Corner base trap- to the ceiling?

Given how long are bass frequency waves, the pressure of the soundwave is highest at a boundary because the positive pressure of the wave moving toward the wall meets the positive pressure of the wave reflected back from the wall (the incoming and reflected back portion of the wave is still more or less in phase).  A corner has two such boundaries making it the best place to put devices.  Hence, a corner is the best location for a device trying to attenuate lower frequencies, but, people do tend to expect greater results than they deliver.

But, even quite large diameter traps are not that effective at very low frequencies, so that they don't do much below 60 hz or so.  Still, they do tend to smooth out bass response to some degree.  The ASC tube traps have one side that is designed to reflect and scatter higher frequencies (act as diffusor), and one can thereby orient the traps to either absorb and dissipate higher frequencies or reflect that energy back into the room.  You can experiment to determine which is better for your setup.

@bigtwin , didn't mean to trigger anyone, just expressing my opinion. I followed Acoustic Fields for a while, but didn't find it useful in the end. I'm sure his consulting service has tuned many rooms successfully. I use the approach of measuring my setup with REW, and using a combination of pressure and velocity absorption, multiple subs tuned with DSP, and room setup to tame low frequency response. To each their own.

There are accusations of Foley's less than altruistic behavior on other audio forums, if interested.