Let’s Rock! with Weekend Projects and the MonoBox Powered Speaker

Learn the basics of audio amplification and design your own speaker cabinet to suit your style with our latest Weekend Project, the MonoBox Powered Speaker. MAKE contributor and audiophile Ross Hershberger designed this project around the popular LM386 audio amplifier, a low-power, but highly capable IC. The circuit is designed to accept power supplies ranging from 6V-15V, making it easily adaptable to your car’s 12V power plug, a 9V battery, or a 6V wall wart. The MonoBox has no volume control. Instead volume is controlled by your input source. So be ready, because this amp packs a punch!

Watch the video below to see how to assemble the circuit and install it inside a cigar box. This is a great project to give your own signature touch. The choice of speaker size and shape, grille material, and enclosure are entirely up to you. And since no two will be the same, be sure to send us pictures of your custom MonoBox.

See all of the Weekend Projects posts

24 thoughts on “Let’s Rock! with Weekend Projects and the MonoBox Powered Speaker

  1. I’ve made several recycled portable battery powered amps in cigar boxes using the boards from discarded computer speakers but I’ve never made one ‘from scratch’. Thanks for the post and keep the audio stuff coming. I need a circuit to use as a preamp to power an old spring reverb unit I cannibalized from a broken PA mixer. This may fit the bill.

    1. I’m glad you found the MonoBox project Chuck – I knew you would! There’s no volume control here but that’s what makes this circuit so extensible – lots of options for the user to mod the design to fit their needs. Keep me posted!

      1. I’ve got question: I’ve found a speaker driver that I want to use in this project, but it’s only 4 ohms. Do I need to change the amplifier circuit in anyway? Will there be a major issue from using a 4 ohm driver instead of something that’s 6-12 ohms?

  2. Well, I recently received a great 19 inch Digital TV, but the sound coming out of the in-built speaker was the worst I had ever heard. Mono box saved the day! Bought $12 parts and used a speaker salvaged from the old CRT recently deceased, along with a wall wart from a ancient modem, plugged into the earphone jack on the TV and wala, brilliant sound. Simple,cheap and a screeeeching saver for my ears. I left enough room on the board for a dual monobox design so the mono will be stereo. After all, there were two speakers and a stereo ear jack :)

  3. I made a monobox, but whenever I play that music even somewhat loud, the sound quality quickly decreases. If I turn it down a little it sounds good for a few seconds but then loses quality again. Help!

    1. If you used a 9v battery it is probably drained. I would suggest changing the battery and putting a power switch into your Monobox or removing the battery while its not in use.

      1. I always unplug the 9V. I’ve been told that I probably fried my op-amp, but I replaced it and it didn’t work any better. It’s definitely not the 9V, and it seems like it may not be the op-amp either

  4. Two questions – does matter if you use the LM 368 or 368N and do you have to use 1/8 watt resistors or can you substitute 1/4 watt?

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I'm an artist & maker. A lifelong biblioholic, and advocate for all-things geekathon. Home is Long Island City, Queens, which I consider the greatest place on Earth. 5-year former Resident of Flux Factory, co-organizer for World Maker Faire (NYC), and blogger all over the net. Howdy!

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