
My impression -- it's not an area I've played with much -- is that the
much-beloved NE567 is basically obsolete.  If you want to detect a 1kHz
tone, set a switched-capacitor filter chip to that frequency, feed your
input to it, and see if anything comes out the other end.  The NE567 was
what you used when good clean bandpass filters were hard to do; nowadays
they're easy, and the results are better.