everyone's voice will have it's own timbre and some will be raspy and some won't- if you are singing properly, the rasp should not be there as proper singing should come from the abdomen primarily. For any old guys like me, remember Steve Martin's tirade about singing from the diaphragm (I mean that's DISGUSTING!) Lol- my bad- anyway, you can make your voice raspy by smoking, etc... generally though, the rasp and cracking and all of that is the result of singing from the throat and not from the abdomen and also tends to make you go flat if you try to hold notes (not enough air in the ol' lungs) for a long period of time.
Hope that's kinda at least a tiny bit helpful!
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