Damping Factor

The impedance of the speaker will also affect what is known as the "damping factor". This is defined as the ratio of the impedance of the speaker to the output impedance of the amplifier. Thus, if the speaker impedance is 8 Ohms, and the amplifier output impedance is 0.05 Ohms, then the damping factor is 8 divided by 0.05 = 160. High damping factors usually mean that the bass response will be well defined ("tight"), whereas a low damping factor will result in a loose sounding bass. Tight or loose bass is from an amplifier is not a matter of preference. A low damping factor on an amplifier implies a high output impedance, which means that the frequency response of the amp can change by reacting to the changing impedance of the speaker it drives, making results unreliable. The bass is just one area that might suffer from a low damping factor, as it can also adversely affect other frequencies where a speaker's impedance isn't flat. Some tube amplifiers may have low damping factors, for example, 10, compared to solid state, which may contribute to their typically loose bass response (tube amplifiers are often described in terms of "warmth" or "looseness", and it can be a very pleasant effect). Such an effect may be very pleasurable, but it's also a good guarantee that you're not hearing what the loudspeaker designer created. In any case, the specification sheet for the amplifier will sometimes list the damping factor, but so long as it's above 70 or so, it's not really a real world issue.