I've been using the SM58 for a decade. I recently bought the Beta 58A. I do see a positive difference. It simply sounds better. It's bit more sensitive. Frequency response is better. I've not used any special gadgets to technically see the difference. But just recording and listening to the vocals convinces you that this is great. Build quality is awesome!! I guess the SM58 and this one (Beta 58A) will last forever. No expiration date on these even if you happen to use them daily!!