# Baxandall Bass and Tone Circuit and Calculator

In this active Baxandall bass and tone control circuit we need a 20 dB gain with the low frequency upper 3 dB corner at 30 Hz, and high frequency upper 3 dB corner at 10 kHz. In the graph above, we can see where those points are, and the calculator in this part of the article calculates the FLB and FHB points and the necessary values of the components required given some basic parameters to start out with. As these things go, a useful and practical Baxandall circuit usually starts out with defining the poles and zeros as shown in the graph. In order to save time, I have included a calculator for adjusting the values if the nearest component values cannot be found, or it turns out to be too expensive. Once you have the component values, there is also a stripboard build showning how to make one of these circuits for a stereo preamplifier application.

One advantage of this article is that it starts out with the mathematics and works all the way through to a practical circuit with a build layout. If you cannot do the maths, then the default values in the calculator are for a typical circuit for general audio applications, and you can skip the maths altogether.

## Initial Parameters

## Nearest Component Values

Component | Calculated Value | Closest and Cheapest on eBay |

R1 | 11111.11 | 11 kΩ |

R3 | 3679.01 | 3.6 kΩ |

R4 | 367901.23 | 500 kΩ |

C1 | 4.77 *10^-8 | 47 nF |

C3 | 4.33 *10^-9 | 4.7 nF |

Standard Capacitor Values Conversion Chart pF - nF - uF

With the default initial parameters, you can see that the calculated values are reasonable enough to work with, and the nearest values are readily and cheaply available online. The most expensive component tends to be the potentiometer, and ideally you need to set the parameters such that the calculated value of R4 is below 500 kΩ. This is because large value pots in the mega-ohm range tend to be very expensive and difficult to find.

## Full Component List

Type | Part Number | Value | Description |

Resistors | R1 | 11 kΩ | metal-film 1 % |

R2 (Variable) | 100 kΩ | Linear, Ganged | |

R3 | 3.6 kΩ | metal-film 1 % | |

R4 (Variable) | 500 kΩ | Linear, Ganged | |

R5 | 11 kΩ | 5 % | |

R6 | 1 kΩ | 5 % | |

R7 | 47 kΩ | 5 % | |

R8, R9 | 100 kΩ | 5 % | |

Capacitors | C1 | 47 nF | Polyester |

C2 | 1 µF | Electrolytic | |

C3 | 4.7 nF | Ceramic MLC | |

C4 | 1 µF | Electrolytic | |

C5 | 1 µF | Electrolytic | |

Semiconductors | IC1 | LM324N | PDIP |

Misc | Stripboard | 36-strips × 50-holes | 95 mm × 127 mm |

## This Article Continues...

Baxandall Bass and Tone ProjectCircuit and Calculator

Bass and Tone Board Layout

Potentiometer Wiring

Split-Rail Power Supply Circuit

PSU Board Layout

Transformer

Circuit Testing