ABSTRACT
The job of a balance control on a preamplifier is to adjust the relative gain of the left and right channels and so alter the position of the stereo image to the left or right and do nothing else at all. Anti-clockwise movement of the control is required to introduce attenuation into the right channel and shift the sound image to the left. Some preamplifier designs have attempted to evade the whole balance control problem by having separate but concentric volume knobs for left and right channels. An active balance control is configured so that it makes a small adjustment to the gain of each channel rather than introducing attenuation, so that any noise/headroom compromise can be avoided altogether. A balance control implemented with a pot is subject to inaccuracy due the loose tolerances of the pot track (20%) compared with the fixed resistors around it.
