Arduino simple speaker connection

I have been using a very small speaker salvage from old earphones, as you will expect the volume in those are very low.

I didn't have a buzzer or a bigger speaker, but some transistors and resistor, so I did this impossible simpler amplifier.

I still testing it, some people said that there will be to much DC through the speaker. I will try it for a few weeks and see what happen.

Probably for my next project I will try some a little better like this: