Passive Cell Phone Audio Amplifier

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Project by FloridaArt posted 05-15-2016 04:04 PM 3387 views 4 times favorited 4 comments Add to Favorites Watch

May, 2016—One of the woodworking subscriptions I have sent along a project to make a sound amplifier for smartphones. I had no idea! So I Googled some keywords and discovered there are dozens of designs and techniques out there! To try my hand at this I took this blank, which was originally intended to be a band saw box with drawers, and decided to see if I could make a passive “boom box” for my smart phone.

This is the result, and I’m calling it my prototype. Good learning experience. Sound wise, it works fantastically! My friends are amazed to hear the before / after sound difference when inserting the bottom of my cell phone into the slot on the top. Wow! I made this specifically for my Motorola Droid Turbo 2, and have since discovered that it also works with two different sized iPhones.

The tricky part on this is making the slot on top after it’s all glued up. I used a small trim router and cut it without a pattern jig, so the slot is not perfect (see close-up photo). The back-rest hides the unevenness of the rear of the slot. More importantly that back-rest turned out to be a great idea to support the cell phone. Now that I’ve done this one I can think of some ways to do the slot with the band saw, prior to the sides going on.

Fun project!

-- Art | Bradenton, Florida

4 comments so far

View Woodknack's profile


12465 posts in 2619 days

#1 posted 05-15-2016 05:07 PM

Being a true horn shape it should be loud. How is the sound quality? Muddy, crisp, bassy, bright?

-- Rick M,

View oldnovice's profile


7380 posts in 3607 days

#2 posted 05-16-2016 12:52 AM

Wouldn’t be easier to get a hearing aid than to carry that around with you to hear your cell phone?

Nice simple yet effective design!

-- "I never met a board I didn't like!"

View majuvla's profile


13618 posts in 3106 days

#3 posted 05-16-2016 11:06 AM

I have to try this device once. Nice stripes.

-- Ivan, Croatia, Wooddicted

View Roger's profile


20965 posts in 3043 days

#4 posted 05-16-2016 01:07 PM

This is way nice. I’m sure it works gr8 to amplify the sound. Nothing at all with the way it looks.

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed.

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