Introduction

Virtual Grand Master, or VirtualGM for short, is a software simulation of a Grand Master lighting control system, installed in UK theatres from the 1920s until the 1950s. To find out more about the original Grand Master, see the About screen (select About in the Help menu on a Windows computer, or in the Application menu on a Mac).

VirtualGM is designed to show how a Grand Master worked, and how it was used to operate the lighting for a show. Grand Masters and similar lighting controls of the period worked in a very different way to modern controls, or indeed to the manual ‘preset’ controls that came after the Grand Master type, and before computerised memory control systems.

Before starting to use VirtualGM, please read about how the original Grand Master worked, in the About screen.

Using the Interface

Controlling a single dimmer
Click and drag the handle of each dimmer to set the level between off and full, or use your mouse scroll wheel while hovering your mouse over the dimmer. If you open the Stage tab (select Stage in the View menu), you will see the output intensities of the dimmers.
The Full On and Off buttons override the dimmer setting of the handle; use the middle Dimmer button to give control back to the dimmer handle.

Controlling a group of dimmers on a shaft
Select the check-box under the dimmer handle to lock the dimmer to the shaft. Then turn the wheel of the shaft: click and drag the handle in a circle, or use your mouse scroll wheel. Any dimmer locked to the shaft will move with it - up as the shaft handle is turned clockwise, and down when turned anti-clockwise.

In the centre of the window, each shaft has a blackout switch, which overrides the settings of all dimmers on that shaft. Release the blackout switch to restore the dimmers to their individual settings.

Using the Grand Master
The grand master wheel controls any shaft that is locked to it. Use the shaft clutch settings Up or Down to lock that shaft to the grand master wheel. If Up is selected, the shaft will turn clockwise when the grand master does; if Down is selected, the shaft will turn anti-clockwise. Select Free to uncouple the shaft from the grand master.

In the centre of the window, there is a master blackout switch, which overrides the settings of all dimmers and blacks out the entire stage. Release the blackout switch to restore the dimmers to their individual settings.

Using the keyboard to control the shaft and grand master wheels
As well as using the mouse, the shaft and grand master wheels can be controlled from the keyboard. This is useful when operating a show, as it allows the mouse to be used to control individual dimmers, shaft clutches, and so on, while also turning wheels.

The grand master wheel is operated by the left and right arrow keys. The shaft wheels are controlled by the following keys:

 - Red shaft: Q and A
 - Green shaft: W and S
 - Blue shaft: E and D
 - White shaft: R and F
 - Auxiliary 1 shaft: T and G
 - Auxiliary 2 shaft: Y and H

You can press the key once to get a small movement of the wheel, or press and hold to get continuous movement. Holding down the shift key while operating a wheel with the keys will give finer control, moving the wheel more slowly.

Note: the effect of pressing and holding keys will depend on the keyboard repeat settings of your computer.

Operating a Show

Operating a Grand Master is quite different to other types of lighting control. The only thing you can prepare in advance of a cue is to lock the dimmers you want to move to the shafts, and the shafts to the Grand Master. This means that you need to think through in advance which dimmers need to move, and in what direction.

To bring up a lighting state from blackout, lock the dimmers you want to their shafts, and lock those shafts to the Grand Master wheel. On cue, turn the wheel to bring the dimmers up. Note that all dimmers will come to the same level.

To create a cross-fade, select some shafts to increase on level, and others to decrease, when you turn the Grand Master wheel.

Small changes can be done by adjusting individual dimmer levels.

Use the blackout and full-on switches to do 'snap' cues – you can blackout shafts or the whole stage, set the dimmer levels, and have them come on instantly when you release the blackout switch.

Remember that the dimmers on a single shaft cannot move in different directions, unless you operate them individually. (This was done on real Grand Masters, which often required two hands and even feet to operate, or several operators for busy shows. Replicate this by using the keyboard controls for the shaft and grand master wheels while operating individual dimmers with your mouse).

Using Art-Net

VirtualGM can output DMX data from your computer's ethernet port using the Art-Net protocol. You can use this control a real-world lighting rig, or a virtual rig in a lighting visualiser. To use the Art-Net output from VirtualGM:

1. Disconnect your computer's ethernet port from any network it may currently be connected to.

2. On your computer, go into the network settings and set the IP address somewhere in the range '2.0.0.xxx', such as '2.0.0.1'. Set the subnet mask to '255.0.0.0'. You may have to select 'Set the IP address manually' to allow you to make these settings. These settings vary between operating systems, so if you need additional help, search online for 'set IP address manually' and your operating system and version (such as 'Windows 12' or 'Mac Monterey').

3. Connect your Art-Net device or network to your computer by ethernet.

4. Select 'Connect' in VirtualGM's 'View' menu.

5. Click the 'Connect' button in the Art-Net section. The DMX outputs that are available in your Art-Net network will be listed. Select the one you want to use by clicking on it.

By default, VirtualGM outputs to DMX channels 1 to 24, but you can change the DMX address of the first channel if you need to, using the pop-up menu.

Note: it is very important you set up your computer's network correctly before using Art-Net output, to avoid polluting your network or the internet with broadcast UDP data.

Art-Net is designed by and copyright to Artistic Licence.

Using LanBox

VirtualGM can work with a LanBox LCX DMX controller to control a real-world lighting system. VirtualGM will communicate with the LanBox via an Ethernet connection, using the UDP protocol:

1. Select 'Connect' in VirtualGM's 'View' menu.

2. Set the port number and IP address of your LanBox. By default, the port and IP address in VirtualGM are set to the LanBox's default values, so you only need to change these in VirtualGM if you have changed them in your LanBox.

3. Set your computer's networking settings according to the LanBox manual's instructions for using UDP.

4. Connect your computer and the LanBox with an ethernet cable.

5. Click the LanBox 'Connect' button at the bottom of the VirtualGM window.

Note: it is very important you set up your computer's network correctly before using LanBox output, to avoid polluting your network or the internet with broadcast UDP data.