Supposedly this circuit is supposed to be a bass frequency booster.
I've been using this article as a reference, although the circuit they analyze is a different layout than mine.
I apologize if my work is hard to read or follow, but I'm getting something in a (1 - BPF) form for a transfer function (I struggled to get this into anything slightly resembling standard form, so there may be some calculation errors).
This looks like a notch filter to me, rather than a boost.
A bridged-T feedback network is basically a low-pass filter mixed with a high-pass filter. It's usually a passive filter that creates a notch (cuts the frequencies) but when it's in a feedback loop it becomes a boost.
But I'm not seeing why or how that's the case. They also link to a site with the same T-network form that has the transfer function in a different form than I have mine in, but also concludes that it's a notch filter.
Is someone able to help me understand why the feedback network turns this notch into a boost?