Speaker to line level circuit and values

Community Chit Chat
1

Hi. First post, go gentle.

I am simply looking to take a mono amplified signal (3w @4 ohms at 5v)

and feed a Bluetooth transmitter, so I need to make sure I don’t mismatch signal/voltage levels.

If a voltage divider is the simplest fix, 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 (I don’t know if speaker GND is just the negative of spk + and - ?)

https://www.epanorama.net/circuits/speaker_to_line.gif

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

https://www.digikey.com/product-detail/ … ND/7603777

https://www.feasycom.com/tools/download … =en&id=166

2

You could try a bidirectional level translator, like our product here: https://www.sparkfun.com/products/12009. But a voltage divider could work too so long as the voltages are regulated to some extent.

3

Thanks for the reply.

Some more info from someone:

  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?