Introduction: Sound Bar

By Blog

Hi All,
I have a plasma TV, which has decent sound quality 15W, but with kids making noise, it is difficult to listen...

I needed a sound bar to amplify my TV's sound level with digital-optical audio in. but only available in high end and expensive sound bars

The entry level soundbar have just 15W output, which is too less for my requirement

Inspiration came from my dad, he had few old Car speakers (20W) lying around, which he wanted to throw. So thought to use them and make a sound bar for myself

In this instructable, will share how i made it, Please share your comments

Features

  • 100W output (90db)
  • 180w coaxial speakers with tweeters
  • Bluetooth 4.0
  • Fibre audio / coaxial in
  • RCA audio in
  • USB 5 volts regulated power for charging phone while playing
  • Button controls
  • Bass tubes
  • Strong plywood frame
  • Equaliser graphics is just for show

Step 1: Design

  • I am using TDA7492 class D 50W+50W amplifier with built in bluetooth 4.0 and Aux in.
  • The Amplifier is powered using old laptop charger.
  • OUtput connecter to 2 speakers
  • Aux is connected to RCA audio ( to be mounted on rear side) in via 3.5MM stereo
  • To this RCA Audio I will connect my Optical audio to Analog converter
  • To power Digital to Analog convertor, I am using LM2596 to step down to 5V
  • Also using a USB type 2.0 as 5V out, This can be used to charge mobile phone during bluetooth playtime

Step 2: What Do We Need ?

Material

  • 15 mm plywood
  • 6 mm plywood
  • wooden dowel
  • TDA7492 50+50W/ Bluetooth 4.0, Aux In CLass D amp
  • Bluepunkt IC 402 180W Coaxial speakers with tweeters
  • Old laptop charger
  • 3.5 mm audio cable
  • RCA female connector for surface mount
  • Usb female type 2.0 for surface mount
  • Switch
  • LM2576 DC - DC step down 3A ( Adjusted to 5V)
  • Optical audio to Analogy converter
  • RCA audio cable


Tools

  • wood saw
  • Dremel with 2mm drill bit
  • Hammer
  • screws
  • fevicol
  • glue gun
  • Cable tie
  • black oil paint
  • Sand paper

Step 3: The Frame

To make the frame cut 15 mm plywood

  • 431.8 mm x 114.3 mm - 2 pieces
  • 95.2 mm x 114.3 mm - 2 pieces

Front panel and back panel is 6mm Ply wood

  • 114.3 mm x 431.8 mm - 2 pieces

Use the template supplied by manufacturer to drill/ cut out a hole to fit speakers. I used dremel to drill holes and then chisel to cut. To smoothen the hole I used 80 grit sandpaper

Glue all sides and front panel using PVA glue or fevicol, leave it overnight to dry. Remember to seal all gaps using glue and saw dust.

Add wooden strips (5mm) on the back side that will hold the back panel.

Using Sandpaper 80, 150 then 220 grit, smoothen the surface and paint it based on your choice. I used black oil paint, this gives shine to the frame...

Step 4: Back Panel

For the back panel we need make holes for

  • 220V cable entry
  • RCA audio in
  • USB connector
  • A switch
  • Bass Tubes

Bass Tubes : I used electric conduct pipe 25.4 mm diameter as bass tube with 63 mm as leght

I used hot glue to fix all component into place. May need to add supports as needed

Step 5: Control Buttons

On my TDA7492, i have Play/ Volume buttons which I wanted to use.

I needed a design buttons which

  • 30 mm in length
  • Stay in aligned with the front panel holes and buttons
  • Does not fall off when inverted

With few days of thinking I came up with the design.

  • I am using a small PVC sheet to keep the wooden dowels in aligned position with front panel
  • Using two cable ties to hold the dowels in place

I have shown a closeup in the image

Step 6: Power Supply

I had this old laptop charger with damaged output cable.

  • I broke open the charger
  • Connected AC in directly
  • Connected DC out to 5.5 Power plug with short cable length
  • Connected DC out to Step Down LM2576 module
  • Adjust the output of LM2576 to 5V

Test everything

Step 7: Bringing All Together

  • Used an old 3.5 mm stereo audio to connect to surface mounted RCA in
  • Fix the power supply using double sided tape
  • Using hot glue gun, fix, USB, RCA ,switch and BAss tubes
  • Fix LM2576 using double sided tape

Test the USB output to be 5V and RCA In

Close the back panel using screws at distance that will ensure there is no sound leaks

Step 8: Enjoy

Connect it to your TV and enjoy the sound level. Mine gives about 90 DB output at 1 meter distance

Happy with the output.

Future Improvements

  • LED Graphic equalizer could be added
  • Remote control

Hope you like this project. Please share your comments