Dood

@Muppet  Thanks.  So:

'Simply put, an impulse response (IR) is an audio file that contains a capture of the inherent sonic characteristics of a piece of gear, acoustic environment, or playback system. IRs were first used to recreate unique acoustic spaces in reverb processors, and they changed the professional music mixing game by making huge rooms like the Sydney Opera House available as studio reverbs for the first time.'

If you like coloured speakers Dan, I could come to your studio with a big box of crayons and get scribbling.  It might not be what you had in mind but I'd gladly do it for free to get some current knowledge.

Heeheehee.  Enjoy.

Thank you for the responses! Yup, that's pretty much it. A digital representation of the combination of a number of devices or spaces. It could be, the sound of a speaker and microphone combination. It could be the natural reverb of a cavern space being mic'd up. It could be as simple as an EQ curve that you could apply instead of using a whole graphic equaliser - which is great as an IR takes up less processing power than a full spec EQ plug in in a DAW.

The 600 I mention in reality isn't actually 600. It is however about 15 or so different cabinet and microphone combinations (Shure, Neumann, AKG, Royer etc) all 'profiled' in different positions (which affects tone) then 'saved' in a number of different useable formats.