I have an old stereo that I want to resurrect and add Bluetooth to it. For that, I bought a Bluetooth module, this one: https://www.aliexpress.com/item/PAM8403-Wireless-Stereo-Audio-Receiver-Module-For-Arduino-Digital-Amplifier-Sound-Loud-Board-Micro-USB-Bluetooth/32668159372.html?spm=a2g0s.9042311.0.0.7b634c4dWucCH7

The problem is when I try to connect it to my stereo. My stereo has a common ground for both the line in and the speakers, while the Bluetooth thing has different grounds for each channel.

I've tried to connect the speakers directly to the bluetooth thing, and it sounds fine, but when I short the grounds the music stops playing.

Is there any way I can connect that to my stereo?

  • 1
    \$\begingroup\$ You need to link to a datasheet for that device rather than the catalogue page. We need to know the pinout and device specification. Our advice is "No datasheet? No sale!" \$\endgroup\$
    – Transistor
    Commented Aug 26, 2018 at 8:40
  • \$\begingroup\$ I understand but I couldn't find it anywhere. Googleing for the number PAM8403 shows a different part ^^ \$\endgroup\$
    – George
    Commented Aug 26, 2018 at 9:34

1 Answer 1


use an audio isolating transformer

$5 at the auto-parts store.

  • \$\begingroup\$ I don't understand how the transformer works. Putting one on each channel and shooting the output grounds will work? \$\endgroup\$
    – George
    Commented Aug 26, 2018 at 9:38
  • \$\begingroup\$ yes, the device I suggest actually packs two transformers into a single packager, one for each channel. \$\endgroup\$ Commented Aug 26, 2018 at 9:58
  • \$\begingroup\$ I see, looks like a very clever solution, I definitely gonna try that. One last thing, will I experience some audio quality loss with it? \$\endgroup\$
    – George
    Commented Aug 26, 2018 at 10:29
  • \$\begingroup\$ there will be some loss, you probably will not notice it. \$\endgroup\$ Commented Aug 26, 2018 at 10:32

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