Greetings to the Cult of the 6 stringers:
Drop tuning. YES we mean tuning your guitar lower.
Is there a point? Yes,
Is it common? Yes.
Is it overused? ohhhhh yeah.
Myths of Drop-Tuning:
"but... but.. but... it sounds better, doesn't it?"
"all the cool metal bands do it, why shouldn't I"
To a degree it is tasteful. I have a hard time justify anything lower than C# standard. That is three semitones lower. For certain types of music (metal, which may be obvious), utilizes it quite often. Then you have the ass-clowns who tune to B standard, A standard, Drop G, etc.
I have an argument on two fronts:
First is that E2 which on a guitar is the low E string 82.41 Hz. What does that mean? Every second 82.41 sound waves pass any point (Hz is cycles per second). Simple.
HOWEVER the frequency scale is NOT LINEAR, it is logarithmic. E2 is 82.41 Hz (as we have already established) one octave lower E1 is 41.20 Hz etc. Which is what a bass is tuned to.
The threshold for the human ear is typically between 20Hz and 20kHz (twenty thousand hertz). So, you can only go so low. The bass typically drops with the guitar.
The guitar is definitionally a mid range instrument. SO what does that mean? You are changing the range. What happens if you tune your guitar to B standard? Your whole guitar is five semitones lower. It begins to encroach where the bass guitar is, the bass drop tunes as well. If you tune the guitar lower, where are the mid-range frequencies? Missing in action to a degree. So you have a hole in your mix, not a good thing.
The gear side. MOST modern guitar speakers (everything from Celestion Vintage 30's to Celestion Greenbacks, T75's, etc.) start to roll off their low end at around 100 Hz, give or take a bit. What does that mean? the speakers have a harder time producing lower frequencies. So 100Hz is about a G2, (third fret on the low E string if tuned in standard). That isn't a big deal.
Now lets go to the bastard child B standard tuning, ~61Hz. HUGE difference. The lower tuned notes cannot be as efficiently produced by the speakers, so you lose some lower frequencies. Lower, and you aren't fully hearing the fundamental harmonic, you are hearing other harmonics as well.
In summation, think before you drop. If you like it you like it, but now at least you are informed.
Thank you for your ever so valuable time,