How to Select the Correct Rheostat for a Speaker Volume Control

By William Kinsey

Some radios use resistors for volume control and others use electronics.
i volume maximum image by nfrPictures from

Speaker volume controls are used to aid in balancing speakers. These are most commonly used with home entertainment systems that are custom-built to match irregular room shapes. Every room has unique harmonics, so the same speakers in two different rooms will sound differently. Speaker volume control resistors are used to help custom set each speaker to match a room's unique harmonics. The sound level from each speaker should be equal at the central listening point.

Identify the maximum output of both voltage and current for each channel of the stereo system. The speaker resistors chosen must be able to handle this power level. For longer life, it is recommended that the resistors have a higher power dissipation rating than the maximum output of the stereo system.

Use a logarithmic resistor rather than a linear resistor. This will allow the change in speaker voltage to follow the speakers' natural response curve. This is important when fine-tuning is the primary goal, rather than just turning the volume down. A logarithmic resistor is more accurate and expensive than a regular linear resistor.

Choose a resistor that goes with the natural theme of the room and does not take up a large amount of space. Since there will be at least one resistor per speaker, smaller is better and easier to hide.