do I still need a air regulator if I have a double action air brush

Tools, Techniques, and Reference Materials Painting and airbrushing
1

just trying to save a few bucks if I can

2

yes, you will still need a pressure regulator my friend. the double action has nothing to do with controling the psi. later.

3

Yes, if you want to be able to control the air pressure.
A double action-airbrush is not designed to control the amount of air, it is designed to control the amount of paint only. It is called a double-action because the air on or off and paint flow are both controlled by the trigger.

Mike