Last year I bought a TaoTronics TT-BR06 Bluetooth Receiver to use with my iPhone. It works great, and the sound quality is fine. The only issue was that the volume was too loud. I am using it with a pair of Sony XBA-N3 earphone, it was uncomfortably loud even on the lowest volume.
Recently I looked up for this product on Amazon, and I found a review that mentions a modification that can adjust its output gain. I tried it and it worked like a charm. So I’m documenting this mod here. Maybe it also applies to other similar brands of Bluetooth receivers. So if you have similar problems, you can have a try.
The TT-BR06 uses a PAM8908 amplifier IC. The output gain can be set by two sets of jumpers. This work requires some basic soldering skills.
First I need to open the case. Both the front and the back panel need to be removed. I just used my nail and worked the way around the edge, they came off pretty easily. Then I took the PCB completely out of the middle frame, to make sure the soldering work does not damage the plastic case.
After seeing the PCB, we can find the PAM8908 chip on the front side. By reading the datasheet, we can know that pin 6 and 7 are the ones controls the output gain. The product is shipped with jumpers soldered to pads of R14 and R16 which sets the gain to +3db. We can change the gain to -6db by grounding the G0 and G1, which means we should desolder the jumper on R16 and soldering it to the pads labeled R13.
The process can be done by using a regular soldering iron and a pair of thin tweezers. It needs some patience to finish the work. Here is what it looks like when its done.
After the mod, the volume was effectively reduced, and the sound quality was not affected. Problem solved!
Wow! This is so cool!