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$
So a total of 52$ for a powerfull wireless speaker
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Passive 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.
Step 2: Active Speaker
As active speaker I select the FRS8 from visaton.
It is 8 Ohm speaker with 30W output.
They are full range speaker so no need of tweeter or woofer, they are effective from 200Hz to 20KHz.
I add the passive speaker to add some low frequency punch.
Step 3: Amplifier
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.
Step 4: Glue All Part Together
When I finish to glue the amp and the battery to the wood inside the box I start to glue all pieces of wood together.
For that I used wood glue and I did a wood paste made with glue and sowdust to hide default.
Step 5: Power Supply
To supply the amplifier I used a 12V 4800mA battery connect to the output of the bax by a jack glue to the inside box.
Step 6: Result
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 .