active filters: which resistors to buy

[peranders]

.... so I think we can agree on that this is a design equation.

Noise, distortion due to heavy load, stray capacitance effects, size of caps, availability of caps, drive capability of the active device, cost etc. All things must match. There are also different requirements for different frequency bands.

[RCBandwidth]

Hi:Your first step in designing your filter circuit is to determine your crossover frequencies.Step two is to pick a capacitor value and run some initial calculations to determine appropriate resistor values based on your capacitor value.It is far easier to adjust resistor values than it is to try to find an exact capacitor value to achieve your target crossover point.I would strive for a 1% tolerance on your capacitors,you can hand match 5% resistors if you have to keep the cost down.It is certainly true that larger values of resistors can increase noise levels in a circuit,most engineers will tell you this.I would encourage you to test your filter with a sweep generator and plot the response if possible.
Good luck...