This is the most important part of the setup as it takes the information from the players (playing the keyboards), processes it into sound and sends the sound out to the amplification system. Laptops are more convenient but you could use a desktop computer if you like. Both PC and Mac systems are supported by RMS however we only supply Windows laptops. It's not essential but we recommend at least a 1600x900 resolution screen if using two or three keyboards from one machine if you like having all the windows open. You could always run a duplicated slave monitor off the laptop to make it easier for everyone to see the screen. Matt screens are also better to cut down reflections, especially useful if the band is on stage.
There are two crucial things to look out for and unfortunately you will likely have to 'suck it and see' if your own computers will work (use the demo RMS software). To avoid crackling and noisy sound and/or dropouts in sound the computer must have a good DPC latency and very good USB (or Firewire) hardware if using external audio interfaces. DPC latency can be checked by either/both of these:
These are both for the PC, Mac hardware is usually fine as it’s based on Linux which is designed with this sort of thing in mind. Anything which shows in red (large spikes or warning text) might result in random noise, bangs etc.
If using an external audio interface, your USB/Firewire hardware must be fairly recent and efficient. Firewire chips should ideally be Texas Instruments ones and USB hardware based on ICH8, 9, 10 or later (e.g. Sandy Bridge). Some useful information is here - http://www.rme-audio.de/en_products_fireface_uc_systems.php?page=content/products/en_uc_general
At Liquid Productions we have a high-spec, expensive three year old gaming laptop which is more than capable of running everything... but has terrible USB issues and gives constant crackles. On the other hand we also have a fairly cheap off-the-shelf low power laptop which has no USB issues at all. Typical!
The laptops we hire out for RMS use are custom designed to a very high specification using i5/Sandy Bridge hardware. They have very nice 15.6" 1920x1080 matt screens so you can see everything clearly and are tuned to running streaming audio. You can run up to three keyboards from the one machine, line of sight and space permitting.
Assuming you're running a show which uses three keyboards (Les Mis, Aida etc.), you can plug them all into the one laptop as shown here. These are the USB 2 ports and have the mouse and Babyface plugged in.
On the other side we have a USB 3 port - this has the Fireface plugged in. It's best to do it this way round as the USB 2 and 3 controllers are separate which helps to minimise any timing issues or conflicts (potentially resulting in random noise and pops) as best as possible.
The picture below shows the connections at the other end. The Babyface has a single USB cable going to the laptop for data and power plus a 'breakout cable' which contains the MIDI, audio and headphone sockets. The Fireface has a separate power supply with a breakout cable for the MIDI but this time dedicated audio connections. See the 'Audio Interfaces' page on the left for more information.
Shows with fewer keyboards work just the same way but with fewer connections.