Troubleshooting How do I use my Philips volume diffuser? The volume diffuser has been developed to dry your hair quickly and evenly to minimise frizz and add volume. To use the diffuser, do the following. Attach the diffuser onto the dryer To add volume at the roots, make sure that the pins touch your scalp. Make rotating movements with the dryer to distribute the warm air evenly through your hair. To remove the volume diffuser, simply pull it off.