Sorry about that! IR stands for Impulse Response. It's essentially a form of plugin to add to your signal chain so you can sound like you're going through a mic'd speaker cabinet. Example: add an IR of an Ampeg B15, and it mimics the sound of you playing through a mic'd B15 without actually having a mic'd B15.
Most impulse responses are models of amps & cabs and are typically used in studio recording or in-ear monitor situations where you aren't using an amp. Depending on the IR you choose, you could instantly go from the sound of a B15 to the sound of an Ampeg SVT/8x10 just by loading a different model. But in this case, 3Sigma has created models of acoustic upright basses. So by adding the Hawk IR into my Stomp, my NXT sounds more like a mic'd acoustic upright instead of a dry NXT.
To use an impulse response live, you'll need a piece of gear that lets you load an IR into it. In my case, I'm using a Line 6 HX Effects or HX Stomp, which let you load impulses and add them into the signal chain as an "effect." You can even assign them to a footswitch and turn them on/off.
Because of the sound sculpting nature of impulses, the big trend right now is to use them with FRFR (Full Range Full Response) cabinets... speakers that don't color the sound... and then use a chosen impulse to change the character of the sound to whatever the impulse is modeled after.
Hope that helps at least a little!
5sg.
I'm definitely anxious to get this IR into a live situation(s) and do some more dialing in (my instinct says I'll probably dial the tone knob back). It will be interesting to see if my fellow bandmates have any feedback.
