Friday, 14 July 2017

Make a Portable Speaker with PAM8403 Amplifier

Make a Portable Speaker with PAM8403 Amplifier - Intro


Do you have an old speaker or two hanging around in the garage or loft? Would you like to make a kick @$$ portable speaker for just £3 / $6? Left me show you how.

Lets get real here, you are not going to save lots of money you can probably buy a portable speaker, for you iphone or android phone direct from china for £6 / $12, but this way you get to save a trip to the dump, and get some satisfaction.

Old Speaker + £3 = Disco


Make a Portable Speaker with PAM8403 Amplifier - Ingredients


You will need the following ingredients:


  • An old speaker (4, 6 or 8 ohm) lower ohms = more volume.
  • Some wire (door bell, lead from old adaptor. . . )
  • Battery Holder to hold 3 x AA or 3x AAA batteries  
  • PAM8403 amplifier board
  • A drill 
  • screw driver
  • Soldering iron
  • solder
I have gone in to detail regarding the battery holder and the PAM8403 amplifier below.


Make a Portable Speaker with PAM8403 Amplifier - The Amplifier


You can buy the vanilla PAM8403 board on ebay for next to nothing but for a few £/$ more you could get hold of a blue tooth variant. This is useful if you want to use a phone without the 3.5mm jack socket.

There also variants with a volume control, and a smoothing capacitor. This may be worth getting if you do not have a spare capacitor

Bluetooth . . . . . volume control . . . . . or vanilla (normal) the choice to yours.

Make a Portable Speaker with PAM8403 Amplifier - Power Source


The amplifier run on a any voltage between 2.5V and 5.0V. This means you can power it with:


  • 3 x AA batteries
  • 3 x AAA batteries
  • USB power lead from PC or Wall Adaptor
  • 1 x 18650 Battery
  • A USB power bank
I have tried with a USB power lead, and then 3 x AA batteries both worked very well. 

The amp have two channels (left and right) and as far as I know you have to use both channels. You cannot splice the two channels together to make one. 

Make a Portable Speaker with PAM8403 Amplifier - How To

So the old speaker I have had a tweeter (small high frequency speaker) and woofer / midrange speaker. I used one "channel" from the amop for each. I cant remember which way around I put them. 

You will need to remove the cross over if there is one, save the capacitors for re-use.


In order to do this you will need to open up the speaker and, take a wire from either the woofer or the tweeter, you may find that you have a cross over unit in there, you will need to by-pass this so you can create two separate channels. Keep the cross over and carefully remove one of the capacitors for reuse, in a moment. You will need to solder this in to the positive wire of the tweeter. Like this:

Adding a capacitor as above will improve sound quality.

I first tried the amp and speaker together without this capacitor and the tweeter sounded distorted. However, after adding the capacitor all was well. 

The amplifier is tiny. . . note pinky (little finger) for scale.



Next up we need to start soldering all the bits together, if you do not have a soldering iron just buy one. They are useful for all sort of mending and fixing and making. As you can see the PAM8403 amplifier is tiny. And this makes for fiddly soldering, you can only use thin wire as the holes are too small for thick wire. 

Wiring is simple. . .but fiddly!


So for simplicity I house the wiring in a surface mounted junction box on the rear of the seapker, I had one of these spare in the garage. But you could actually just put all of the wires inside the speaker if you wanted to. Although it would be more fiddly to work on. 

3 x AA Battery Holder - £1.99


This cheap battery holder from ebay has a built in switch (counter sunk). I screwed it on to the rear of the speaker. With 3xAA batteries in side in produced 4.5V, good quality rechargeable batteries are preferable to disposable, as they hold a higher charge for longer, so voltage stays are close to the optimum (5V) as possible. 


Toggle switch. . . if you like.


I also added a toggle switch that I had as it is a nicer switch to use, than the one on the battery holder. You can also use a piece of cord, rope or strapping as a carry handle. 

Carry Handle


Make a Portable Speaker with PAM8403 Amplifier - Performance 


The sound level of the finished speaker (4 ohms / 4.5V ) is approximately 60 - 70 decibels. You cannot really have a normal conversation in the same room. As a 35+ year old man, I find it unpleasantly load at full volume.

There is quite a lot of midrange and high pitch sound, and perhaps some more bass would be a good, but overall for a piece of hardware that cost 99p, and is the size or a postage stamp it is amazing . . almost alchemy in terms of its performance. 

This is a fun, low cost project that I have enjoyed doing, and I would urge you to do the same if you require a speaker of this type rather than buying some other hard to recycle item from china.


Environmental Permit Applications

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