This is going to be another quick tip for amp positioning.
Do you keep amplifiers on the floor while performing? If you answered yes, you’re not going to be projecting the sound in the best way, to yourself and the audience.
Think about it for a moment – the amplifiers are way down there, and your ears are way up on your head. Why would you point the amplifier in a direction other than where your (and the audience’s) ears are? Loudspeakers project sound in a very directional way. That means that the more you shift from being directly in front of the speaker, the greater the change in perceived tone. Try this experiment: Have an amplifier at head level, about two feet away from your face. Listen to some music in that position, then shift over by a foot to the left or right and notice the change in sound. Pretty noticeable, right?
The truth is in most situations, it’s near impossible to line up everyone’s ears to be directly in line with your amplifier speaker. You should, however, aim it in the general direction of your ears (and your audience’s) by tilting the amp or by getting it off the floor onto something closer to ear-level. A side benefit to doing this is that an amp will be decoupled from the floor which can help avoid low frequency resonances if you’re on a hollow stage.
This tip isn’t to say that this is the definitively CORRECT way of positioning an amp on stage. In some situations, you may only want the acoustic sound on stage. You would put the amp, therefore, in front of you to avoid hearing it. If a stage floor is elevated to the audience’s ear level, then placing it on the floor might be the best option. The goal is to figure out the optimal amp position for your given situation.
I hope this helps to get a better sound on your next gig!