Active crossover built into amp

[benproiii]

Is it possible to modify the nfb of a solid state amp to have a low pass filter at 200hz and another amp as a high pass to make 200hz and above. To remove the need for a opamp in the signal path.

[abraxalito]

The problem with this idea is stability. The usual filter topologies have a unity gain follower. You can get a chipamp stable in unity gain but you need some external components and its a little tricky to be sure you've got the right values. You'll also need a scope to check you got it right and there's no oscillation. The common mode input range of the chipamp should also be checked too as they're not designed to work with high common mode signals.

[benproiii]

That seems really hard to do, i built the dx precision i for the highs/mids and the dx turbo for the woofer. Is there any simple descrete active crossovers that dont distort or color the sound.

[twest820]

No, they're all minimum phase devices and hence introduce phase shifts. The same goes for your proposed bandpass feedback loop, however, so you might as well just throw some Sallen-Keys or a state variable filter in there with decent op amps and move on to running the source material through an inverse allpass or similar delay compensation---at 200Hz time reversed IIR is probably the best choice for that.

[abraxalito]

I've designed op-amp based XOs that don't colour the sound as far as I can hear. Had to use slightly non-standard methods, but you're welcome to the schematics which I've posted up already somewhere else. Or you could go digital in your XO which I'm convinced is the future for DIY because of the endless tweakability and shareability (of customizations).