Not my preferred method but one that I experimented with a while ago (successfully I might say) is this:
Personally, I do not so much like the OTA solution because of the very low voltages (about 50mV) you have to bring your input high amplitude signal to (normally this may be up to 5V which is 100 times more!) before feeding them to the OTA the result of which you have to crank up again afterwards. This is bound to introduce noise into the circuit.
If you are looking for alternatives to the 13700-and-such-like-approach you may be interested in taking a peak at the NE570 and TDA1524.