This is how you fatten up a kick drum without adding any EQ:
Make either a 52Hz or 60Hz sine wave at about -6dB on an audio track with a signal generator.
Send the kick out to a bus prefader at 0dB.
Now put a gate on the Sine wave and have it be keyed by the bus.
Adjust the settings so that the tone peaks through as tight as needed.
Play around with minor adjustments to get a perfect sounding kick.