Profiling goes wrong sound

  • Hello,

    I've been using my Kemper for a long time as studio hardware, but mostly using clients profiles. I did just a couple of low gain profiles until today and everything was apparently right. Today I tried to do a high-gain profile from this chain:

    Kemper -> Peavey 6505 -> Mesa Boogie 4x12 -> 2x SM57 -> Lynx AD Coverter -> Cubase 11 (1.5ms latency) and mix the two signals -> Lynx DA Converter -> Kemper

    While I listen to the reference amp (the 6505) it sounds supercool, so I go for the profiling, and after that the result is like distorted, like if I would have cranked my pickups up, and adding a lowpass. When I'm in the last page and do some refine, it is still the same, and so different from the original. Trying the A/B here in the last page is like day and night.

    I already checked:

    - No pedal ON in the new profile.

    - Incrase/decrease input level and/or the output from my computer.

    - Add/cut some latency.


    Any thoughts here?

    Thanks in advance!

  • I ran into similar sounds when profiling my Line 6 PODs. The Kemper seemed to output a very hot signal that overloaded the input to the PODs. I put an EQ pedal in front of the PODs and decreased the volume coming in and got much better results. My first attempts were to put an EQ after the profiled device because the profiles seemed very bass heavy. That helped a little also.


    But having an EQ before the POD with some volume and Low/High cuts helped the most. I have also got some great results with a mid cut since my profiles seem to sound mid heavy (400-900 Hz).


    You may not see the overload problem with the high headroom of a Tube amp. But maybe something is clipping somewhere else in your signal chain. Or maybe the low frequency signal coming into the 6505 is the issue.


    It would be great of there were some controls on the Kemper to set max output volume etc. Since it has to play a balancing game of adjusting its output gain and its input gain to get the right feedback. And maybe a frequency limiter? Is it outputting a signal at like 20 Hz, which the device normally would never see, and it is wreaking havoc? I have not studied the Kemper output waveforms yet.


    Your problem could also be 100% latency. I do not have any experience with that. Since you are saying it sounds like a LOW PASS roll off, I would almost bet latency is the issue. If they are measuring response during the WHOOSHING sounds and you have latency, it may be sampling the amplitudes during the quiet in between whoosh moments. Which would create a low pass effect.


    In a perfect world Kemper would time align its signals. Dont know if they do. There is an IMPULSE TICK noise that could be used for this but it happens mid profile.


    Best of luck to you. I think profiling is the coolest thing ever made and think someday we will stumble onto the perfect formula to sculpt amazing tones.

  • Thanks for your answer RosboneMako!

    The point is that in the A/B stage, when I can do the refine thing, I can hear the amp signal perfectly sounding. So it seems to me that the signal gets well into the Kemper. So no input clipping. Also I increased/decreased the signal from the computer to check if I was hitting so hard to the Profiler input, but the result was the same.

    The problem won't be latency, as long as I already changed it in my computer. Same results from 1ms to 5ms.

    Let's see if there's someone who got the same problem here and can give a hand too.

    Thanks again for your kind answer!.

  • Thanks for your answer RosboneMako!

    The point is that in the A/B stage, when I can do the refine thing, I can hear the amp signal perfectly sounding. So it seems to me that the signal gets well into the Kemper. So no input clipping.

    Your guitar puts out a certain voltage. That voltage is dictated by the pickups, how hard you pick, cable, and the input impedance of your amplifier. That is the voltage your amp expects to see. When you are A/B ing, the Kemper may just pass your guitar signal thru untouched. Meaning your guitar puts out .3 Volts AC and the Kemper just switches it to the output at the same exact voltage .3 Volts AC.


    Now once you start profiling, the Kemper is making its own voltage. And that voltage may be no where near .3 Volts AC. And/or it is passing really low frequencies your guitar will not. This is where I feel the problem can exist. You can hear it slowly raise the voltage to get a sense of how the distortion curve is on the amp. My feeling is, it sometimes over shoots and applies too much voltage. Your amp expects .3 VAC and it is getting .75 VAC so it breaks up from clipping, etc. which results in a weird breakup/distorted sound.


    Another good reason to profile with less gain than you want to use on the Kemper.


    So my solution was to limit the voltage and frequencies entering the amp.


    There are too many variables at play here to know for sure. It may be as simple as the guy calibrating the output voltage was drunk the night before and missed that step on the setup. So some profilers may work better than others, etc. Having a KEMPER service manual would be a great help to know for sure.


    Hopefully all of my guesses are completely wrong and someone much smarter than me hooks you up!


    Cheers

  • I suspect the issue lies somewhere in the Lynx AD/DA conversion and/or Cubase. As there are quite a few variables at play, I would start troubleshooting by simplifying the signal path as far as possible.


    Does the amp profile correctly with just a single 57 plugged directly into the KPA? If so then we at least k ow the KPA and Amp are working correctly.


    Next can you summ tue two mic signals with a simple analog mixer? If it works we know the problem isn’t the two mics.


    Then, can you send a single mic straight through the Lynx (without going through Cubase? If that works the problem is in Cubase. If it doesn’t the problem is the converter.

  • I would definitely simplify the signal chain. I have done profiles of my amps using a microphone, small analog mixer and the Kemper (obviously a few cables as well) and they came out great. Going through your DAW could definitely be problematic. You are adding the interface and the computer in the signal chain.


    Try it with one microphone first. You may be able to gain the microphone up with just the Kemper and not need a mixer in the middle. I used one because I had it and figured I could gain the microphone up to where I wanted it then feed it to the Kemper. If you have a mixer you could go with two microphones if it works with one.

  • Simplification is the way to go in order to understand what is causing the issue.


    Other than that I'm wondering why you want to use two microphones of the same type. What is the value add? Usually people use one microphone to capture the speaker sound closely - this is a typical application for the SM57 - and another to capture the room - this is a typical application for condenser or ribbon mikes. Are you using different types of speaker chassis in your guitar cabinet(s)? Or what is the purpose? In any case you need to avoid phase issues between both microphones.

  • Simplification is the way to go in order to understand what is causing the issue.


    Other than that I'm wondering why you want to use two microphones of the same type. What is the value add? Usually people use one microphone to capture the speaker sound closely - this is a typical application for the SM57 - and another to capture the room - this is a typical application for condenser or ribbon mikes. Are you using different types of speaker chassis in your guitar cabinet(s)? Or what is the purpose? In any case you need to avoid phase issues between both microphones.

    A tiny bit off topic but, this following scenario is a situation where you are definitely not avoiding phase issues. Lol………..

    A great purpose for this is to record an SM57 and an AKG 451 (but, it can be two 57’s). Works best with a small condenser and a 57. Both mic’ing a different speaker on a 4x12

    Set the 451 out of phase with the 57. Get a nice scooped balance between both mic’s on this out of phase sound by riding the faders. Think scooped Van Halen 1. Once you find it, Leave the faders right there.

    Put the phase back to normal on the 451.

    Then, send both mic signals together to a mono track in your daw. Record a left and right track of this (in phase).
    Then record a third track (panned central) with the 451 out of phase.
    You end up with a lovely panoramic sound where the centre track still ties the left and right together. But, the centre track now has more space for the kick drum, lead vocal and anything else that is panned central.


    It’s best to sweep the speakers first. Simply put your headphones on and listening to the amp hiss, sweep the mic up, down. Left and right on the first speaker until you hear the most intense hiss. It’s easy to spot where it is. Mark that spot and repeat for the second speaker and mic. Place the mic’s a couple of centimetres off the grill. I am using Marshall 4x12’s for this.


    I am going to make a few profiles like this as it will be so much quicker once I have profiled an amp with both in phase and out of phase sounds to just recall for the next time I use that sound for why the guitars.

    So, it was just a quick tip for a nice full tracked rhythm guitar sound.

  • The point here is that I have "two sounds" in the last profiling stage page (the ones you can compare the original and the profiled):

    A) Original sound, coming from the chain to the Profiler rear input (the one used for profiling purposes). Which sounds the way I WANT it 100%.

    B) Profiled sound, which is what the Profiler did to the A sound. Really different, specially on the low end and dynamics.


    So, if the A sounds perfect, it means that:

    - Amps, mics, cables, I/O converters are fine. Otherwise, this would sound wrong from the very beginning.

    - The problems seems to be during the profiling stage. Where I tried to use less or more buffering/latency, with similar results.

    - I tried to use 48KHz or 96KHz converter settings, just in case that this would be more accurate. But it seems to be the same.


    And regarding MORE THAN ONE MIC, it is always regarding phases. But in a good way. I mean, the phase difference between two (or more) mics can add the magic that you need by natural reasons to your sound. So in this case I am using two SM57 to the same speaker in different angles, plugged to API 512c and Heritage 73Jr (different character). The result is that I am getting less unwanted high frequencies and harsh, and extra body.

  • - The problems seems to be during the profiling stage. Where I tried to use less or more buffering/latency, with similar results.

    Latency seems not to affect the profiling process. I made profiles with a huge amount of latency caused by complex plugins in the DAW. But would be nice to know some in depth here. :)

    - I tried to use 48KHz or 96KHz converter settings, just in case that this would be more accurate. But it seems to be the same.

    This should not have a great effect on the gain.

    Yes, two and more microphones can be nice, if used correctly. But you experience bad results, so you need to simplify to identify the root cause of the issue.

    I also would suggest to start from scratch and add complexity to identify the source of the problem.


    When I profiled several 5150 style amps I always noticed more gain in the Kemper profile as in the original sound. In my opinion this can only be caused by the output signal from the Kemper to the amplifier during the profiling process. I always thought that I sometimes would like to adjust how hot the Kemper will fire the amp during profiling. But I have to add, that it was not a night or day difference and nothing which couldn't fix by pulling down the gain 1-2 ticks or just profile with a bit less gain on the amp.

    I also did several complex profiles through my DAW where I did things like multiple Mics through my analog chains + Amp DI Signal with IRs mixed inside the DAW. And that worked out really good after sorting out the gain staging for the Kemper return.

  • I think Burkhard is right that to get to the root of this, simplifying the process for now might help find where the problem is.
    It would only mean muting one mic just to test.


    How far out is the created Profile from the source? Slightly out or a night and day difference?

    If it’s slight, you can most of the time salvage during Refine. When the Kemper overshoots the gain, bottom and and mids, I normally do some discordant harmonics to get back on track during Refine after adjusting the gain on the Profile to match the source (if the gain has overshot)


    For instance…. During Refine, playing harmonics across all strings..…

    4th fret bottom E, 5th fret on the A string

    4th fret A and 5th fret D

    4th fret D and 5th fret G…..

    Same pattern up all the strings.


    Another harmonic pattern I use is…..

    3rd fret bottom E, 4th Fret A and 5th fret D

    3rd fret A, 4th fret D and 5th fret G

    All the way up the strings.


    I did have a situation where the Profile was completely out and I couldn’t fix it. That was on one of my 70s 50w non master Marshall heads.
    Had the volume on 10 and the resulting profiles were completely freaked out. All muffled bottom end and distorted. Knocked the volume back to 8 on the Marshall and it would the profile fine.

  • I did have a situation where the Profile was completely out and I couldn’t fix it. That was on one of my 70s 50w non master Marshall heads.
    Had the volume on 10 and the resulting profiles were completely freaked out. All muffled bottom end and distorted. Knocked the volume back to 8 on the Marshall and it would the profile fine.

    Great stuff Vinny! I am loving your tips.


    I have said in other places on this site you may get better results when profiling higher gain stuff if:


    - you go with about 20% less gain than you want and dial it in after the profile is made. It may be much harder mathematically to get an accurate profile when it is too distorted. Meaning the profiler may have a harder time calculating and sorting out what makes this amps sound if it is massively distorted.


    - you use less bass than you want on the final profile. It is easy to add bass in after the profiling process. And if you have too much bass the profile ends up with a definition value of 10 which may not sound natural. It may sound thin on the high freq side. It may be better to profile a little thin to begin with then roll back the definition to add fullness/bass to get a more natural amp sound. M.Britt has stated he knows a profile is right when the profile created is close to the default setting of 5.0.


    This is the real beauty of the Kemper. You can tweak the profile so many different ways to get the magic sound you are looking for. Do not limit your thinking. Dual mics? Sure why not! Go nuts! But you should also start simple and work towards nuts so you know what is actually creating the sound and what is hurting it.

  • I think certain power amp distortion can maybe freak the profiling process out. Not sure though.
    Gain wise, I have had no real problems with very high gain sounds from my Mesa Mk3’s, CAE3+SE, ADA MP-1 etc.


    I do find the refine step quite fascinating. Finding ways to bring the Profile back on track when it sometimes takes a left turn while using Refine.

    Also, getting the full range of a high gain sound that reacts to different pick angles and attacks.


    I spend ages refining my profiles but have a few set things that I normally play during that process. Discordant harmonics being one thing. I check everything all over the neck. Sort the bottom end out….. has that changed the top end and mid range. Making sure that the Profile is representative.


    Having no undo, I have developed a few things that can normally get my Profile back if it goes south during a Refine.

  • This is the type of thing I am thinking about when I say too much distortion. Not saying this is what happens because it most likely does not. But a good example of some information being masked out by higher gain harmonics. Having a little less gain may make it easier for the Kemper to get accurate results on the smaller harmonic frequencies, etc.



    I may be completely off in left field somewhere though :wacko: The Kemper ramps up the volume slowly in the profile process so it may check at many different volumes to get a clear picture of all the frequencies. and when the gain kicks in.


    Maybe that is what the Kemper 2 needs? When profiling allow two inputs: one from the preamp and one from the normal input to get the power amp and speaker. Then you could have a VOL knob that alters the sound by adding more power amp distortion.


    Now I am just babbling.