What is an IR?

[stevecloud75]

Just asking.  I hear about them a lot, but can someone explain what they are, and how they’re used with the Helix?

[silverhead]

Without getting into details, an impulse response (IR) is a tiny piece of DSP (digital signal processing) that is applied to a digital audio signal to simulate the effect of having that signal routed through a real-world guitar cabinet and microphone combination. In the Heilx world it is used to replace the cab/mic model in a preset.

[datacommando]

On 5/30/2024 at 8:18 AM, stevecloud75 said:

Just asking.  I hear about them a lot, but can someone explain what they are, and how they’re used with the Helix?

Hi, 

 

In much the same way as light can be used to capture a photographic image, likewise audio can create a sonic snapshot of the acoustic characteristics of a speaker cabinet and microphone placement in a specific room, ambient space, etc.

 

Loading an IR which contains that sonic snippet into your Helix, should allow you to playback through it, to recreate the particular sound that was captured. Commercial IR packages can contain hundreds of these audio snaps captured by various mics at various positions within a given space - you simply need to audition each one until you find the one of your dreams - it could take quite some time. Alternatively, you could use the new cabinet modelling built in to the Helix , which is essentially thousands of IRs and a lot easier to navigate.

 

Also, see page 37.

 

https://line6.com/data/6/0a00050b287e6643b71cda93a/application/pdf/Helix 3.0 Owner's Manual - English .pdf

 

Hope this helps/makes sense.

 

[theElevators]

There are also acoustic guitar IRs, reverb IRs as well.  But yes, most commonly an IR is a replacement for the mic'ed cab sound. 

[cruisinon2]

All of the above plus the following:

 

IR = Immense Rabbit hole...;)

 

While they can be useful, you'll find that the commercially available IR packages typically contain dozens, if not hundreds of individual IR's that you then have to audition one by one until you find the couple/few that you'll actually like. It's easy to lose hours on end trying to discern what are often very subtle differences. The current onboard mics and cabs are much improved over earlier firmware versions... imho it's easier to get a handle on adjusting those to your needs. IR's are a fixed result that can't be tweaked... you either like it, or you don't.