Cable Calculator Resistance with three decimals at 20 °C please enter decimal separator as "." Cable properties: Length in m: Diameter: Conductor made of: 0.25 mm20.5 mm20.75 mm21.0 mm21.5 mm22.5 mm24.0 mm26.0 mm210 mm216 mm2 Copper Aluminium Silver Impedance of a single wire cable: Ohm Impedance of a twin wire cable: Ohm Damping Calculator and Power Calculator Damping indicates the amplifier's ability to control the driver's diaphragm. The higher this value, the better. The following parameters are calculated: Your devices: Loudspeaker Impedance: Amplifier Damping Twin wire cable, as indicated above. Ohm x Ohm (if not known keep 800) Damping of the total system: x > 100: excellent, lowest loss >   50: good - adequate for hi-fi >   15: suitable for PA systems >   10: for background music maximum power handling of unrolled cable: Watt Copyright © Iris Strassacker, 2002. All rights reserved - Warranty excluded

How big should the damping factor be?

Opinions differ quite substantially on this point:
• Some DIY enthusiasts are able to hear the difference between 400 and 800 clearly on high quality subwoofers.
• Some experts *) say that a value of more than 20 is unnecessary.

*) E.g. the scientific paper: Damping factor: effects on system response, a technical analysis by Dick Pierce.

So, who is right? What value is desirable? To find out we are discussing both points of view.

From our point of view there is an additional aspect that needs to be considered: measuring the damping factor of a transistor amp is usually done at high outputs (that's a least how Peter Strassacker always used to do it). At low outputs, however, most amplifiers (i.e. low quiescent current transistor amps with push-pull circuit) have a factor that is 5 to 10 time lower.

When buying a conventional amplifier with damping factor of 100, it has to be expected that this value may drop to 20 at low outputs.

The values indicated in the table above take this into consideration.

When using a push-pull circuitry amp with high quiescent current or an amp without push-pull circuit (like many valve amps), then from a scientific point of view a value around 20 is excellent, like proven by Dick Pierce.