Quote Originally Posted by deeaa View Post
One thing that can have an unbelievably strong effect is also wall proximity, both behind the amp and in front. Bass waves have such a long wavelength that they literally aren't audible in spaces smaller than the frequency demands. Also guitar amps, particularly open-backed Fenders etc. can sound drastically different when placed against a wall/in a corner; especially crunchy sounds can change totally. Battled with these issues a lot gigging in very small venues back in the day, both as a bassist and guitarist.
This is a common misconception. If it were true, then you wouldn't be able to hear any bass in headphones.

The idea that bass waves take space to develop is false. What actually happens is that in a certain point of a room you may get phase cancellations from room reflections leading to the false idea that more space is needed for the sound wave to "develop". The bass sound waves are fully developed right at the speaker.