Monday, 27 August 2018

TPA3116 2.1 Speaker Build

TPA3116 2.1 Speaker Build - Intro

This is a series of photos on the construction of a TPA3116 2.1 Channel Potable Speaker. The speaker uses wooden casing, up-cycled driver units, a 12v battery and can be adapted to run on main power also. If you would rather watch this on You Tube then please click here > TPA3116 Build Video

Finished Thing

TPA3116 is an amplifier, which runs on a variety of voltages. This "2.1" variant has stereo speaker out puts but also a third channel of sub-bass. This is my second build with this amplifier and it works well.

TPA3116 2.1 Speaker Build - Shopping List

For this project you will need the following. However, please do not be afraid to substitute materials, or even the amplifier board itself, for another model. For a smaller speaker you might try the PAM8610 which is a good little amplifier. For a very small speaker you might try the PAM8403.

I should also point out that if you are using recycled driver units, and they are still in the speaker case, why not re-use the case as well. You could glue, screw or bolts the two speaker together, and mount all wiring in side the speaker. This would avoid costs of buying wood.

For my speaker I used:

  • 12mm Shuttering Ply - Main cabinet / box
  • 9mm OSB (thin sheet wood - speaker grill support)
  • Screws
  • Two Part Filler
  • Paint (Optional)
  • Fabric or Cloth or Mesh
  • Amplifier Board
  • Speaker Cable
  • 12V to 24V boost convertor
  • Switch
  • 3.5mm jack cable
  • Driver Units
  • Insulation tape

  • Drill / Electric Screw Driver
  • Jig Saw
  • Tape Measure
  • Soldering Iron
  • Solder
  • Pencil

TPA3116 2.1 Speaker Build - Using Recycled Speakers

Making the box is perhaps the most demanding part of the whole project. As mentioned above perhaps re-use you speaker cabinets if you are recycling. I had some large sony speakers and the cabinets were fiar quality (not very weather proof though) and could have been bolted together, and used as is. 

Most speakers will have 2 or 3 driver units inside. 

Once you have removed the driver units from their original cabinet have a look on the rear of the speaker to try and figure out what ohm rating they have. For this project 4ohm speakers are best, but 8 ohm are OK, although the speaker will be quieter overall.

TPA3116 2.1 Speaker Build - Speaker Holes

You will need half a 4 x 8 sheet of ply to make this cabinet. Plywood is good, because you can get it wet, unlike MDF which swells when wet. Shuttering ply is a low garden water resistant ply, which can be sourced from most builders merchants.

Before you cut the panels, cut the holes for the speakers, it is easy to use a jig saw when the board is still in one piece.

Cut holes for driver units.

Try ou the driver units frequently to check fit. 
Do not make the mistake of drawing around the driver unit and then cutting, the hole need to be large enough that the screw holes sit on the wood.

Mark past inner edge of screw hole.
Rest the driver unit where the hole is intended, then mark the very inner most edge of the screw hole. Do this for all the screw holes. Then take away the driver units and join up the marks to make a cut circle.

Cut Line Smaller than Full Diameter

TPA3116 2.1 Speaker Build - The Cabinet

Once you have cut your speaker holes (for mounting driver units) you can continue with the rest of the cabinet. The front panel of the cabinet is the deciding factor in term of measurements for the rest of the cabinet / box. Take care cutting this panel, to ensure it is square.

Taking Shape

Cut the sides the same size as the front panel. Cut the top and bottom the same BUT 24mm wider to account for overall. Always cut bigger if you are unsure. You can always cut off excess with the jig saw although this results in a messy finish.

Blood, Sweat . . . but no Tears
Once the cabinet is complete you can paint it, and add a front mesh cover. This could be stapled in place or glued, or anything really. Just have fun choosing what ever you have laying around and do it!

Feet Made from Stiff Foam

Bass Port Doubles as Handle for Carrying

TPA3116 2.1 Speaker Build - Electronics

You could run this speaker on any number of different power supply's. I have compiled a list in a separate post: Power Supply Choices for TPA3116. I have also made some notes on the general performance of the TPA3116 amplifier board.

At 24V (max voltage) you are building a 40W amplifier. It is a class D amp, very efficient, so you get a lot of noise for those 40W RMS.

Hopefully your board came with a wiring diagram. This will show you which wire go in which clamps etc. Here I am running 2 x 8ohm speakers run paralleled to give 4 ohms.

Board Mounted on Steel Plate or Plastic Sheet Material
The board is supported using the 3 potentiometers, that control volume, treble, and bass. You could use the mounting holes also, but I find this unnecessary. 

A 12V battery feeds a 12V to 24V boot converter. This is better than 2 x 12V batterys, as 2 x 12V batteries linked in series can be 28V fresh off charge which is too many volts! 24V is maximum.

The power switch on the side of you build, should switch the BOOSTER on and off.

Externally, cut a neat hole, and then drill holes in this for RCA Sockets, Volume Knobs and Toggle Switch. Finally, you can add two protruding bolts, that can be used to charge the battery without opening the cabinet up every-time.

Not all TPA3116 2.1 boards are made equal, if you are driving 8 ohm speakers get a board with high "gain" (36db) as this will help with output.

TPA3116 2.1 Speaker Build - Conclusions

On completion you will have a loud speaker that give very good low bass sound. The cost can be a bit high, but for me this was becuase of the wood. I bought a 4' x 8' of plywood, why cost £40. But I still have over half left. . . . the battery would also be a significant cost.

Total cost disregarding these would be £20, with the added bonus that you can fix it when it breaks. You built it after-all. Oh! Its pretty heavy.

If you would rather watch this on You Tube then please click here > TPA3116 Build Video

Environmental Permit Applications

Desktop Study

Illustrator Devon

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