Good Day,

Can I know how bass and treble can be controlled using an op-amp? I have googled for several solutions but it shows some really complex designs which I don't get.

From my understanding, an Active High Pass filter is a treble booster, while an active low pass filter is a bass booster? Is the basics of it that?

  • \$\begingroup\$ Can you provide a link to the "complex" designs you have seen so we understand your limitations in this area. This way we might have a better chance of explaining the method used so that you are more confident about using it. EJP's answer is the "normal" way of doing it by the way and if this seems too complex then maybe we can offer something that "appears" simpler but in fact does the same thing such as independent bass and treble control that share the same input and are mixed together at the output. Might be easier to understand this for you? \$\endgroup\$
    – Andy aka
    Mar 23, 2013 at 13:37
  • \$\begingroup\$ Well for starts, I am studying computer engineering and we have just been only introduced to various circuit designs. i have only learnt about simple bjt and mosfet amplifers in the past as far as EE content goes. This is why the circuits seem complex to me \$\endgroup\$
    – Raaj
    Mar 23, 2013 at 14:57
  • \$\begingroup\$ this is a good article on tone controls and provides the simplest baxandall circuit there is: learnabout-electronics.org/Amplifiers/amplifiers42.php \$\endgroup\$
    – Andy aka
    Mar 23, 2013 at 21:46

2 Answers 2


Keep googling for the Baxandall tone control circuit. That's the standard solution since 1953. Very elegant, very simple.


The basics of it would be using Two (or Three) Pass Filters (High, Low, Band-Pass for mid range), followed by an amp or control stage, then summed back together at the output.

Some circuits are simple, like the Baxandall, which only uses a op amp to sum the signals back together, while others use an op amp at each frequency, and sum it back with a fourth.

For example:

enter image description here

As for your question From my understanding, an Active High Pass filter is a treble booster, while an active low pass filter is a bass booster? Is the basics of it that?, that is not correct. A (active or passive) Pass filter only does what it says. It Passes and Filters a signal. A High Pass filter lets High Frequencies through while blocking the rest. A Low Pass does the same for Low Frequencies. And a Band Pass is simply a combination of the two, allowing a mid range of frequencies through. You still need a control or amp stage to boost or cut down those frequencies, and a summing stage to put them back together.

  • \$\begingroup\$ The Baxandall tone control circuit uses an opamp to provide a negative feedback signal. It's not just a summing node. And it relies on a low source impedance so the usual realization is between two op-amps. \$\endgroup\$
    – user207421
    Jul 18, 2016 at 6:47

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