01/11/2025
Volume inbalance in older Vintage amplifiers
I have been asked what's the reason the left or right side can be lauder in an audio system?
Cause could be because the volume potentiometers tolerance.
Logarithmic Potentiometer also called Audio-Volume Potentiometers mainly used for audio volume control to obtain a more natural linear-perception in sound intensity change when adjusting the volume, because the function of resistance versus angular displacement follows a logarithmic curve, As turn the shaft, the sound intensity seems to increase in a linear manner, even though the actual power variation is logarithmic. To compensate for the ears logarithmic behaviour, Audio Volume potentiometers were developed to improve it, While it is called logarithmic, it is actually an exponential curve. Because the human ear is sensitive to sound intensity in a logarithmic fashion, When running at low sound intensities a small change in intensity, It is perceived as a big change in volume, while at high intensities a large change is required for the same change in perceived volume.
Here is a datasheet for a stereo 100 Kohm potentiometer still made and sold: -tolerance is +/_ 20%
So measuring output can be different too !
