What is an Impulse Response in RM?

  • I got some helpful tips on Facebook on how to create an uniform performance by importing the same CAB across all profiles of my board. He used the term IR, and I didn't really understand him, but then he said it's a CAB.. So I've been experimenting with different CABs with great success.. However I could not shake off the feeling that IR meant something more than just a capture of a spesific CAB. Looking at Tone Junkie video of IR, I get the impression that it is a simulation of microphone placement? Does this mean that I can take a VOX AC30 that has been profiled with spesific mics, and then just swap the mics with something else? I was under the impression that once a profile has been captured, it cannot be changed.. Mic placements was already there during the profile process. The whole thing about changing CABs is really a mystery to me. How is it even possible :/

  • This is my understanding but someone might need to correct me...


    In principle, the profiling process covers the whole signal chain...amp, cab and mike.


    However, it is possible to remove the cab and change it BUT this is not an exact science as essentially it just removes the cab using algorithm to take it out...in other words it does its best to remove it.

    Unless you do a direct profile of the amp, ( which does not include the cab in the profiling) then this will always be an approximation.


    IR's are commonly using in modelling and are how the mic and cab work together. There is a whole industry for IR creation to give a more realistic sound. In the KPA you can also import IR's which are the Cabs and mics part of the chain ( I think!!).


    Someone else may want to jump in with a more technical statement!


    My personal view is you don;t need them. Its another tonal shape you can use but if you have a good profile with a decent mike, then no need to change it. I went down the IR rabbit hole and spent so money to get more different sounds...not necessarily better, just different.


    In the end i decided it was a step too far...

  • You can convert IRs into Kemper cabs with Cab Maker, a program by Kemper you can download. That way you use any IRs as cabs inside the Kemper, not added to a direct profile thru any DAW you may be using. But you may just switch cabs from other rigs till you find one that suits you. Merged profiles in theory are better for that since the studio profiles separate cabs by approximation using an algorithm as V8guitar has told you. The point is if the altered rigs work for you, that's It.

    Never too old for rock'n'roll

  • Inside the PROFILER and Rig Manager there are only cabinet PROFILEs. These can be the outsome of a PROFILING exercise or migrated from impulse responses, which are commonly used. In order to transform an impulse reponse into a cabinet PROFILE, you don't need Cab Maker anymore. You can just import or drag&drop an impulse response into the preset area of Rig Manager. In Rig Manager the impulse response will appear as a cabinet preset which includes the cabinet PROFILE.

  • Don’t worry about missing out on anything, Kemper Cabs are basically IRs on steroids. ?


    An IR is similar in concept to profiling a speaker and mic only without the amp portion. However, the way a speaker reacts WITH an amp is a two way street due to the impedance curve of the speaker interacting with the amp’s output transformer. A Kemper Studio profile captures all of this whereas an IR only captures the Speaker and Mic without the amp interaction.

    What sometimes makes people feel IR are better or more flexible is that some of the IR loaders which are available for use in a DAW or as standalone applications can simulate the effect of not only changing mics and speakers but also moving the mic position. I am not an expert on how this is actually achieved but it appears to be a combination of swapping IRs, and modelling the blend of different IRs to create the impression of actually moving the mic etc.


    Cabs are at least as good as IRs (arguably better) but the choice of what works for any one person is just personal taste rather than quality.

  • One interesting experiment is to profile an amp/setup that uses an IR as part of its cab section (maybe another modelling system or real amp with some kind of speaker load-box/sim using IRs) and then swap the kemper-cabinet for the actual IR used. This will reveal a bit of how the profiling process guesses the sound of the cab.

    Likewise, you’d think that creating a cab IR from a kemper profile (by isolating just the cab section) should yield similar results but, again, this can lead to some interesting findings.


    Apologies if i’m heading down another path...