingly good sound out of their single 3″ drivers, and they look hella cool.

Materials

  • Speaker drivers, 3″ diameter, round (2) I used HiVi B3N drivers, which are popular, cost about $10 each, and use standard car-audio spade connectors. If you have a different 3″ driver in mind, by all means give it a try.
  • PVC pipe, clear, 3″×20″ lengths (2) Some sources sell this by the foot while others only sell 10′ lengths. Since this pipe costs roughly $15/foot, it makes sense to find a supplier that can sell the exact 40″ quantity required. Check local industrial plastics suppliers first, but there are also several online sources.
  • PVC pipe flange fittings, 3″, white (2) ABS fittings may also work, but ABS is not as stiff or dense as PVC, which may affect audio quality.
  • PVC pipe elbow fitting, 45°, 3″, white
  • Audio binding posts (4) typically sold in pairs
  • Aluminum tubing, 1/2″ outside diameter (OD) × 17-1/2″ long (2)
  • LEDs, 5mm, ultra-bright (6) your choice of color(s); they can be different for each speaker.
  • Spade connectors, female, .110″ (4) standard car audio connector
  • Cable clips, adhesive-backed, plastic, sized to hold coaxial cable (6) for holding LEDs. You can also use hot glue.
  • Speaker cable, 2-conductor, 6′ or other paired wire. We used a red/black pair to help identify the polarity for the LED circuit.
  • Hookup wire, insulated, 18–22 gauge, 4′
  • Silicone adhesive in squeeze tube

For bass reflex speakers:

  • Bolts, #12 round head, 3/4″ long, with matching nuts (8)
  • PlastiDip or 6″ hardwood square (optional) to prevent bolts from scratching floors or furniture

For acoustic suspension speakers:

  • PVC or other plastic sheet, 1/4″ thick, 1′ square minimum Look in the window and door aisle at your home improvement store.
  • PVC cement
  • Silicone caulk

For powered/transistorized option:

  • Snaps for 9V battery (2)
  • 9V batteries (2)
  • Transistors, NPN, TIP31 type (2)
  • Resistors, 220 (2)
  • Switch, on-off toggle
  • Perf board

Make Amends

In Volume 31’s “Sound-O-Light Speakers,” the vented build option is not a true bass reflex design (see reader Louis Lung’s letter, here). Also, author Bill Gurstelle’s Night Lighter 36 spud gun project is from MAKE Volume 03, not 04.

  • William Gurstelle

    Sanjaya,
    There are a lot of online suppliers – Mcmaster.com, grainger.com, and so on, but they all charge a lot for clear pvc. I see this website that offers it for much less but I know nothing about them:
    http://webcat.rhfs.com/familydetails.aspx?FamID=421
    You can consider building it out of less dense and strong acrylic which is cheaper, but I can’t vouch for how it sounds since I’ve not tried it. A source for that is
    http://www.aquaticeco.com/subcategories/826/Acrylic-Tubing?green=447575FA-C464-5C26-B46F-4EBE5E54E181

    You can glue or friction fit, depending on how sturdy you want it be and if you think you’ll ever want to take it apart. I just friction fit and left it at that, except for attaching the speaker.

    3. Use a fine toothed blade on your saw if you’ve got one, although it doesn’t much matter.
    William Gurstelle

  • William Gurstelle

    That’s the audio amplifier.

  • Goli Mohammadi

    Looks great, Ed! Thanks for sharing!

  • jake

    hey, can you send me the schematics for everything ? jake.malo@hotmail.com

  • Shane

    Can I use 2.5 inch clear pvc pipe instead of 3 inch? 2.5 inch is much less expensive.

  • Jon

    My son was incredibly excited to try this for months. Finally got around to trying it. We just got done hooking up the LEDs and they worked great…for about 30 seconds. I turned the volume up to get them glowing brighter and they burned out. I thought it was the wiring, but tried some other lights and they worked, then burnt out. I am guessing they need a resistor in line to avoid burning out, but there is no mention about this for the unpowered option. I wasted about 8 bucks worth of LEDs and now have to go get more and lights and resistors to try to fix it. Can you add in some warning and methods to fix this on here?

  • Patrick Martin

    When I use the power circuit for the LEDs, the speakers cut out when I turn the volume up too high. Without the transistor circuit, everything works just fine. Am I somehow overwhelming the transistor with the high volume? I’d really prefer the powered version, but the volume limit I’m experiencing is just too low. Any ideas or suggestions?

    • Patrick Martin

      I’ve fixed the problem by putting a 100K resistor between the transistor’s base and the speaker, and it works fine now. But I haven’t figured out why that works or what the problem was.

  • Patrick Martin

    My stepson and I just finished this project, and we had a lot of fun! We tweaked the design a bit. We painted the flange and the 45 degree joint black with Fusion paint. We also added a second set of 3 lights at the bottom of the speakers as well, connecting that set in parallel to the set at top, so it could still be powered by a 9V. Finally, we mounted the 9V circuit in a mint tin, with plugs to connect to the speakers/amp and the send the power to the lights.

    As I noted in an earlier comment, I needed to put a resistor between the transistor’s base and the speaker, or else it kept tripping some sort of protection circuit on our amp when the volume got too loud. I wound up with a much smaller one, about 2.7K Ohm, I think. I still don’t understand why that wound up being necessary, but it works perfectly now.

    Next, we’re going to try expanding on the electronics, to have filters so that there’s one color light for bass tones, another color for higher notes, etc. I’d also like to configure to let it be powered with 5V and use a mini-USB connector, with or without a rechargeable battery. That would require changing the configuration of the lights, to do several parallel sets of 2 LEDs rather than 1 series of 3 LEDs as in the current design.

    This was a great first project for us to work on, just the right mix of fun and complexity and learning thrown together. Thanks!

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