Calculate audio damping factor from amplifier output resistance and load impedance, or estimate system damping factor with speaker cable effects.
Damping Factor Formula
The following formula is used to calculate the damping factor:
Variables:
- DF is the damping factor (unitless)
- R is the amplifierโs output impedance (output resistance) (ohms)
- Z is the speaker/load impedance (ohms)
To calculate the damping factor, divide the speaker/load impedance (Z) by the amplifierโs output impedance (R).
What is a Damping Factor?
Audio damping factor is the load-to-source impedance ratio under stated frequency and load conditions. This calculator uses scalar resistive values or impedance magnitudes, not a complex-impedance model. In system mode, it estimates amplifier output resistance from the specification reference load divided by its damping factor, adds round-trip cable resistance, and divides nominal speaker impedance by that total. Copper values are approximate at 20 ยฐC; the CCA option assumes 1.47 times copper resistance, which is not universal. Damping factor alone does not establish sound quality or audibility.
How to Calculate Damping Factor?
The following steps outline how to calculate the Damping Factor.
- First, determine the amplifierโs output impedance (output resistance) (R) in ohms.
- Next, determine the impedance of the speaker/load (Z) in ohms.
- Use the formula from above: DF = Z / R.
- Finally, calculate the Damping Factor (DF).
- Choose the appropriate solve-for mode and enter the known quantities. For system mode, verify the manufacturerโs reference load; a blank or zero cable length excludes cable resistance.
Example Problem:
Use the following variables as an example problem to test your knowledge.
Amplifier output impedance (R) = 0.08 ohms
Impedance of the speaker/load (Z) = 8 ohms
