GLOBAL EQ Filter behavior on Main/Monitor OUT

  • Well, I did some tests on the Global OUT EQ of the Kemper to see how the filter works.
    "Trust your ear" is the always valid solution, but I believe that this additional information can be very useful to know, when you have to tweak you Monitor System and/or your PA.
    For sure this will help you to understand what you are doing moving knobs ... ;)
    The graphs are self-explanatory, I just added the main points near them.


    Bass EQ (range -5 +5 equal to -12 +12 dB)
    It is a shelving filter that raise or lower from -12 to +12 dB like in the figure below. It start works under 450-500 Hz. Iin the figure, the mid line is with EQ Bass Flat at “0”, the others snapshot are taken at Bass equal to -5; -2,5; +2,5; +5.
    [Blocked Image: https://dl.dropboxusercontent.com/u/56839802/_EFFECTS%20PATCHES_/_KPA_Files_/KPA%20TEST%20Global%20EQ1%20Bass%20%2B5%20%2B2.5%20Flat%20-2.5%20-5.JPG]


    Middle EQ (range -5 +5 equal to -12 +12 dB)
    It is a band pass filter that raise or lower from -12 to +12 dB on the center frequency like in the figure below. The center Freq seems around 500-600 Hz, it works between 100 Hz and 2,5 kHz, the Q parameter of the filter is very wide, under 0,7. The mid line is with EQ Middle Flat at “0”, the others snapshot are taken at Middle equal to -5; -2,5; +2,5; +5.
    [Blocked Image: https://dl.dropboxusercontent.com/u/56839802/_EFFECTS%20PATCHES_/_KPA_Files_/KPA%20TEST%20Global%20EQ2%20Middle%20%2B5%20%2B2.5%20Flat%20-2.5%20-5.JPG]


    Treble EQ (range -5 +5 equal to -12 +12 dB)
    It is a shelving filter that raise or lower from -12 to +12 dB like in the figure below. It start working above 500 Hz, and, with a very gentle curve, reach the maximum after 2 kHz. The mid line in the graphics is with EQ Treble Flat at “0”, the others snapshot are taken at Treble equal to -2,5 and +2,5 (-6 and + 6 dB).
    [Blocked Image: https://dl.dropboxusercontent.com/u/56839802/_EFFECTS%20PATCHES_/_KPA_Files_/KPA%20TEST%20Global%20EQ3Treble%20%2B2.5%20Flat%20-2.5.JPG]


    Presence EQ (range -5 +5 equal to -12 +12 dB)
    It is a shelving filter that raise or lower from -12 to +12 dB like in the figure below. It start works above 2.000 Hz. The mid line in the graphics is with EQ Presence Flat at “0”, the others snapshot are taken at Presence equal to -2,5 and +2,5 (-6 and + 6 dB).
    [Blocked Image: https://dl.dropboxusercontent.com/u/56839802/_EFFECTS%20PATCHES_/_KPA_Files_/KPA%20TEST%20Global%20EQ4%20Presence%20%2B2.5%20Flat%20-2.5.JPG]

  • Like I've suspected, assuming the output EQ is the same as the amp tonestack, the mid control is set to a low frequency with a low Q, I'd much prefer it were around 800 Hz and with a Q of 0.7. As it stands, the mid control is basically unusable to me since when I raise it it also raises bass by a lot, and I find most of the KPA profiles to have excessive bass already.


    Weird that both presence and treble are shelf filters at different frequencies, I thought presence was a bandpass at around 2.5 kHz or so, good to know. Also if the treble control affects frequencies from 500 Hz IMHO that's way too low. Anyway I'm anxiously waiting for the new tonestacks, I'm definitely not a huge fan of the current one.

  • Like I've suspected, assuming the output EQ is the same as the amp tonestack, the mid control is set to a low frequency with a low Q, I'd much prefer it were around 800 Hz and with a Q of 0.7. As it stands, the mid control is basically unusable to me since when I raise it it also raises bass by a lot, and I find most of the KPA profiles to have excessive bass already.


    Weird that both presence and treble are shelf filters at different frequencies, I thought presence was a bandpass at around 2.5 kHz or so, good to know. Also if the treble control affects frequencies from 500 Hz IMHO that's way too low. Anyway I'm anxiously waiting for the new tonestacks, I'm definitely not a huge fan of the current one.


    many people are fans of the current 'generic' tonestack. (me included)
    instead of worrying about frequencies in hertz, q-values and frequency plots, as always: trust your ears (and don't let your eyes doubt what you hear).
    My ears tell me that I can finetune or drastically alter a profile with the current tonestack very intuitively within seconds.


    Are your monitors rear ported and stand too close to a wall, or much worse, in a corner? Or do they have direct contact (no foam underneath) to a larger object, like a table?
    Is your monitoring position not treated against low-frequency buildup, resonances (bass traps) of the room? (sometimes a comfy armchair in the corner is all it takes) ;)


    All of these conditions could result in a perception of 'excessive bass'.

  • many people are fans of the current 'generic' tonestack. (me included)
    instead of worrying about frequencies in hertz, q-values and frequency plots, as always: trust your ears (and don't let your eyes doubt what you hear).
    My ears tell me that I can finetune or drastically alter a profile with the current tonestack very intuitively within seconds.


    I completely agree on this, let me add something about that... :)
    First of all the graphs I reported here are related ONLY to the Global EQ in the Output section. The behaviour of the Tone Stack, after the amp, are similar but have also some significant differences. I will put the results in the coming days...
    I can in the meanwhile say that I'm a big fan too of the "generic" tone stack, and I believe that it is capable of great and rational changes in the final sound with very few tweaking. And since it is generic, for example, it is correct than it should be not too much "narrow" in bands. At the end we have to consider that it is not more not less than an Equalizer with 4 bands. If we want to add something more on this EQ step, we can simply use the graphics/parametric to be added as single effects, as I often do. But I believe that knowing exactly where it works can help in tweaking. The ears are always the winner as decision-maker but, helped with a good theory behind, they will work faster and better ;)

  • Maurizio, I am trying to update the documentation in the wiKPA online and seeking out more info like this. I see this is particular for the output EQ's. What about the generic tonestack- "First of all the graphs I reported here are related ONLY to the Global EQ in the Output section. The behaviour of the Tone Stack, after the amp, are similar but have also some significant differences. I will put the results in the coming days..."?


    Thanks for any info in advance. :-)

  • Maurizio, I am trying to update the documentation in the wiKPA online and seeking out more info like this. I see this is particular for the output EQ's. What about the generic tonestack- "First of all the graphs I reported here are related ONLY to the Global EQ in the Output section. The behaviour of the Tone Stack, after the amp, are similar but have also some significant differences. I will put the results in the coming days..."?


    Thanks for any info in advance. :-)


    Graphics for the Amp section reported here ;)
    AMP SECTION EQ
    And thanks to you for your great EQ explanation contribution over the WiKPA and on the Forum !!! :thumbup:

  • Thanks to Maurizio for his investigation.


    I really love the current implementation of the AMP EQ tonestack. Please do not change anything about that. But concerning the output EQs, i feel differently. I already told my story about my JBL EONs that really need heavy EQ treatment in order to sound good.
    Yesterday i tried two Yamaha DXR12. Well, they are lightyears ahead of the JBLs, and only need very small tweaks to get there. In fact, the concept of a very broad q factor for the mids is very good because it prevents the sound to become too artificial. Concerning the bass it´s a very different story though. In order to get low end response right for a monitoring system like the DXR you need to work on the frequencies between 70 and 120 Hz. Putting up a parametric EQ at around 80 Hz with a Q of 1 octave really did the job. Awesome sound!!! However, the bass control on the KPA has a huge impact on the low mids. If you want to manage the low end you cannot do it without changing much of your basic sound between 120 and 450 Hz.

  • Maurizio,


    I would never be able to derive the filter frequencies from the plots you have made.
    Have you used white noise for the measurement?


    Here are the correct frequencies of the output EQ (I have posted it in another thread a few weeks ago already, it's no secret):


    Bass Shelf 150 Hz (steep)
    Mid Peak 600 Hz
    Treble Shelf 2400 Hz
    Presence Shelf 10000 Hz


    The Tonestack (EQ in the Stack) is different and softer. There is interaction between the controls, so there are no defined frequencies, that can be announced.



    Let me say an important word, as assumptions like on this thread keeps me busy since quite a time. There were about four threads in the last too weeks where I had to disagree to assumptions made by measurements
    Whenever you try to visualize a sonic behavior in means of scope, waveform display or frequency plot, to derive a deeper interpretation, you are very likely to fail.
    What you see is rarely what you hear. Trust your ears instead!
    It requires an immense knowledge to make qualified measurements and assumptions to derive better information by measurements and watching the results by your eyes, that you can simply hear with your ears.


    In knowledge thereof, I rarely use scopes or analyzers for my developement work, as I have failed to often by interpreting what I saw, even though I probably have the background knowledge needed.
    Instead I use my ears every day.

  • The Tonestack (EQ in the Stack) is different and softer. There is interaction between the controls, so there are no defined frequencies, that can be announced.

    This is really interesting, since I was under the strong impression that the majority of senior users here thought that those controls were independent from each other.


    Anyway... wiKPA'ed :thumbsup:

  • the bass control on the KPA has a huge impact on the low mids. If you want to manage the low end you cannot do it without changing much of your basic sound between 120 and 450 Hz


    This is so true! And verified by ears :)


    There should be more freqs in output EQ -qood starting point could be for example MXR 10-band eq: that is also ment to the hands of guitarists and it works very well.

  • I don't have problems with the presence so much, but there definitely need to be more points in the "meat" of the guitar tone between 150Hz and 3K.


    I don't often use the output EQ since I'm always listening through my CLRs or IEMs, but the amp tonestack works similarly (I realize it's not exact) and it simply cannot cut problem frequencies without removing good ones.


    My QSCK10s a are a perfect example where output EQ would be excellent to fix the midrange but you can't because the Q is too wide. If you boost what needs boosting, you can't also cut what needs cutting from the previous boost.


    Griff