Is it possible to control water pressure using a ball valve?
To answer your question;  A ball valve only controls flow not pressure. A few seconds after water is flowing a ball valve will limit the pressure based on the flow. A pressure regulator requires no more plumbing than a ball valve. A regulator will limit the maximum pressure but not flow until the set point is reached. If you can answer the question. 
Why do you want to limit pressure or flow. We may be able to point you in the direction you need.