Increasing power of PAM8403 3W+3W amplifier board

[Wilfrid]

Amplifier board is 3W + 3W PAM8403 (datasheet) class D.
I've a few speakers 4Ohms 5W

As I'm not familiar with class D.
So to have more power in a large place, not to have something very loud but having a good repartition, can I:
- Use 1 amplifier, left + right to the same speaker, and so using a second amplifier left + right for a second speaker? By simply soldering left and right input together.
- Or using 4 speakers (Parallel? Serial?) and doing the same bridge mixing L+R outputs.
- Or do I have to use 2 amplifier boards and 4 speakers, but wiring from left to left and right to right, (so in my case having a certain lenght of wiring which seems not to be too good)... and adding 2 lefts input together, and 2 right inputs together.
...And to go further, can I use 8 or 16 speakers connected to 4? 8? PAM8403 to have a nice repartition of sound in a large place.
Any professionnal suggestion is welcome, and I hope you'll understand my french accent
After that a little operation on how to multiply and add all these Watts, Volts, and Ohms is also welcome to choose my 5V DC power In

 

[Dinithm]

An externally hosted image should be here but it was not working when we last tested it.

 

[abraxalito]

Since these little puppies are so cheap on Taobao (1.2rmb or around $0.20) I've also given the issue of increasing the power some thought. I only came up with using output transformers. Your output power is limited by the voltage swing, so you need a trafo to step-up the voltage. If you wind your own trafo you can dedicate a primary winding to each amp, then choose the appropriate number of secondary turns. So for example with 4 primary windings each driven by an amp you could arrange the secondary to deliver 12W (minus a small loss due to the trafo's resistance).

 

[Wilfrid]

Thank you for the answer... And this nice drawing that makes things very clear.
I'm gonna try it like this.
This means:
- No problem to split the input and send it to that many devices?
- No problem to bridge Right and Left input on each PAM8403?
(Because people say that it's not something good on a class D amplifier)
- Each PCB PAM8403 becomes here a mono amplifier?
- Speakers stay in 4 Ohms?
- DC supply to use in this case should be 5V / 36W ?

 

[lutkeveld]

No you can't bridge them, you can parallel them. Bundle left and right respectively and connect them to the speaker. Then you have one channel that can deliver 6W in 2 ohm.

Supply can be 5V 1.25A (6,25W).

 

[counter culture]

You could use them in an active speaker system. Biamping or triamping. This radically increases the effective power, 2*3W amplifiers can have an effective power of 12W if used for biamping. Or maybe drive a line array?