Band Pass Filter for musical note separation
Those are technically second-order filters, but because they're band-pass, it's like a first-order high-pass combined with a first-order low-pass; your filter just doesn't roll off fast enough as you move past the "cutoff" frequencies.

A filter order like that might be ok for a crossover network, where you can accept a fair bit of energy past the cutoff frequency, or a hypothetical application where you wanted to separate a 100 Hz tone from a 10,000 Hz tone, but for tones as close to each other as 941 and 1,026 Hz, you need a much steeper rolloff, which is going to mean a higher order filter.  Also keep in mind as you increase the order that filter coefficients producing steeper gain rolloffs for the same filter order (say, a Chebyshev as opposed to a Butterworth or Bessel) tend to have more ripple in the pass-band, which can also make separation of nearby tones worse.

As loudnoises has mentioned, high-order filter implementation is often done in software (via DSP) as it is often easier to implement the math for, say, a 12-th order filter than it is to deal with all the parts for a 12th order physical device.

If you just want to "try out" some other potential hardware designs anyway, Texas Instruments had a free tool to recommend values and show performance once values were selected, but it looks different than it did the last time I used it.