AMP EQ Curve Characteristics Information

  • i’m not an expert on this stuff by any stretch of the imagination as my approach has always been Guitar into Amp with no (or at least minimal) efects in the chain so while I know a bit of theory I general don’t personal suffer the option anxiety you face. However, here are a few pointers.


    regarding the guitar tone pot - it is practically out of the circuit (spigot fully open) at 10 and is applying max attention at 0. It works by rolling off high frequencies by sending them to ground using a capacitor. The value of the capacitor determines which frequencies get rolled off.

    Tone controls on a regular valve amp also work by reducing the amount of a frequency being send to the next stage. They can never boost a frequency. Therefore, your spigot fully open analogy occurs with all controls as 10. There is a common misconception that setting all controls at 5 is flat. This is far from the truth. No guitar amp has a flat response at any tone setting. They all have a scoop in the mid range. The question is only how severe that scoop is. For example the closest you can get a Mesa Dual Rectifier to flat is something like Bass 0, Mid 10 Treble 2. I can’t remember the exact values but you can check them on the Duncan Amps tone stack calculator. The Kemper tone controls are totally different and work like an active tone stack wehere you can both cut and boost frequencies so 0 is flat in Kemper land -5 is full cut and +5 is full boost.


    The position the tone control in relation to gain stages (distortion to us guitar players) makes a huge difference. If you attenuate a frequency before the distortion stages it will affect the tone and the amount of distortion. It will alter how much certain frequencies are distorted. It will have relatively little effect on the overall tone but will change the distortion character considerably. This is why Mesa Mark series amps with the tone stack before the gain stages are usually set with the bas close to 0 as it stops the distortion getting flubby and farty. If you alter the tone after the gain stages it will have a much more dramat Effect on the tonal change but will not alter the distortion characteristics.


    i hope that is of some help. I’m sure others with more knowledge will be able to add more.

  • Any chance you could fix the broken links?

    Kemper PowerRack |Kemper Stage| Rivera 4x12 V30 cab | Yamaha DXR10 pair | UA Apollo Twin Duo | Adam A7X | Cubase DAW
    Fender Telecaster 62 re-issue chambered mahogany | Kramer! (1988 or so...) | Gibson Les Paul R7 | Fender Stratocaster HBS-1 Classic Relic Custom Shop | LTD EC-1000 Evertune | 1988 Desert Yellow JEM

  • And here's the graph for Low Cut and High Cut in the Output section.

    Corner frequencies in this graph are Low Cut @ 120Hz and High Cut @ 5000Hz

    That’s some pretty soft cut curves. But very “cab like” so i guess that’s a good thing.

    And in the end, the love you take is equal to the love you make.

  • That’s some pretty soft cut curves. But very “cab like” so i guess that’s a good thing.

    I'm not sure what you mean by "cab like"? Cab frequency responses are typically not so well-behaved. Cab responses tend to have resonant peaks and even some comb filter response. These plots look like very typical 2nd order filters with 40db/decade rolloff. This is exactly what one would expect for cut filters. Thanks for the plots by the way.