probably you know this, but it worked so well with me that ill emphasize it --
ive recorded all my songs in early morning -- my voice was lower toned, more bass , more deepness to it -- that is required in my type of songs .
oh ya.. and dont gargle, wash your mouth spit or caugh ( if possible) .. this way the wavelength will last longer
for me it lasts 2-3 hours ( this is the timeframe i try to record in , later on my voice crackels and gets tired anyway )
