Hello,
I did a bluetooth speaker with :
12V 4800mH battery 7$
2*50W TDA7492 amplifier with a bluetooth modul on it 10$
Two 3 pouces WOOX passives speaker 10$
Two active speaker visaton FRS8 30W 15$
Oak 10$
So a total of 52$ for a powerfull wireless speaker
.The back will be powered by two passive speaker to produce the low frequency.
They are screwable for the inside of the speaker so I did an extra deburring around the first 3 pouces hole.
Passive speaker are not powered so they move with the pressure of the active speaker.
To maximise this air transfer the box need to be hermetic, so the passives speakers are glue to the wood to avoid any loss of air.
The amplifier is 2*50W for a 24V supply but my battery is 12V so 2*25W max.
It is perfect to not blow up the speaker rated to 30W max each.
I replaced the X7R 1uF output capicitor by a plastic one to improve the distortion in high frequency.
I glue it to the passive part to reduce the vibration from the active speaker, on top of that I try to do a glue pillow to improve it.
As result soud is very good, enought power for an wireless speaker.
I try a 3/4 power during 5 hour before charge the battery.
The passive speaker are not the best but move with speaker, will try a better one next time.
I apply an oil o the wood nothing else after sans paper 80/120/180.
Hope you enjoy it .
Bye