In typical carbon film potentiometer, the function is established by sliding a small piece of metal along a rounded carbon disk to control the resistance.
So, there will be noise generated by the mechanical action where the contacting points between the metal piece and the carbon disk sliding against each
other when operating the pot. Also there will be some carbon dust fall off from the disk after a period of usage, which may cause bad contact or fiction
between the contacting points. This will also induce noise.
Although E9 and A1 both use the Alps potentiometer from Japan, it is still very hard to avoid such an issue Unless digital volume control or stepped
attenuator was used.But digital volume control, with the current technology, will cause distortion and increase background noise. With stepped attenuator,
the durability and noise induced by moving mechanical parts are still a real concern, not to mention their high cost.
So the issue is very hard to avoid in principle.
But there are two ways to help to reduce and even avoid such an issue.
- Quickly turning the volume pot back and forth to use the sliding action of the contacting points to clean out the carbon dust
- Disassemble the aluminum volume knob on the potentiometer and spread the pot with electronic cleaning solution (from general electronic store) or pure alcohol. Allow the cleaning agent to penetrate the pot and turn the pot back and forth to clean out the carbon dust and dirt. This usually will fix the problem.
