# Speaker to line level circuit and values needed please

First post, so please go gentle.
I am simply looking to take a digital, mono amplified speaker signal (3w @4 ohms at 5v) and feed a Bluetooth transmitter, so I need to make sure I don't mismatch signal/voltage levels. Also, the speaker or Bluetooth option would probably be switchable.

Would someone more adept than I be able to scribble something up that would show me the correct circuit, resistors and values? Something along the lines of this, but the values aren't appropriate.

Some additional info I was given:

1. There is no "speaker gnd". Both sides of the speaker connection go up and down. That may or not matter depending on what you're plugging in to though. The solution is simple: isolation capacitors
2. The amplifier is class D. That means that the output from the amplifier is digital and it needs something to smooth out the signal. Normally this happens inside the speaker itself. In your circuit you would need to have a coil or a capacitor to smooth out the output the right amount.

So does anyone know how to set this up? I found some posts on here that were close, but I do not have a big Home Theater amplifier here, just this little output on a small Arduino based sound board.

These are the amp and transmitter in question. I appreciate any help at all, thanks.
Amplifier Blutooth Transmitter

• There is no "speaker gnd" ... gnd is just a reference point that you choose ... the negative probe of the voltmeter or the ground probe of an isolated oscilloscope would usually connect to that reference point – jsotola Apr 7 at 3:31