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.

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

Jake Spurlock on November 30th, 2012 at 10:19 am said:

Love the gif. So much.

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chuck on November 30th, 2012 at 10:47 am said:

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.

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- Nick Normal on November 30th, 2012 at 11:03 am said:
  
  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!
  
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  walkindude125 on March 30th, 2013 at 10:28 am said:
  
  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?
  
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Wally Sorich on December 2nd, 2012 at 1:53 am said:

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

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Brian Dorsey on April 15th, 2013 at 3:26 pm said:

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!

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- Dawoo on May 28th, 2013 at 5:28 am said:
  
  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.
  
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  Brian Dorsey on June 7th, 2013 at 11:03 am said:
  
  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
  
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