Share 'A lot of Acid'

Hi! I really need advice. I keep on having problems of making chocolate that taste acidic. I've made 7 batches so far. Each with different temperature, mostly either short high or long low. Especially the long low roast a little more than half way I get this scent of acidness and at the end resulted in a little bit of a burned brownie smell. Many roast I would get this nice smell of chocolate…