Passive Bass and Treble Booster

In most cases, we love to set the bass and treble setting to maximum when listening to music. This gives us a nice sound with bass and treble turned up. Here’s a simple circuit than can be placed at the input of your amplifier to boost the bass and treble. Keep in mind that this circuit is passive, meaning you can’t really boost signal using a passives circuit.

This circuit actually attenuates the mid band frequency, in effect it sounds like you boosted the bass and treble.

This circuit is only applicable for high line level sources like headphone output. If your source output is directly connected to a volume control instead of a buffer circuit, you might not get good result.

R1 and C1 forms a low pass filter. C2 and R2 forms a high pass filter. R3 and R4 is used to combine the output of the high pass and low pass filter. R5 is just a bypass and is used to increase the mid frequency. Because of this configuration, it is really hard to compute for the frequency response so it is easier to just simulate the circuit.

R5 increase the level of the mid frequency so if you want more bass and treble, increase the value of R5 or just remove it. Keep in mind that this will also affect the center frequency so you may also adjust the low pass or high pass filter values.

Increase C1 or R1 for lower bass frequency. Increase C2 or R2 for higher treble frequency. Decrease R3 For higher level of bass or increase R2 to decrease the level of treble.

Simulation Circuit

R6 is added to simulate the output impedance of your source. You might want to add a volume control on the output of input if you have on your actual circuit to be able to have more accurate results.

Frequency Response

Caution and Warnings!

Because it is not using any buffers or op-amps, there are many drawbacks!

  • The frequency response will be  very dependent on the input and output impedance of the circuit it will be connected
  • There is a big signal attenuation, it is only applicable to sources with high level.
  • You should always consider the input impedance of the circuit it will be connected. As much as possible, it should not be connected directly on the volume control, the frequency response will be very different when a volume control is connected to the circuit. Include the volume control on your simulation for more accurate response.