Simple Hydrophone (2nd Circuit)

So, condensing microphones.. as it turns out, are not the same as the microphones I’m used to… They don’t work like a reverse speaker, but are in fact more like a variable capacitor… So… That explains why my circuits didn’t work, and that I now have to adapt my circuitry to adapt to this.

So, I started off with this:

Problem with this was that the capacitor charged up, then saturated…

You can see it charging up to ideal at around 2.5s, then it saturates and the output signal slowly diminishes  

To combat this I put a high value resistor across the cap, so it wouldn’t charge fully:

To be honest, I’ve no idea why it’s charging up like that, it should just block DC… I dunno… Maybe it’s the wrong way around