Hello Mike,
The left pedal increases the volume, but only very slightly, and not enough to be usefull..
The left pedal is a swell pedal, not an overall volume pedal - it controls the shutters on the virtual swell box model, and (only) affects the ranks on the Swell division (keyboard), which are enclosed in that swell box (as on the real St. Anne's organ).
A swell box does affect volume (amplitude) to some degree (its effects vary from rank to rank), but it also affects harmonic content. (Real pipe organs don't have a volume pedal!)
Have a look also at the following sections in the Hauptwerk user guide (on the Help menu in Hauptwerk):
- 'Background A brief tour of a pipe organ' (starts on page 67 in the v3.30 version of the guide).
- 'Using Hauptwerk: The virtual console' (starts on page 72).
You can adjust Hauptwerk's overall output level on the 'Organ settings | General options' screen, and in your audio interface's control panel. For best audio fidelity you should aim to set the levels all as high as possible without clipping (audio distortion) occurring on full organ.
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.