Posts by Robrecht

    The specific nature of Air Chorus is that the modulated signals don't mix in the same channel, but "in the air between the speakers". The effect is much more subtle than the hard beating you would get from combining mutually detuned signals in the same speaker.

    For that reason, as soon as you would mix in some dry signal, the effect would suddenly become much more pronounced instead of being regulated like you expect.

    I believe that is the logic behind the omission of a mix parameter.

    That Harley Benton cab is advertised as full range (i.e., not a traditional guitar cab that colors the sound) so it should in theory sound at least similar to what you get in your headphones. Some thoughts:

    • I see that the cab has "Resonance" and "Presence" dials, implying that some coloring is still going on. That may explain some of the difference.
    • How are you connecting the cab? The most standard way would be to use the Monitor output from the Kemper, making sure that the "Monitor Cab Off" option in the Output settings is not engaged. Since your cab is not a traditional guitar cab, the Kemper needs to provide that part of your sound as well, just like it does to your earphones and the PA. (Just checking, you've probably figured this out already.)
    • Raising your cab, as has been suggested, can make a huge difference. A full range cab on the floor can sound very boomy, plus you're currently sending most of your sound energy to below your knees.
    • Finally, it's true that even a "full range" cab will never sound exactly the same as a pair of headphones. "Full range" is never entirely "neutral" (and that goes for the headphones as well). Also, even though the Kemper isn't like a traditional amp where the valves behave differently at high power, our ears do respond differently to the same sound at different volumes. For that reason, you should ideally audition and select your profiles at the volume you'll be playing at, or at least expect to have to tweak profiles that sounded good at home.

    If you get a chance, it could be useful to try out your Kemper at high volume on a different full range system, like a PA or an active monitor speaker. If the result is closer to the sound you're after, you'll know that it's not just a matter of volume, and that you should try adjusting the positioning and/or settings of your Harley Benton cab.

    I have a question that is probably not specific to the Kemper, but I can't seem to find an answer elsewhere.

    I use NRPN messages to control the Looper in a couple of songs. The correct way to send them, according to the Kemper MIDI Parameter Documentation and common MIDI practice, is as follows:

    CC99 (MSB/address page) 125 (for Looper)

    CC98 (LSB/address number) 88-94 (varies with intended function)

    CC06 (MSB of value) 0

    CC38 (LSB of value) 1 (to simulate button press) or 0 (to simulate button release)

    I have entered these four messages in the correct order (at the same timestamp), but I have noticed that my MIDI editor displays CC98 before CC99:

    Since they are on the same timestamp, both messages are "simultaneous", but presumably CC98 is sent before CC99 in the MIDI stream, as displayed. Is this a problem?

    Note that the MIDI file does work: I've used it like this in countless rehearsals and shows, and the Looper does exactly what it should. But I wonder if this simply "luck", perhaps due to the fact that I'm only ever addressing page 125, so this stays the same for subsequent messages.

    So, my question is: does the order of MSB/LSB matter if they are on the same MIDI timestamp?

    I'm not in front of my Kemper right now so this is from memory, but here are two things I can think of.

    * The Voice Balance parameter plays a role in the way the Stereo knob works. If you enable only one pitched voice (by turning Voice Balance all the way to the left or right), the Stereo knob pans the unpitched signal to one side and the pitched signal to the other side. If you enable both pitched voices (by leaving Voice Balance somewhere in the middle), the Stereo knob pans those pitched voices left and right and leaves the unpitched signal in the middle. So, in your case, make sure that Voice Balance is all the way to the left or right.

    * I'm not sure if this applies to the Chromatic Pitch effect, but I seem to remember setting the Stereo parameter beyond 100% enables something Kemper calls "super-stereo", which makes the stereo image appear wider than the physical distance between your speakers if you stand in the correct position between and in front of them. Now this is speculation, but I imagine "super-stereo” works by mixing a bit of the right channel into the left channel, and vice versa, but phase-inverted, to cancel out all hard-panned signals in the middle. If you listen to each channel separately, or in headphones, the cancellation in the air between the speakers does not happen, which might give you the impression of the opposite side bleeding through. So, tldr: try 100% stereo instead of 200% to avoid this.

    Edit: Sorry, I just gave it a spin and my second point doesn't seem to be correct, at least for the Pitch Shifter effects. There, as far as I could tell, 200% simply means a hard pan, without the "super-stereo" mid cancellation (which seems to be specific to the Delay effects).

    It's hard to tell while playing because the direct sound of the strings always bleeds through, but I think with these settings of Chromatic or Harmonic Pitch I was getting full L-R separation between pitched and unpitched signal:

    Voice Balance -50% (i.e., using only the first pitched voice)

    Mix 0% (same volume for pitched and unpitched signal)

    Stereo 200%

    First thing to check, since you're using the Monitor out: the "Monitor Cab Off" option in the Output settings. It should be unselected, like in the picture:

    just a question, how do you guys cope with the latency, I remarked it takes a while to jump from performance to performance, and it's a little faster from slot to slot... is it something i can anticipate and it'll stay consistent?

    Sorry, I didn't see your question before. I'm not sure if the latency is consistent and predictable... I just keep changes in a song within the same performance, they're fast enough from slot to slot for me not to notice them. I basically have a separate performance for each song, so the switch between performances happens between songs.

    The Main Manual is essential reading as you get to know your Kemper better, but you did nothing wrong going by the Quick Start Guide initially, which should tell you all you need to know when you just want to start playing for the first time! Since you ordered a powered Kemper, it was only natural to assume that's what you'd received, and to link what you read about the Monitor/Speaker Output to the one output you saw on the unit...

    Anyway, I hope the store makes it right as soon as possible.

    Hey Burkhard , you're describing what I called the "footpedal button press" approach in my post above, essentially imitating a short on/off click of a momentary footswitch. You're right, it works fine and is a good option for many people!

    The reason for not resetting a CC to 0 until you switch to another slot is that it allows you to start playback anywhere in the song. MIDI chasing will trace that CC back, find out that it was set to 1-127 at the beginning of the section, and re-send that value to the Kemper, so that the Kemper switches to the appropriate Performance slot, even if you haven't passed the start of the section where the switch is programmed.

    So as long as you make sure no two of CCs 50-54 are set to 1-127 simultaneously, MIDI chasing can be quite useful!

    Of course, even with that method, it isn't necessary to send all five of those CCs for every slot switch: it's enough to only set the previous one to 0 and the new one to 1-127. Sending all five every time (four of them 0, one 1-127) is just a redundancy thing I do: when you're writing a song and moving things around, it's harder to keep track of what CC has been "activated" in the previous section and should be turned off next. Turning all of them off every time (except for the one you're turning on) helps to make sure there are no stray CCs accidentally left on.

    But again, you're right, in many cases a quick "button hit and release" is a better, and certainly more straightforward option!

    BUT HERE IS THE TRICK, which fixes the problem: Every time when I send a ControlChange that lets the Kemper switch to a slot I also send the ControlChanges for the other slots with value 0 - just a short time before.

    I do the exact same thing. I don't think it needs to happen before the actual switch -- I usually just send all five CC's (50-54) simultaneously, all zero except the one I want to switch to. But yes, definitely the right solution!

    (For anyone wondering: alternatively, you could always stick with the basic "footpedal button press" idea and just send the same CC twice in short succession, once with a non-zero value (to activate the slot) and then with value zero (to "take your foot off the pedal"). A short "click", as it were. But then you wouldn't get the benefit of MIDI chasing if you start the song in the middle of a section, since all of the CC's would then be zero most of the time. For that reason, it's best to keep the CC for the desired slot at non-zero for the whole duration of the section where that slot needs to be active (as if constantly keeping your foot on a button) -- as long as you remember to "clean up after yourself", i.e., make sure all of the CC's for the slots you don't want active are reset to zero.)

    "Boot from USB" is just a term.

    I suspect HankLinderman 's original idea was somewhat inspired by the concept of a "portable operating system", where you can have, say, an entire Linux distro on a USB stick, including all of your user settings and files. If you plug it into any computer, even if it's a Windows machine, you'll boot into your own personal environment, which has nothing to do with what is installed or stored on the computer. During the entire session, the operating system, installed apps, settings and user files are all read from and written to the USB stick directly, bypassing the computer's own storage: nothing is installed or overwritten on its hard drive. Unplug the USB and the computer will boot up normally again, totally unaffected.

    As a concept, I thought that was pretty cool, although I suppose it's probably not possible on the Kemper for technical reasons.

    Thank you for the optimization tips though, a special lightweight "concert image" is an excellent idea!

    I don't know how technically feasible it would be, but at least in theory this is a very good idea. Sure, you can take out your laptop on stage and copy some performances over, or wait ten minutes while you flash an entire backup from USB, but those are not fun things to do during a fifteen minute changeover between bands. And then there's the uncertainty of what version of KAOS the local Kemper will be running...

    If the boot image could include everything – profiles, performances, system settings and even the operating system – setting up would be as simple as just plugging one more thing in besides your guitar before turning the Kemper on.

    There's two kinds of latency at play here, no?

    The first one, let's call it "control latency", is the lag between the player's manipulation of the physical whammy bar and whatever the floor unit needs to do in response. I imagine this should be very close to zero, as it only requires a relatively "lean" control signal to be transferred and processed. Wiggle the bar and the floor unit should react virtually instantaneously, even if the connection were wireless, as there's no audio stream passing between the whammy bar and the floor unit.

    The second kind of latency, let's call it "audio pitch shifting latency", happens entirely within the floor unit and is inherent to any pitch shifting algorithm. You would theoretically notice it when picking notes while holding the whammy bar down, for example (like chu says, not something you would traditionally do a lot), or using the "virtual capo" feature.

    It's entirely possible this device has less pitch shifting latency than the Kemper, although I personally think the Kemper's is not bad at all. However, "zero lag" seems like marketing hyperbole when it comes to this kind of latency: real-time pitch shifting simply takes a non-zero amount of processing time. Like Monkey_Man said, the best you can hope for is "not-perceptible" (which is good enough, of course!).

    That said, I would be interested in this without the on-board audio processing in the floor unit, just as a (preferably wireless) control device. Make the floor unit simply output a MIDI cc or expression pedal voltage signal and leave the processing to the Kemper!

    The only challenge would then be that the Kemper expects a traditional expression pedal, which is unipolar, i.e.: it goes from zero in the heel position to 100 in the toe position. To use this as a whammy bar, which goes both up and down, you'd have to be able to define a middle position in the Kemper where the guitar signal is unaffected, which could take a bit of tweaking to make it correspond to the whammy bar's physical middle position. But it would be cool to use it for morphing!

    Edit: I guess the latter issue could be solved if the floor unit acted like two separate expression pedals, one for pressing the bar down and one for pulling it up. Connect it to the Kemper using two TRS cables and you can control two different effects, depending on the direction!

    I don't think that's possible. :/

    You can unlink the headphone out's volume so that it no longer responds to the master volume knob, allowing you to change the main out volume while leaving the headphones out as it is. But that setting doesn't affect the muting behavior of the tuner, and manually turning down the volume every time (and then quickly turning it back exactly to the original volume!) is a lot less convenient.

    Could be a feature request!

    For reference, here's the exact same clip from my first post, but with a notch EQ at 8.7 kHz (and at 17.4, although that one probably doesn't make much of a difference to most of us). If you go back and forth between both, the ringing is very obvious in the first one.

    pasted-from-clipboard.png  pasted-from-clipboard.png

    With this EQ, it sounds great and perfectly usable to me. Like I mentioned, I can use the Kemper's Studio Equalizer to do more or less the same thing, but then I'm using up an additional slot just to correct the Acoustic Sim.

    To be honest, apart from this ringing, I'm not having any issues with the Acoustic Sim (forgot to mention I'm using it with the amp section turned off). It's hyper sensitive, though, with a lot of high-frequency content that makes it sound alive, so I can imagine any single coil hum or electrical noise would be greatly amplified. I'm lucky to have a pretty electromagnetically quiet room, I guess: my Strat generally behaves very nicely.

    I've started to notice a high-pitched tone while using the Acoustic Simulator with a compressor in front. I've tried it with different guitars and different cables. It's especially noticeable with active humbuckers (Seymour Duncan Blackouts in two different guitars) at settings I would otherwise love to use for recording. I can clearly hear it with my Strat as well, but only when I turn up the compressor and the Sparkle parameter in the Acoustic Sim higher than I would normally do.

    Here's an audio example. It's already noticeable during the broken chords at the beginning, but it gets louder as I play more softly. When I mute a note, however, the ringing is also muted. Is this a tone that is already present in the output of my guitars, gets boosted by the compressor and somehow excites the Acoustic Simulator? Or some kind of artifact from the Bronze and Sparkle parameters?

    Compressor in slot A

    Acoustic Simulator in slot X

    Pickup 2.0

    Body <0.0>

    Bronze +2.5

    Sparkle +2.4

    I'm seeing two peaks, around 8.65 and 17.3 kHz. When I use the Studio Equalizer to attenuate precisely those two frequencies (max Q, gain at -18dB), the ringing virtually disappears. Anyone else getting this?

    Edit: On reflection, I suppose "hiss" isn't the right word, as it suggests diffuse, high-frequency white noise. Some of that is present, too, but it isn't as intrusive. The sound I'm referring to here is a focused, sustained, pitched tone.

    Sure, not disputing your choice, I'm just trying to figure out the reasoning behind the absence of a mix parameter.

    A mix parameter is commonly used to make an effect more subtle by combining it with the dry signal, so I assumed that is what you were after. But in this case, turning down the mix from 100% wet to 50% wet, the effect would become less subtle. I think that would confuse a lot of users, even though the result might be interesting.

    The manual says a mix parameter "would contradict the character of the effect". :/ I think this is because the Air Chorus achieves its subtle effect by modulating the pitch of both sides of the stereo signal independently, so that they are mutually detuned but only mix in the room, or "in the air between the speakers", as the manual puts it.

    The moment you would mix this effect with the dry signal, that subtlety would be lost. The detuned signal and the dry signal would be pushed through the same speaker, making the detuning effect much more pronounced, with audible "beating".

    In that video, it seems like Feedback is set to Max, so the delay buffer keeps repeating without decaying. Hence the suggestion by CelticGibson to activate "Infinity", which ups the feedback for as long as it is engaged. But you could also just turn the Feedback parameter to 100%.

    For the pitch shifting effect, however, you have to disable "To Tempo". "To Tempo" sets the delay time in note values, i.e.: it jumps between discrete multiples or divisions of the current tempo in BPM. For pitch shifting, you need to be able to adjust the time continuously in milliseconds.

    Quote from manual

    If “To Tempo” is not engaged, then Delay Time controls the absolute delay time in milliseconds. The maximum delay time is 2000 ms. As you dial through the delay times, you will notice the change in pitch, typical of tape-speed changes in a tape delay.

    I've just given it a try using the Single Delay algorithm (others should work too, for more complicated patterns). I don't know if it sounds exactly like the example in that video, but disabling "To Tempo" does make the delay pitch-shift like a traditional tape delay as you turn the Delay Time knob.


    So the job of the pitch shift in the mentioned rig (Steve Stevens) is to double the guitar (or let it sound "fatter")?

    I don't know about this specific rig, I haven't tried the new collection yet. But the Kemper has other tools for doubling/making "fatter" (like the new Double Tracker effect), so I would assume it's meant to add a harmony line, either a parallel octave or fifth, or thirds or sixths... Kind of like the classic rock thing where two guitarists play in harmonies.

    About the placement of the effect, musicmad summarized what I meant to say quite well: placed before the amp, the result sounds more like a two-string chord (a powerchord in the case of an added fifth) coming from a single guitar. It won't sound as defined and the two voices won't be as discernable as when the effect is placed after the amp.