Hello friends. My question is how to create a speaker level to line level converter for audio. The twist on it is the speaker is driven by a bridged amplifier, i.e. both terminals of the speaker are active and neither is tied to ground. If it were a regular speaker I could have the choice of either just a simple voltage divider with resistors or else use `an inverting op amp as an attenuator. But all he designs I have seen for either assume the (-) terminal is tied to ground, which in this case it is not. It is low wattage maybe 10 watts per channel into 8 ohm speakers.
I was thinking maybe use a 1:1 600 ohm audio transformer, connect the speaker terminals to the primary side, and then secondary taps would mirror the speaker voltage but be electrically isolated from the amplifier, and I could tie one lead to ground and the other lead be signal. Then it could go into an op amp attenuator or just a voltage divider. It seems like it would work, but will it? The #1 concern is to not fry the amplifier. The line level signal from L and R channels would be mixed down to mono and will be low pass filtered then sent to a subwoofer amplifier, so I am not concerned about the high frequency audio, just going to filter all of that out anyway.
Thank you in advance.