I have this old BO speaker that's built like a tank, but what good is it when it does not connect to anything. I was going to throw it out, but had one more idea for it.
So I got this Bluetooth amp module from eBay:
TPA3118 2X30W Bluetooth Digital Power Amplifier for Modified Bluetooth Speaker
The DIY mod:
- Open the speaker enclosure
- Uninstall the crossover board
- Connect the woofer to the module's right channel output
- Connect the mid-range and tweeter (in parallel) to the left channel output
- Drill a hole for the power cable and push it through
- Attach the module to the inside cover of the speaker enclosure with tape
- Close it up
Currently the system is powered by 4x 18650 lithium battery pack that sits on the outside -- it lasts for about a day before needing a recharge). The audio signal connects via Bluetooth.
When it powers up, a voice prompt (in a Chinese accent) asks to pair, and then says that it's connected.
At minimum volume the sound can be quite hissy. The only volume control is via the source device, so I assume that the module is set to maximum preamp volume, hence the hiss. I am yet to try the 3.5mm input and test the hiss, but at low priority.
Later, I upgraded the battery holder to a single four pack, which looks a bit more tidy.
- The amp module suffered catastrophic failure during an incident when I accidentally connected a battery with reversed polarity at the power terminals. There was smoke and some of the speaker wadding got burned, but I managed to pull the plug quickly enough to limit the damage.
- In the coming months the amp and the battery were upgraded.
- It was found that connecting via an analogue cable instead of Bluetooth produces far superior sound quality by way of a much better performance in the high frequencies. Hence no more Bluetooth for now.