I have a BLX2/SM58 that I use for presentations. Sounds great as long as the person speaking holds it a few inches away from their mouth like a singer would. I need to be able to pick up the voice (non singing) with the mic about 12 inches away from the mouth. Do you have a head available that I can replace the SM58 with that would help solve my problem?
Sorry, there is no solution to the problem, because it is a law of physics, not an improper mic element.
The SM58 element does not operate different at 12 inches versus one inch - it is the acoustical level of the person's voice that drops. This is called the inverse square law:
The difference in output level between 1 inch and 12 inches is huge: nearly 22 dB. The mic element will not change this.
You can try a different mic element that will sound differently, like the RPW114 (SM86 mic element), but the effect of the inverse square law is the same.