IR’s - Can I use the Helix IR’s in the Kemper Profiler

    Quote from Simon S

    Or you profile your helix, but I don't know how good the result would be

    I've done this and the results are pretty good.

    Also, I can now combine the Helix Profile with the Kemper Effects. Sounds incredible.

    Kemper Stage - Macbook Air 2017 - macOS Catalina 10.15.7 - Logic Pro X

    Like 2

    To get an IR out of a hardware unit you have a several options:


    HERE ARE SOME FREE OPTIONS I HAVE USED

    1) Profile the unit using a clean tone. No amps, effects etc to just get the frequency response of the IR. However, the Kemper may see this as having no IR/CAB so you may get nothing but a clean amplifier profile with no CAB.


    2) Send an impulse into the unit and capture the output. An impulse is a single sample at some high volume. All other samples are zero. The output of the device will be a waveform of the IR. You can then drag this into the Kemper using Rig Manager.


    3) Do a frequency sweep of the device. I have used ROOM EQ WIZARD with good results. It is a little complicated getting the IR out of REW. You will need a waveform editor and some instructions. But it lets you really see what the IR is doing to your sound. Very cool.


    When I do this stuff, I am on a Windows PC. I always use Goldwave audio editor.


    For method 2, I create an impulse file in Goldwave and save it. I then play the wave file in a loop in Windows Media Player and record the output of the hardware using Goldwave. Find the best looking IR pulse, clip it, and save it.


    I think the Kemper normally uses 44.1 kHz files that are at least 2048 samples long. You can try saving in 16 or 24 bit depth.


    TIP: You can edit the IR wave files to further tweak the EQ if you want to.

    An IR is just a sound file like any music you may have. The WAVE file format is used because there is no compression. No compression/decompression means the file is perfect and not messed up just by saving. IRs are almost always MONO.


    Any Audio Editing software will have EQ options. I always use Goldwave (my personal favorite). But there are many many options.


    WHAT IS AN IMPULSE RESPONSE

    When you play an impulse(Left) thru a speaker, the impulse is turned into a softer spike followed by a lot of oscillations (right). The oscillations are the effect of the speaker trying to move, its vibrations, and vibrations of the cabinet itself.


    The image on the right is what your IR waveform will look like in an audio editing program. Notice the sharp spike and small vibrations after. Also notice there is only a small amount of time before the impulse starts. This delay creates a delay or lag in the playback of your IR. You do not want a lot of time here. Smaller is better. This delay may get removed when the Kemper converts the IR to a CAB, but smaller is still better.


    1) Make a copy of the IR/WAVE file.

    2) Open the copy IR/WAVE file in an audio editor.

    3) Apply an EQ to it just like you would music.

    4) Save the edited IR/WAVE file.


    After the EQ, make sure the IR still has a spike to it. Some filters destroy the phase response of the frequencies. You will get best results if you do not destroy the phase response. Try a different filter EQ in that software.


    The IR usually has a spike followed by small ripples. This spike sort of determines how loud the IR is. If you edit an IR and it gets all smeared, the spike disappears and the resulting IR may be much louder than the original. Especially if you NORMALIZE or MAXIMIZE the volume after editing.


    Goldwave note: Spectrum Filters works good in GW. Graphic EQ will destroy the phase and mess up the waveform.


    TRICKS

    1) In your audio editor, change the pitch of the IR. This lets you make the speaker sound larger or smaller. Larger (lower pitch) usually works best. You will get a thicker heavier cabinet sound.

    2) Apply compression to the IR to alter the frequency response and alter volume.


    Goldwave note: The default Pitch Change effect works great. Do not select Preserve Tempo, which uses FFT and can mess up the IR. Or experiment and use the FFT method, but you will need to edit the results because the spike can get moved.


    DEEP DIVE

    The IR is a plot of the sound echoes of the original impulse. If the IR was made very long in time, it could be used as a reverb. In fact, a guitar IR is basically is a very fast reverb simulation. The longest IR files the Kemper uses are 2048 samples. At 44.1 kHz that is a very short amount of time. Approx 47 mS. Not enough time to make a cool reverb. But you could make a fast slapback echo


    Since the IR is a plot of the echoes, the IR is reproduced in software by simply multiplying each guitar sample by the IR. In essence playing back all 2048 echoes at once. Since the echoes are out of time from the original pulse, they phase cancel and create a time based EQ. That is why you do not want to apply an audio editor EQ that smears the phase response. It may alter the final IR sound a lot.


    CAVEAT EMPTOR

    My brain is small. I know just enough to be dangerous. Read what smart people have said about IRs, because some of what I posted is probably wrong.