Master volume
From Box Of Stops Online Help
The master volume is the slider across the top of the screen in Box Of Stops.
This controls the volume of all the stops on the organ. In fact it sets the maximum volume any stop can play at, and combines with the individual volume for the Bank and the Stop. Please see the page on Combining volumes for some more precise detail on how this works.
To find more about how to control the master volume, for example with a volume pedal, please see the section on volume pedals on the main Registration page.
