Tsukure Studio Simple Audio Tone Controller

This very simple passive circuit provides a simple audio shaping function. At the center of its range, its response is flat across the audio spectrum. 

Adjusted away from center in one direction, it boosts signals above 1 kHz while attenuating those below 1 kHz. Adjusted in the opposite direction, vice-versa.

The circuit needs to be driven by a low-impedance stage, something 100Ω or less, and followed by a high-impedance stage, 250kΩ or more. Since it produces a flat 6 dB insertion loss at the tone control's center position, it would make sense to follow this with a high-impedance op amp based gain stage providing at least the recovery of the 6 dB.

For the 300-3300 Hz audio bandwidth of typical ham systems, at the extreme positions of the control it provides about 5.5 dB of boost and about 6 dB of cut.

Much more complex audio processing circuits are frequently used, but this has a low parts count supported by typical junk boxes. You could scale this design by multiplying all resistor values by a common factor while dividing all capacitor values by that same factor (with some slop to use standard values). For example, 100Ω and 1800Ω resistors and 0.1 uF capacitors.

With lower resistor values you will need even an input stage with an even lower impedance. One simple rule of thumb would be to keep the impedance of the driving stage below half that of the smaller resistor value, and the impedance of the following stage above half that of the variable resistor.

Components used in this module...

Find out more about the components used in this STEM Module.

Let's Get Started!

Below you will find a list of bits to gather before hand, followed by a detailed schematic. Using a breadboard lay out the components and connect them together as shown. Alternatively you can purchase this module from our shop and simply solder the components in the places indicated on the quality assured printed circuit boards provided.

What You Need...

2 47 (47pF / 0.047nF) Capacitor (Ceramic)
2 PCB Mount 2-Pin Screw Terminal Block Connector (Other)
2 200R
[ Red, Black, Black, Black ]
Resistor (0.25 Watt)
2 3K6
[ Orange, Blue, Black, Brown ]
Resistor (0.25 Watt)
1 50K Resistor (Potentiometer / Variable)

NB: Any resistor colour codes specified relate to 5 band resistor codes, the 5th band has not been shown intentionally. The 5th band indicates the resistor tolerence, we use only the highest tolerence resistors in our products.

Take a Closer Look!

Sharing is Caring!

If you like this project, or maybe, know someone else that might, why not click the buttons below to share the experience!

Get Involved!

We are building an international community of engineers, programmers, builders, makers, nerds and geeks, join in below. Ask questions about this module or perhaps share your projects and show others how you have used this information to do something kool!

Tsukure TV

We will be launching the Tsukure TV YouTube Channel very soon! Subscribe now so that you don't miss out on the BIG LAUNCH!

Just An Idea!

This project is currently just an idea, a prototype! This is how we begin our journey of discovery and welcome you to join us.

Why not have a go at making this idea into a working project.


Product Suggestions

If you like this module, why not take at look at one of these awesome products;

Tsukure Studio - Electronic Piano

STEM Ranges

Additional Resources


Our team of engineers and coders have been busy building our own resources to allow us to improve our workflow. You too can have these resources at your disposal.


Useful Links