damping factor: The damping factor is the ratio between the impedance of the loudspeaker and the output resistance of the amplifier. A high damping factor mainly affects the bass reproduction, which becomes more controlled, drier and more precise. On the other hand, high damping in the area of the resonant frequency of course also the depth of a system.
Conclusion: The damping factor is a quantity that has an aspect in the relationship between amplifier and loudspeakers.
The damping factor is a dimensionless number, e.g. B. 200. The damping factor represents the resistance ratio of the speaker to the entire circuit.
The circuit consists of:
- them internal resistance of the amplifier
- the cable resistance of the cable from the speaker and back again
- the contact resistance at the respective contacts. This contact resistance should be as small as possible and is therefore usually not taken into account.
- any series resistors in the crossover
- other cables in the box or conductor tracks. The influence of these variables can usually be ignored, otherwise the construction is useless anyway.
- the DC resistance of the voice coil of Chassis
- ultimately the impedance of the voice coil of the chassis
The damping factor now reflects the ratio of the impedance of the driver's voice coil to the sum of all other (power-hungry) components in the circuit.
The higher the damping factor, the better the “yield” and the more Performance can be transported to the speaker.
If an amplifier has an output transformer, i. A. With tube amplifiers, the damping factor is usually small.
Good values are e.g. B. Values from 50, to specify exact limit values, however, is pointless, it depends too much on the tuning of the chassis, whether a damping factor that is too low really has an audible effect or not.
Frequency dependence of the damping factor:
A high damping factor works primarily in the lowest transmission range of a loudspeaker by replacing the voltage generated by the loudspeaker by induction with the lowest possible voltage Resistance short-circuits, i.e. the chassis “brakes” electrically. middle and Tweeter will i. A. far from her natural resonance operated, also tend to generate lower induction voltages, so that the effects here are far less.
Realistic values in this case would be 4 Ohm LS impedance at 0,5 ohm crossover impedance, so the damping factor is already limited to 8 - no matter how much damping factor the amplifier would theoretically have. In this case it is completely sufficient if the amplifier has a theoretical damping factor of approx. 30.
Influence by the coil resistance of the voice coil:
The DC (direct current) resistance of the series coil in the passive one is particularly important to consider when discussing the damping factor Crossover for the bass chassis. Since very large inductances are required, the length of the winding is such Kitchen sink very large (potentially high resistance). In order to keep the resistance low, cheap ferrite core coils are often used (the core material increases the magnetic flux and thus the inductance), but they saturate at high power levels and therefore distort more. Air coils (no core material) are ideal in terms of distortion, but they are extremely large, expensive and have high impedance (such coils for the bass range can weigh several kilos). A compromise are transformer core coils or so-called "zero-ohm coils". These models are very expensive and are practically not used at all in conventional LS; especially the extremely complex zero-ohm coils (extremely low DC resistance) can also saturate at high power levels (distortions).
Damping factor and active boxes:
This consideration only applies to passive speakers - with active speakers any discussion of the damping factor is superfluous, since the manufacturer has installed the amplifier and the chassis in one housing and you cannot measure or influence it, in contrast to passive speakers, you could e.g. B. use a thicker cable.
For the manufacturer of active speakers, however, the problem is quite different: Here the damping factor can have a much greater effect, since the crossover impedance is eliminated and the cable impedance can also be minimized - or to put it another way:
The problem of "what does a high damping factor bring to the final stage, when the resistance of the coil is so huge” clearly speaks for active concepts, at least for the bass range. Here the amplifier is coupled directly to the chassis (only the cable resistance is
relevant), which ensures a much better control of the membrane movement.
For example:
A loudspeaker is 8 ohms, it is connected to an amplifier with an internal resistance of
1 ohm connected. You don't know how the 8 ohms of the speaker are formed because you don't know the crossover. Then you have to calculate: 8 ohms / (1 ohm (for the amplifier) + 1 ohm (for the cable) = 4. The damping factor is 4. That's a bad value.