Can't dial out some of that compression...

  • yes, but all the characteristics of the power amp signature were captured in the profiling process and are part of the Profile, which makes it necessary for the power amp stage to be as linear as possible to deliver the authentic sound of the amp.

    Yes, those characteristics were captured in the profiling process. The caveat of the linear power amp (especially at higher volumes) is that because it is linear, it doesn't interact nor can it replicate the interaction of a tube power amp and speakers which is what the OP is lacking. The "push and pull dynamics" don't occur. Linear SS power amps into non linear guitar range speakers will always lack this interaction. It's simply the nature of the beast. Kinda like how a germanium fuzz pedal needs to be directly connected to a guitar for it to perform as intended. Put a buffer (a linear device) in between the guitar and fuzz and you lose the interaction, dynamics and the sound is changed. MOre or less the same phenomena.

  • Yes, those characteristics were captured in the profiling process. The caveat of the linear power amp (especially at higher volumes) is that because it is linear, it doesn't interact nor can it replicate the interaction of a tube power amp and speakers which is what the OP is lacking. The "push and pull dynamics" don't occur. Linear SS power amps into non linear guitar range speakers will always lack this interaction. It's simply the nature of the beast. Kinda like how a germanium fuzz pedal needs to be directly connected to a guitar for it to perform as intended. Put a buffer (a linear device) in between the guitar and fuzz and you lose the interaction, dynamics and the sound is changed. MOre or less the same phenomena.

    again, the interaction between power amp and speaker is captured during the profiling and is part of the Profile.

    if you use a tube amp to amplify this, you'll end up with both tube amp signatures in series.

    to get the authentic sound of the profiled amp, a linear solid state power amp should be used.

  • again, the interaction between power amp and speaker is captured during the profiling and is part of the Profile.

    if you use a tube amp to amplify this, you'll end up with both tube amp signatures in series.

    to get the authentic sound of the profiled amp, a linear solid state power amp should be used.

    Don, I totally understand what you are saying and absolutely agree. The OP (and me) weren't talking about sound, we are referring to "feel".

    All I am saying is the effect of the profiled interaction is greatly diminished with a linear power amp feeding guitar speakers. It is impossible for the linear power amp to interact the same way causing the change in feel because the amp isn't reacting. Although the kemper does an admirable job of profiling this interaction IN the profile, because the linear power amp is AFTER the profile, the profiled interaction can be lost to a significant degree.

  • Don, I totally understand what you are saying and absolutely agree. The OP (and me) weren't talking about sound, we are referring to "feel".

    All I am saying is the effect of the profiled interaction is greatly diminished with a linear power amp feeding guitar speakers. It is impossible for the linear power amp to interact the same way causing the change in feel because the amp isn't reacting. Although the kemper does an admirable job of profiling this interaction IN the profile, because the linear power amp is AFTER the profile, the profiled interaction can be lost to a significant degree.

    You’re misunderstanding Don, I think. The push and pull interaction between the speaker and the power amp is captured when making a Direct Amp/Merged profile properly, so that if you played the same riff through both setups, they would react the same, but only with a linear power amp feeding the speaker in the Profiler’s case, otherwise the profile’s push and pull would be magnified by the tube amp’s own push and pull, or perhaps even nullified, if they don’t react in the same way.


    If the OP is using DA/Merged profiles that have been captured correctly (you’d be surprised how many profile makers still don’t know how to do this right), then the cause of his problem must lie elsewhere.

  • The push and pull interaction between the speaker and the power amp is captured when making a Direct Amp/Merged profile

    speaker/poweramp interaction is captured by the profiling process even if you're making a Studio Profile.

    The difference between Studio and Merged Profile is that the separation of amp and cab is completely authentic with a Merged Profile, and determined by an algorithm in a Studio Profile - but that doesn't not mean that it is not present.


    Therefore using a tube power amp will give you an additional power stage signature unless you made a preamp-only Profile (DI Profile).

    I'm not saying that this will sound terrible or even less pleasing, but it can really be no longer called authentic.

  • The caveat of the linear power amp (especially at higher volumes) is that because it is linear, it doesn't interact nor can it replicate the interaction of a tube power amp and speakers which is what the OP is lacking. The "push and pull dynamics" don't occur. Linear SS power amps into non linear guitar range speakers will always lack this interaction. It's simply the nature of the beast.


    I assume this is guessing ?


    What is called "interaction", is exactly captured in the DI profile.

    I don't know who in history brought up that meme of "interaction of tube amp and speaker". But it was then taken over by everybody and abused.

    There is no "push pull dynamics", that don't occur.

    The truth is, that tube power amps interact LESS with the speaker than a SS power amp.

    SS power amps interact heavily in a very determined way.



    Here is the technical background:


    SS power amps as well as class d power amps measure the voltage at the speaker output and compare it to the input signal. Any deviation will be corrected.

    If, e.g. at a certain frequency the output signal is double as high as it is supposed to be, then the input signal is cut in half, to correct the outcome.

    This is called "negative feedback", and reflects the maximum interaction possible. The output impedance of a SS amp is virtually 0 Ohm.


    Tube power amps do not feature this full feedback due to certain reasons, the interactions are limited.

    When the speaker emphasises certain frequencies such as its resonance frequency, then the input signal is not fully corrected and a higher voltage remains in the speaker output.


    When you create a DI profile, then this higher voltage is measured or profiled.

    When you play said profile through a SS amp, than this voltage gets fully compensated by the amp.

    But the higher voltage is played to the power amps input by the profile as well, with then does not get compensated, since it is the input signal and not the negative feedback signal.


    This way, the effects of the lesser interactions of the tube amp are printed into the profile and then reliably played back through the SS amp.


    I hope this was an understandable explaination.

  • Sorry guys...Didn't mean to cause the uproar.... In my particular application, I am running the Kemper Powerhead as just a regular amp pushing a Mesa Recto 4 x12. (I also use it for A LOT of direct recording which it excels and exceeds any and all expectations).. I do not us FRFR , or go through a PA system..This is strictly about live and loud with a band (Hard and heavy- high gain tones)..Other guitar player used a JCM 800 and a Splawn Hotrod through 2 4 x 12 cabs. I sometimes use my Kemper in this situation as the other guitar player...At significantly loud volume (Just through Guitar cab), there is a little bit of compression that occurs on the bounce of the low strings. My OP was just asking how to dial out some of this... It's ok if it's not perfect as the Kemper was not designed to be used this way, although it "allows" me to do it. I am getting plenty of "push & feel" through the guitar cab to remain inspired and sound good. I picked up the Kemper as an "ALL in one" head (Again- live and loud through a guitar cab, not PA or FOH)..I have learned that it will work, but not ideal. That being said, I think I wouldn't mind picking up a Marshall Cab and a little Fender cab (Jensen speaker) just to have to get some of those other classic sounds live. (Kind of like an inefficient /backwards way of using the Kemper). Maybe someday I'l be in a situation where I have to use in ear monitors and the House system, but until then, for live rocking with the band, I'm all about going through a guitar cab.

  • Sorry guys...Didn't mean to cause the uproar.... In my particular application, I am running the Kemper Powerhead as just a regular amp pushing a Mesa Recto 4 x12. (I also use it for A LOT of direct recording which it excels and exceeds any and all expectations).. I do not us FRFR , or go through a PA system..This is strictly about live and loud with a band (Hard and heavy- high gain tones)..Other guitar player used a JCM 800 and a Splawn Hotrod through 2 4 x 12 cabs. I sometimes use my Kemper in this situation as the other guitar player...At significantly loud volume (Just through Guitar cab), there is a little bit of compression that occurs on the bounce of the low strings. My OP was just asking how to dial out some of this... It's ok if it's not perfect as the Kemper was not designed to be used this way, although it "allows" me to do it. I am getting plenty of "push & feel" through the guitar cab to remain inspired and sound good. I picked up the Kemper as an "ALL in one" head (Again- live and loud through a guitar cab, not PA or FOH)..I have learned that it will work, but not ideal. That being said, I think I wouldn't mind picking up a Marshall Cab and a little Fender cab (Jensen speaker) just to have to get some of those other classic sounds live. (Kind of like an inefficient /backwards way of using the Kemper). Maybe someday I'l be in a situation where I have to use in ear monitors and the House system, but until then, for live rocking with the band, I'm all about going through a guitar cab.

    I have tried all of the nicer FRFR cabs out there (Mission, Friedman, etc..) and at lower volumes, they work great..At band volume (at least my band's volume) they sound awful and cannot push air or react like a guitar cab (As they are not designed to do so) I even tried 2 powered Mission cabs, stereo affect was cool, but just sounded like really good stage monitors...which are fine for some folks. Love my Kemper!

  • Enter stage left:


    Kemper Kone.

    Yes..this sounds cool.. I look forward to a multiple speaker set-up like this to compete with a 4 x 12 ... 1 x12 cannot compete ...different volume/wall of sound. I hope this isn't like the Line6 (sorry, please don't be offended Kemper peeps) Power Cab (Mehh.... it's "ok" at lower volumes- sounds weird).

  • It wasn't a guess :) My guess is that I'm not making my point very well, so that's my fault. I completely understand and agree that the "interaction" is captured in the DI profile. That isn't the issue. The issue is trying to replicate that with a SS power amp. With the with the kemper, and any SS power amp, you are essentially reamping a profile of a tube amp rig through a SS power amp and guitars speakers. Since SS and Tube amps do not react in the same manner to speaker loads and impedance changes, the feel(and/or "compression" as stated by the OP) will not be the same. It is impossible to replicate that in this scenario. Simply amplifying that interaction is not the same.

    I personally don't mind this sense of extra compression in the profiles. I find that it is present to varying degrees in all digital amps/modelers. Actually the Kemper does a great job of capturing a lot of nuances that some modelers miss. Assuming the profile is well done, the KPA is great.

  • It wasn't a guess :) My guess is that I'm not making my point very well, so that's my fault. I completely understand and agree that the "interaction" is captured in the DI profile. That isn't the issue. The issue is trying to replicate that with a SS power amp. With the with the kemper, and any SS power amp, you are essentially reamping a profile of a tube amp rig through a SS power amp and guitars speakers. Since SS and Tube amps do not react in the same manner to speaker loads and impedance changes, the feel(and/or "compression" as stated by the OP) will not be the same. It is impossible to replicate that in this scenario. Simply amplifying that interaction is not the same.

    I personally don't mind this sense of extra compression in the profiles. I find that it is present to varying degrees in all digital amps/modelers. Actually the Kemper does a great job of capturing a lot of nuances that some modelers miss. Assuming the profile is well done, the KPA is great.

    Mr Kemper is right. You are wrong. Resonances in a load are a function of frequency, not voltage. This means you can profile this resonance (interaction) provided you’re using the same speaker and the same gain and it theoretically should be able to sound exactly the same. You can profile these resonant points as said, and then the class D power amp can just replicate this. The maths works out.


    When you make a direct profile properly you connect both the speaker and the amp to the DI box, and the kemper monitors the change in voltage as you play and records these resonant points. Now I’m not arguing how well it does this, just that mathematically it can be done.

  • Muudrock, I will try to stay scientific here. There is no such thing like „impedance change“ or "push and pull dynamics" in a power amp connected to a speaker, and no compression resulting from such effect.


    Also there is no difference in sound and feel. What you feel is the sound from the amp. No one has ever presented two sounds that sound equal but feel different. The only exception to this is latency: You can feel different latencies as a player, even when the sound is the same.


    Please post links, if you have different information.


    About compression: A tube power amp can add compression, when it‘s acting in its nonlinear region. But this not directly related to impedances or interactions.

    If compression of the power amp was the issue, than the lack of compression of the SS power amp. But the OP reports the opposite.


    It would be great if we had comparison clips, even from the DI signal without cabinet.

  • Thanks everyone...again, there is more time spent on this discussion than the experience itself. I promise you, there is compression, and it's OK. Again, the sound coming through the guitar cab is about 90 % of the way there... This doesn't need to be solved, or argued about at this point. I bet that a vast majority of people on here wouldn't even have this issue... Again, this is live and loud with the band, high gain, dropped to C tuning... The Kemper works pretty well, just a bit different in the feel on the low strings (Compressed and not quite as dynamic...and this is only a little bit..) I am not going to try to record all of this as I would have to mic up my cab....and it's more of a "feel" thing..

  • Next time you create a profile, please try to refine that note a bit.

    It seems that it pushes the distortion a bit too hard. This is not a matter of the power amp.


    Also try to increase the Definition parameter in the amp section.


    Have you made a studio profile as well?

    Does it suffer from the same effect?

  • Thanks..I have found some success in the Defnition... Studio profiles are stellar..no compression..work as advertised, etc...