I share a similar experience. Tried the "crawling" method trying to find a good placement for the sub according to what I could hear. But I could never find a location for the sub that sounded good in the listening position. This method may work well in some cases, but not in my room at least. Maybe it works better with multiple subs?
Anyway, I took another approach. As my room suffers from room modes along the listening path and especially at one frequency around 31 Hz, I decided to try to cancel out a high pressure area caused by this room resonance. I used a sinus generator that is a part of the RAW audio measurement PC software to generate a 31 Hz sinus signal. Connected the Laptop to a USB DAC, amplifier and speakers. I found a high pressure area just few feet behind the listening position. I placed the sub there. Then I listened at this location of the sub and fine-tuned its position, level and phase so that the sound pressure in this position was similar to other non-resonant frequencies. The possibility to fine-tune the phase of the sub was an important feature to be able to cancel out the pressure. I should add that I use floor standing speakers that goes down to about 27Hz -3dB.
Finally, I got good base in my listening position without using any bass traps (tried that before with minor success). Later I verified the frequency response in the listening position using a measurement mic and again the RAW software. The frequency response in the lower end looked really good with the sub and the settings I have made by this method.
Anyway, I took another approach. As my room suffers from room modes along the listening path and especially at one frequency around 31 Hz, I decided to try to cancel out a high pressure area caused by this room resonance. I used a sinus generator that is a part of the RAW audio measurement PC software to generate a 31 Hz sinus signal. Connected the Laptop to a USB DAC, amplifier and speakers. I found a high pressure area just few feet behind the listening position. I placed the sub there. Then I listened at this location of the sub and fine-tuned its position, level and phase so that the sound pressure in this position was similar to other non-resonant frequencies. The possibility to fine-tune the phase of the sub was an important feature to be able to cancel out the pressure. I should add that I use floor standing speakers that goes down to about 27Hz -3dB.
Finally, I got good base in my listening position without using any bass traps (tried that before with minor success). Later I verified the frequency response in the listening position using a measurement mic and again the RAW software. The frequency response in the lower end looked really good with the sub and the settings I have made by this method.