As Steve said, depress it towards the 'Open' side.
You can always check it by setting all four switches to the 'Closed' side, and then all four towards the 'Open' side.
You'll notice the difference right away in the 24 dB change.
Chuck
You can always check it by setting all four switches to the 'Closed' side, and then all four towards the 'Open' side.
You'll notice the difference right away in the 24 dB change.
Chuck