100kΩ Logarithmic-Taper Potentiometer
A higher-resistance, logarithmic-taper potentiometer built specifically for audio volume control, where the non-proportional resistance curve is chosen to match how loudness is perceived, not to measure position.
How this component works
A potentiometer (often called a "pot") is a three-terminal variable resistor. It contains a resistive track and a conductive wiper that slides along the track when you turn the knob. The resistance between the two outer terminals is fixed, but the resistance between the middle wiper and the outer terminals changes as the wiper moves.
When all three terminals are used, it acts as a variable voltage divider, perfect for volume controls or setting reference voltages. If you only connect the wiper and one outer terminal, it acts as a simple variable resistor (rheostat) to control current.
Deep Dive: 100kΩ Pot (Log/Audio)
This entry's logarithmic taper exists to correct a mismatch between physics and perception. A linear-taper pot changes resistance proportionally with rotation, but human hearing follows something closer to a logarithmic (decibel-based) loudness scale, meaning a linear pot used for volume would concentrate almost all of the audible change into a small arc of rotation near one end, with the rest of the sweep feeling like it does very little. A logarithmic-taper pot deliberately shapes its resistance curve to counteract this, so equal amounts of knob rotation feel like roughly equal steps in perceived loudness — a psychoacoustic correction, not an electrical optimization.
The 100kΩ value is a separate, complementary choice: in an audio signal path, the pot isn't expected to carry meaningful current, only to divide voltage, so a higher resistance minimizes the loading effect it has on the source stage feeding it and keeps any current draw (and associated power loss) very low. This is a different set of priorities from the 10kΩ linear pot in this category, which is optimized instead for accurate voltage-divider readings into a high-impedance ADC — the same general potentiometer mechanism, but tuned in opposite directions for two genuinely different jobs.
Common Use Cases
- Volume control knob in an audio amplifier or guitar pedal, where log taper matches perceived loudness to knob rotation
- Tone or gain control in an audio circuit where a natural-feeling sweep matters more than linear proportionality
- Signal-source loading control where a higher resistance value is preferred to minimize loading on the upstream audio signal
Frequently Asked Questions
Why does a volume knob use a logarithmic-taper potentiometer instead of linear?
Human hearing perceives loudness roughly logarithmically, not linearly. A linear-taper pot would make most of the audible volume change happen in a tiny arc near one end of rotation, feeling like "nothing happens, then it's suddenly loud." A log-taper pot compensates for that so the knob feels like it changes volume evenly across its rotation.
Why 100kΩ rather than 10kΩ for this audio application?
A higher resistance value reduces the loading a volume pot places on the audio signal source feeding it, and keeps current draw (and therefore power dissipated) very low — both desirable in a signal-level audio path where the pot isn't meant to carry meaningful current, only to divide voltage.
Could I use this 100kΩ log pot as a sensor input for a microcontroller instead?
It would still function electrically, but the logarithmic taper means the ADC reading would not track physical position proportionally, making it a poor choice for position-sensing — the 10kΩ linear-taper entry in this category is the better fit for that job.
Comparison Notes
Where the 10kΩ linear entry is optimized for accurate, proportional position measurement into a microcontroller, this part's higher resistance and logarithmic taper are chosen to suit human hearing and minimize loading on an audio signal path — the two are not generally interchangeable despite both being "just a potentiometer."