Opposite of Passive. In the world of music technology passive devices are those things that only subtract elements from a signal. An active device has its own power and can, if necessary, add to or amplify a signal in some way. Active devices have the advantage of being less “lossy” in how they take care of signals and can produce better results under the proper circumstances. The disadvantage to most active devices is that they usually add some amount of noise and distortion to a signal (op amps always add noise and distortion), and may color the sound in ways some passive devices may not. Active devices also tend to be more expensive due to the cost of components and because a power supply is required for them to operate.