Need help with a notch filter.

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I’ve been playing around with some inexpensive 8” full range ceiling speakers. You know the type, stamped frame, small magnet, paper cone, cloth surround and a whizzer. They are primarily midrange, being a bit weak in the bass and somewhat thin in the higher frequencies. I won’t be using a transformer.
They do sound OK for public address and elevator music, but I’d like to contour the frequency response a bit to make them more acceptable for FM and stereo. I was thinking of attenuating the midrange by about 3dB from 200Hz/300Hz to 2KHz/3KHz depending on available component values, size and cost. The speakers are 8 ohms nominal, but I measured the resistance and it is 6.5 ohms DC, so I imagine that the impedance around 200Hz would be 6.5 - 7 ohms and then rising gradually from there.
I’m not sure what you call the filter, but I’m pretty sure it would be low Q and I’m not sure if you use the Geometric center frequency or the Arithmetic mean when designing such a filter. Anyone know what type of filter I should use, whether it should be series or parallel etc? What it is called and if there are any online calculators out there so I can massage the values.
Thanks.