I tend to agree with Temple--the word 'cackle' brings to mind a shrill, high-pitched sound. That defeats the author's intent to portray a character's deep voice.
Of course, I checked my favorite internet thesaurus and found no synonym for 'cackle' that wound convey danger--they just got shriller and sillier. Most used phrases like 'evil laugh.' You could try something like 'menacing laughter,' or you could go with 'malevolent,' 'wicked,' 'murderous,' etc.
I would change 'cackle' for another word/ phrase, since there's no guarantee the reader will visualize Vincent Price or the Emperor from Star Wars.
[As for Vincent Price, I always thought he had a rather high-pitched voice for such a big man. And his laughter didn't always convey evil--he was a straight actor, sometimes a romantic lead, long before he became the curator of the House of Wax. And no, I'm not that old, but my mom talked about him all the time.]
JP