Yes, you can say that. It's a very creative way of describing someone's voice. I'm not sure if the 'charming' part works with 'magnetic,' but attractive does. Your voice is magnetic. It draws me in and makes me want more.
Some other adjectives, and not all are positive, are: angelic, refined, raspy, squeaky, old-fashioned, cute, mesmerizing, perfect, unrefined, ferocious, powerful, cold, and warm, just to name a few. Hope this helps!