Retro ‘Drive-In Speakers’ Upgraded with MAX9744 20W Class D Amp, RGB Encoder, and More! #MusicMonday
Want to add some oomph to an old pair of ‘drive-in’ speaker enclosures? Take inspiration from Dan Rasmussen’s project over on Make: Projects. It’ll not only add some audio amplitude to your speaker set, it’ll make them visually interactive as well, using an optional electret microphone to flash a RGB LED to the beat of the music coming out of the speakers. Clever! And you can always tell a good project because the how-to goes above & beyond the mere technical step-by-steps and includes some good pointers and tips-and-tricks that you may find useful for your own mods and builds.
And you know at 20W those speakers sound bumpin’!
When I was a kid we went to the drive-in theater to see movies like The Legend of Boggy Creek and Evel Knievel. I loved those movies but I remember just as vividly those retro-cool metal speakers that entered into our car for these campy films. A few years ago I found one of these speakers at a flea market and it came home with me.
After it sat in my garage for years, I finally decided it needed to be what it was made to be: a speaker. But this time it gets some pretty nice power and technology, as a 20-watt amplified stereo speaker set with an RGB lighted dial that first dials in your volume by color and then, with a click, pulses to the beat of the music. It’s all done with 4 modern off-the-shelf circuit boards inside — but to keep the retro look, there’s an old-school toggle switch for power.
Another thing I really like about this project is that we take some off-the-shelf maker kit work and apply it to a gift from the past and make it new again.
Stereo 20W Class D Audio Amplifier – MAX9744: We like the MAX9744 amplifier at the heart of this board because its very easy to use, but it also has both analog and digital volume control capability. Use a single 1KΩ pot (we include one) to adjust volume analog-style. Or hook it up to your favorite microcontroller and send I2C commands to set 64-steps of volume amplification. Read more.
Electret Microphone Amplifier – MAX4466 with Adjustable Gain: Add an ear to your project with this well-designed electret microphone amplifier. This fully assembled and tested board comes with a 20-20KHz electret microphone soldered on. For the amplification, we use the Maxim MAX4466, an op-amp specifically designed for this delicate task! The amplifier has excellent power supply noise rejection, so this amplifier sounds really good and isn’t nearly as noisy or scratchy as other mic amp breakouts we’ve tried! Read more.
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