Can't get my profiles close enough

    I'm having some trouble with profiling and I was hoping someone could give me some pointers on how to improve.

    My main issue is that the low-end doesn't sound right at all. The Kemper sounds high-passed and palm mutes don't translate well. I also noticed that right after profiling, the Kemper profile is noticably quieter than the reference amp signal. After refining, they are closer in level but during refining I can basically hear the mids getting louder but the low-end seems to stay put.

    I made a few samples where I'm switching back and forth - Kemper first, then reference - to show what I mean (tuned in drop C so I could play with one hand - I normally play in D). First up is my JCM800 -> Mesa cab -> single SM57. As you will notice, right after profiling the difference is quite big between the Kemper and the reference. After refining it's much closer, but pay attention to the low-end:

    https://dl.dropboxusercontent.com/u/8687414/Kemp…_pre-refine.wav
    https://dl.dropboxusercontent.com/u/8687414/Kemp…post-refine.wav

    Next is my Orange Dual Terror, and here is where I really can't get it to work properly. Right after profiling, the difference in level is very noticable. After refining, again it's much closer but the low-end is just so much weaker. It also breaks up in a very different way, kind of "uniform" vs "non-linear" in lack of a better description.

    https://dl.dropboxusercontent.com/u/8687414/Kemp…_pre-refine.wav
    https://dl.dropboxusercontent.com/u/8687414/Kemp…post-refine.wav

    I've tried a few things already. Tried with an external mic-pre, tried with mic directly into the Kemper. Same result. Tried changing a few parameters in the "Amplifier" section of the stack to make it break up better but couldn't get it closer. Tried adding some bass in the tone stack but it's not the same; the palm mutes don't react the same either way.

    Any tips on what more I can try to get closer? Especially with the Orange amp - or is that one just really difficult to profile?

    I made similar experience with my profiling attempts in terms of "low end". I usually could fix that quite easily by adding some bass afterwards.

    MJT Strats / PRS Guitars / Many DIY Guitars -- Kemper Profiler Rack / Kemper Remote / InEar

    I think the JMC is as close as it can get.
    It took me a few seconds to hear the difference even.
    This can be corrected by adding one or a half a decibel in the bass region.

    But the question is: Could you tell A or B after you left the studio for 10 minutes?

    The Orange is worse.
    Did you push the power amp hard?

    Quote from ckemper

    I think the JMC is as close as it can get.
    It took me a few seconds to hear the difference even.
    This can be corrected by adding one or a half a decibel in the bass region.

    But the question is: Could you tell A or B after you left the studio for 10 minutes?

    The Orange is worse.
    Did you push the power amp hard?


    I agree that the JCM800 is very close. I've also used a profile with the same setup for an album earlier this year and it worked really well.

    If I could tell which is which after leaving the studio, well my answer would have to be: it depends. If I'm listening on the monitors with lazy ears I think it sounds pretty damn close. If I listen on headphones I can clearly hear the difference, the low-end just isn't there. On open chords - not a huge difference. On palm mutes - big difference.

    The Orange is driven pretty hard, not extreme but pretty hard. I suspected that that might be the problem.

    What troubles me though is that it captures some things really well, but the low-end is a different story. I tried with two amps and it was the same problem with both. I can try a few more but I suspect I'll have the same problem.

    I'm not trying to bash the product or anything, I love my Kemper. I just wonder about if I'm in a situation where I want to fix up a part that was recorded earlier and where I have taken a profile. If I recorded with the Kemper, no problem. If I recorded with an amp, I wouldn't want to replace it with the profiled signal because the low-end would sound very different. Sure I could add a bit of low-end with EQ, although as described it's not really the same. But wouldn't it make sense if the Kemper simply captured that "right" in the first place?

    I've been through a long profiling session today with an Engl Invader and a couple of different cabs and mics, and it does seem like the profiler isn't as... accurate? in the really low regions. Same thing as with your JCM.
    I could spot the differences fairly easily, though i'm not sure i'd be bothered with it in a mix context.
    However, it's always the same inaccuracy - it skimps a little on the sub-bass. The boominess that comes from cab resonance around the fundamental always seems a little compressed or perhaps even phased.

    Depending on the amp, this can be improved by upping the power sag bit. I usually do it before i refine because someone once claimed that changing the settings pre-refine makes for a more fitting refining process - and frankly, we don't know anything about the process so it's all the same voodoo to me.
    Also, refining for a while with the neck pickup seemed to help the Engl. Maybe it'll work for you as well.

    "But dignity is difficult to maintain
    stamina requires constant upkeep
    repetition is boring
    and you pay for grace."

    Quote from Quitty

    However, it's always the same inaccuracy - it skimps a little on the sub-bass.


    Exactly! That's my point. It feels like there's a HPF engaged. I wouldn't even say sub bass, it's higher up than that as well. Guess I'll measure it some day if I feel a bit bored.

    I understand perfectly that the Kemper can't capture the sound to the very last detail, but when it consistently has the same problem then I'm leaning towards calling it a design flaw. I thought I was doing something wrong at first but it seems like I'm not alone at least. If anything can be done to improve this in the future, that'd be greatly appreciated!

    I'll try the power sag thing that you suggested and see if it makes any difference for me. I've fiddled with that setting before and it made very little difference for me then, but I never tried it while refining.

    I had those effects only a few number of times. I also think it has to do something with the way you refine. I ended up strumming all six strings at maximum power on the bridge pickup without using the left hand and without playing palm mutes for about 30 seconds. This normally gives me good results. I might just have been my imagination but when i really PLAY the guitar when refining i sometimes think my results are more off.

    Quote from ckemper

    Refine in the region where you think it's required the most.
    In your case do palm mutes.

    With palm mutes that actually seems to make it worse. Actually like tylerhb describes, just strumming open strings often get me closer. But I'm still lacking the low end...

    I made some tests with EQ yesterday, I'll try it some more today and post my results. I was a bit surprised by what I found actually. What I get is not a HPF on the Kemper signal at all. It actually has MORE subs, BUT it lacks some dBs around 100-120Hz.

    Alright, some further testing done. I recorded some DIs this time to make the test more accurate. I tried some different things, increased power sagging before refining, played dissonant chords, open strings, palm mutes... The results were practically the same though. What I found was that one specific EQ curve always made the profile get closer. I'll need to try this on different cabs and amp settings before I can draw any conclusions (and I have a studio to run unfortunately, hehe), but here are my findings so far:

    Captured the frequency curves with Ozone; blue line is the amp, yellow line is the Kemper profile:

    [Blocked Image: https://dl.dropboxusercontent.com/u/8687414/Kempertest/kemper_curves.JPG] 
    As you can see the Kemper has much more stuff going on under around 90Hz. It's also lacking in the 100-200Hz region. Some discrepancies around 600-1500Hz but it's not as noticeable.

    I applied this curve to the Kemper signal afterwards:

    [Blocked Image: https://dl.dropboxusercontent.com/u/8687414/Kempertest/kemper_eq.JPG]

    The result comes much closer. Not all the way but much closer. The Orange still breaks up very differently but I guess that's because I'm driving the tubes hard. Difficult to capture, I get that. With the Marshall it's much closer.

    Now, you might want to say "so just apply that EQ setting then". Indeed, if I'm in the studio working with a DAW, fine. But if this discrepancy is consistent for all profiling (I'll need to run some more test, as I said) it would be great if it could be applied on the Kemper side already.

    EDIT: Ok, couldn't help myself. :) I ran one more test. Different amp (5150), different cab (1960BX), different mic (MD421). The result:

    [Blocked Image: https://dl.dropboxusercontent.com/u/8687414/Kempertest/kemper_curves2.jpg]

    Looks familiar? I then applied the exact same EQ setting as above. Still, not exactly the same, but MUCH closer. Hell, as far as I'm concerned - let's say the Kemper had one more feature in the profiling options like "Clean up low-end". In that case the profiling could stay the same as before, people would get the same results if they don't engage that function. How about that?

    Edited once, last by tgs (July 11, 2013 at 11:20 AM).

    A huge thanks for that, i'll give it a go.

    That's actually pretty radical... That's a, what, +3dB boost @ 160Hz?
    Normally, i'd call something like that bad EQ judgement.
    I wonder if i can disprove you, though - profile a high-gain amp that doesn't need this.

    Have you tried refining without playing any low notes at all?

    "But dignity is difficult to maintain
    stamina requires constant upkeep
    repetition is boring
    and you pay for grace."

    Quote from Quitty

    Have you tried refining without playing any low notes at all?


    Yes I have. Unfortunately I didn't have time to be as thorough as I wanted, but I tried a few different things:
    * Only open strings
    * Only palm mutes
    * Only dissonant chords
    * Dissonant chords + palm mutes

    In all cases, the results were very similar.

    Quote from crankyrayhanky

    Interesting eq curves...I assume you have & tried different amps (3+)? I found some amps profile much better than others
    With so many variables, I'd like see a 2nd person with ozone try to repeat this procedure


    3 amps so far, two cabs with different mics. I'll try some more when I have time. I totally agree that different amps profile better. But it's the low end response issue that seems to be the same regardless.

    Does the room your Profiling your amp in have issues in regards to these frequency area's? If you hare sampling in a part of the room where there is a higher cancellation of these frequencies...you'll see a skewed response in the bass region but reaching up to 200-300 hz.

    Quote from Jeffsco

    Does the room your Profiling your amp in have issues in regards to these frequency area's? If you hare sampling in a part of the room where there is a higher cancellation of these frequencies...you'll see a skewed response in the bass region but reaching up to 200-300 hz.


    It's a quite well-tuned room, but it could still be a factor. Would be great if more people could do the same kind of test so we can compare the results. Still, why would the Kemper profile add so much stuff in the sub region, that really doesn't make sense to me.

    EDIT: I'll try to profile a PSA-1.1 later tonight if I have time. If it's still the same problem then it's something fishy going on...

    Because at that exact spot in the room...there IS more of that frequency due to a buildup of sound waves at that frequency. You need a signficant amount of bass trapping to level out Sub Bass issues. You'll get Peaks and nulls throughout the room. I'd suggest moving the amp and mic to another part of the room and profile it again. See if the frequency response doesn't change. If it does change...you know it's just a room anomaly due to the peaks and/or Null at that frequency and not the Kemper

    Quote from Jeffsco

    Because at that exact spot in the room...there IS more of that frequency due to a buildup of sound waves at that frequency. You need a signficant amount of bass trapping to level out Sub Bass issues. You'll get Peaks and nulls throughout the room. I'd suggest moving the amp and mic to another part of the room and profile it again. See if the frequency response doesn't change. If it does change...you know it's just a room anomaly due to the peaks and/or Null at that frequency and not the Kemper


    Ok, to clarify: in the first test it was a Mesa cab in one part of the room. In the second test it was a 1960BX in a different part of the room. Same result.

    Some more tests done. Moved cab to different room: same result. Turned down the volume a lot to drive the power tubes less and try to get less room influence: same result, in both rooms. Hmmm...

    Here's the kicker though: Tried with the PSA-1.1. The result was MUCH closer, practically identical.