Typical modern solid-state amplifiers with negative feedback tend to have high damping factors, above 50 and sometimes above 150. High damping factors tend to reduce the extent to which a loudspeaker "rings" (undergoes unwanted short-term oscillation after an impulse of power is applied), but the extent to which damping factors higher than about 20 help in this respect is easily overstated; there will be significant effective internal resistance, as well as some resistance and reactance in cross-over networks and speaker cables. Older amplifiers, plus modern triode and even solid-state amplifiers with low negative feedback will tend to have damping factors closer to unity, or even less than 1 (very low damping factor/high output impedance amplifiers approximate current sources).