Need help with High Pass Filter Design

Hey,

I've been working on a University Project and have hit a bit of a snag, so I thought here might be a good place to ask for help since I have heard that HeadFi has a lot of people making their own Amps and stuff.

Basically, the idea of the circuit is to have a stereo input from a 3.5mm jack, and each signal is passed through a High Pass filter (or treble booster), and then a Low Pass filter (bass booster) and then finally amplified with a non-inverting op-amp configuration before output. The signal will be some Music from someone's PMP.

The problem comes from the High-Pass Filter. A want the filter to remain at Unity Gain all the way up until 10kHz, at which point the Gain increases as sharply as possible to around 5ish.. maybe 10, and then remains there. This is my Circuit Diagram:

How it works is that as the frequency of the input increases, the Reactance (Xc) of the Capacitor decreases. At large values of Xc, when the frequencies are low, the combined impedance of the Capacitor and resistor in series equates to roughly 1M, and so the Gain is more or less Unity, or at least not too high (important because I don't want to lose the lower frequencies, I just want to leave them be)... And as the frequency increases, the reactance decreases, and that combined impedance drops, so the Gain increases... and as the impedance drops to a very small, negligible value that 200k resistor keeps the Gain at no more than 5.

Now, when I test the circuit, it's all fine.. it's Small/Unity Gain up until 10kHz, at which point it begins to increase. The problem arises here, the Gain just isn't increasing quickly enough... It takes up to well over 100kHz to reach my maximum, and we know that those frequencies won't even be in the signal, never mind audible. Obviously, the reactance of the capacitor is not decreasing quickly enough with the change in frequency, and I need a way to make it decrease as sharply as possible once it has dropped to what is effectively 0ohm, I don't care how much farther it goes, I just need it to drop really quickly.

Then again, maybe I don't understand this circuit as well as I think I do.

So, if you have taken the time to read all this, then thank you and do you have any ideas for a solution? This really has me stumped.

Yeah, thanks.

I found a solution. I cascaded two of those circuits in series and that brought the roll off up to an acceptable rate.