I am wondering if there is any way for me to eliminate the DC offset present in this Class B amplifier circuit.
The circuit is to be used to amplify music for a subwoofer and, as I understand it, a DC voltage across the speaker is potentially harmful. I built and tried a physical circuit that was almost identical (I think the resistors were 10k) that did amplify sound well but shifted the speaker's cone a noticeable amount immediately (even when no sound was playing), indicating a DC offset. The problem might be easily solved with a dual-rail supply as the output would then be centered around 0V, however, that is not possible for me to add to this design; I intend to have this circuit run off of a 12V battery. I assume there is a clever way to use some basic component to traverse this issue, but I am unsure what it might be.
My first idea was a coupling capacitor, as is used in many amplifier output stages. However, the coupling capacitor only allows the AC signal past it, making the voltage across the speaker somewhere in the millivolt range meaning that the current will be in the milliamp range. I assume this is a result of this circuit being more of a current amplifier/impdeance converter. So, I'm pretty sure that using a coupling capacitor is not at all the correct solution here, but please let me know if I'm wrong in this respect.
At this point, as far as I can see, I must maintain the same current while not having that unfortunate DC offset. Does this require an isolating output transformer? Though I was previously unfamiliar with the concept, I think I understand how a transformer can be used to make the relative voltages across the speaker terminals favorable while not eliminating any of the actual power amplification that is desired.
Additionally, is this even an optimized class B amplifier? I've tried to play around with the values and this seems to give a pretty optimal amplification, but I am not too knowledgable when it comes to the specifics of this amplifier class.