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M34_AudioBooks_Use6Titles

Don’t judge these books by their covers! They hide an amplifier, a speaker, and a plush compartment for your portable audio player.

Most amplifiers and speakers are flashy — shiny plastic and metal covered with lights, knobs, and indicators — and totally out of place in my reading room. I wanted a design with more warmth and feeling.

Nothing looks as perfect on a bookshelf as books. So the obvious solution was to put a speaker and an amplifier inside a book or three. Putting things in hollowed-out books is a trick as old as bookbinding, but with a little more effort we can even disguise some of the controls in a natural way, such as using a tasseled bookmark as the volume control.

The hidden speaker uses the covers of 3 books to disguise its true nature, with wooden frames providing stability and durability. A muslin cover allows the sound to escape unmuffled while keeping the look of paper. The electronics are based on a commercial amplifier kit that we modify slightly to move some of the components to more useful locations. A padded nook provides a safe place to keep a music player or radio.

Steps

Step #1: Prepare the books.

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  • Find 3 hardbound books that are each at least 1¼" thick and 5½" wide. They work best if they’re all the same height; 5-3/4"×8-1/2" is a common size that will hold everything we need.
  • TIP: Stores and library sales are good places to buy gently used books. Try to find books that look good without their slipcovers and that you won’t mind displaying on your bookshelf.
  • Decide on an order in which to shelve the books. The book on the left will hold half the speaker, the center book will hold the other half of the speaker and the power switch, and the right book will hold the amplifier and storage for a music player.
  • Remove each cover from its pages by opening the front cover and folding it back. Use a sharp blade to carefully cut along the joint between the cover and the bound pages.
  • TIP: If you want to keep the pages you can rebind them. See “Olde-School Bookbinding” in MAKE Volume 05.

Step #2: Build the support frames.

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  • Each book cover is supported by a 4-piece frame. Since your books are probably slightly different thicknesses, measure the width, depth, and height of the pages removed in Step 1 to get the dimensions for the frame for each book. Make paper patterns for each side, being sure to mark each piece with the book it belongs to (right, center, left), what part of the frame it is (top, bottom, edge, spine), and which direction it goes.
  • The righthand book has an internal compartment to cover the amplifier board. Cut two more patterns — a “cover” and a “divider” — for the panels that will form this compartment. The cover should be 3" long, and the divider should be as long as the book is thick, minus one plywood thickness. Each should be just wide enough to fit snugly inside the frame.
  • Download the cutting template and use it to add cutouts to the patterns for plugs, peakers, etc.
  • Cut all the pieces from ¼" plywood following your patterns. Miter the short edges of the frame pieces at 45°, so they fit together at the corners like a picture frame. Be sure to mark each piece, following its pattern, with its position and orientation in the finished frame. Test the pieces for fit, and then use a drill and a jigsaw or coping saw to remove the cutouts
  • Assemble the frames with wood glue and clamps. Use a combination square to keep the corners true and wait for the glue to dry before removing the clamps.

Step #3: Build the support frames (cont'd).

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  • For each frame cut a strip of muslin 3" wide and 3' long. Iron out any wrinkles. Glue a single strip of muslin to the outside top, edge, and bottom of the frame. Use white glue, on the inside edge of the frame only, and work slowly around the frame to prevent wrinkles, using pushpins or thumbtacks to hold the fabric in place while the glue dries.
  • Use a craft knife to cut an “x” in the cloth over the volume knob cutout. Fold and glue the tabs of cloth inside the hole. After all the glue has dried use scissors to remove any extra bits of cloth from the inside of the frames. If you’re making a wall-powered amplifier, repeat the process with the hole for the DC jack. Your finished support frames should look like step photo 3

Step #4: Build the amplifier and cut the covers.

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  • Assemble the amplifier kit according to the instructions, but do not solder the stereo jack, DC jack, or speaker output screw terminal.
  • Solder 10" of 22-gauge wire to the PCB at the DC+ and – connections, both OUT connections, and each of three INPUT connections. Use different colors so you can easily tell them apart.
  • Use a sharp craft knife to cut holes in the covers following the downloaded template.

Step #5: Assemble.

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  • Attach each frame to the back cover of its book with epoxy. Again, take care not to let the epoxy get on the outside cloth.
  • Position the power switch, speaker, and amplifier. Route the wires and solder them in place. The speaker wires are not polarized and can be connected either way to amp OUT.

Step #6: Assemble (cont'd).

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  • Wire the stereo TRS plug.
    • Solder the INPUT ground wire to the plug sleeve, as seen in step photo 1.
    • Solder the INPUT wire next to C5 to the plug tip.
    • Solder the remaining INPUT wire to the plug ring.
  • Wire the power switch.
    For wall power:
    • Install the power jack in the matching hole in the frame.
    • Connect the center pin of the power jack to one side of the power switch.
    • Connect the other side of the power switch to DC+.
    • Connect the outer ring of the power jack to DC–.
    For battery power:
    • Connect the red wire from a 9V battery connector to one side of the power switch. You might need to add extra wire so it can reach.
    • Connect the other side of the power switch to DC+.
    • Connect the black wire from the battery connector to DC–.

Step #7: Assemble (cont'd).

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  • When all the connections are complete, connect power and a sound source to be sure everything works correctly.
  • Use epoxy to join the 3 books cover-to- cover. Epoxy the frame of the lefthand book to its back cover. Use a thin bead of epoxy around the rim of the speaker to fasten it in place in the left and center books.
  • Secure the amplifier in the righthand book using the bolt and nut supplied with the amplifier kit. Use more epoxy to join the center book’s front cover to its frame.
  • Fasten the amp cover and divider pieces in place with wood glue and clamp until dry.

Step #8: Finishing touches.

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  • Using your own measurements and the pattern, cut a piece of velvet to fit inside the audio player compartment and to cover the amplifier compartment. Stitch or glue the seams, and use white glue to fasten it in place.
  • Place a small amount of epoxy into the edges and top of the volume post, wrap the tassel around the knob, and secure with a knot.
  • Place the finished boombox on your bookshelf or end table, plug in the AC adapter (or clip on a 9V battery), connect the stereo TRS plug to the headphone jack of your favorite portable music player, and you’re ready to listen.

Steve Hoefer

Steve Hoefer is a creative swashbuckler, freelance writer and inventor. He regularly contributes projects to the pages of MAKE and his inventions have appeared internationally on TV, radio, and print. He lives on his family farm in Iowa.


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