[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/Tulxy.jpg

Use this node setup, setting up AO in principled is the same as any other node.

The **AO** in this node setup basically does two things:-

> 1. Determines the colour of the AO. As you can see the color of the **AO** is plugged into the **Mix RGB** node. I additionally added a color ramp to intensify the **AO** effect.

> 2. Determines the distribution. In this node setup the **Alpha** of the **AO** is used to determine the distribution, as the AO is being **Overlayed** on the diffuse texture. Similarly, you can use the **AO** texture to control the distribution of other additional shaders or just use it directly.

Blendfile:- [<img src="https://blend-exchange.giantcowfilms.com/embedImage.png?bid=4549" />](https://blend-exchange.giantcowfilms.com/b/4549/)