Key Difference – Distortion vs Overdrive
Distortion and overdrive are two technical terms which are used in many fields and the key difference between Distortion and Overdrive is that the overdrive is a type of distortion. Distortion is a vast topic compared to overdrive. Sometimes, they appear individually. In optics, distortion is referred to as the alteration of the original shape of an image. Some automobiles have an overdrive unit to achieve maximum fuel efficiency with a reduced engine speed. But, in this article we are using the two terms distortion and overdrive in relation to the waveforms. To emphasize the difference between Distortion and Overdrive, a waveform is put forward.
What is Distortion?
Distortion is the exclusion from the original waveform in the reproduction process. In common usage ‘distortion’ refers to many deviations from the original. Distortion includes non-linear output amplitudes, extra overtones, non-flat frequency response, phase shifts and variations in phase velocity. To overcome some of these effects, engineers use equalizers. In music, distortion can destroy the music quality as well as induce extra quality. In telecommunication and audio video post editing, it is useful to analyze how the distortion is introduced to the signal since the signal processing is needed to remove variations. Distortion is harmful to data transmission. Engineers always try to eliminate distortion, while musicians use the same daemon as a musical effect. Many rock, heavy metal genre guitarists use distorted strings to spice the music.
What is Overdrive?
Overdrive usually takes place when an amplifier is used to amplify a signal exceeding its maximum gain. The origin of the term Overdrive comes from valve amplifier characteristics. First generation valve amplifiers were not much reliable and often produced distorted signals on and beyond their maximum gain. Valve amplifiers too have a maximum gain for a signal just like any other amplifier. When we try to increase the sound level beyond that limit, it leads to saturation (overdrive) of the valves of the amplifier. The result is the clipping the signal.
As seen as in the above figure, the signal is expected to amplify beyond the threshold level. The output signal is limited to the orange area since saturation has taken place. The larger the amplification (gain) expected, larger the distortion that take place. No matter how much gain is expected, the output signal clips at the threshold level. The increase in original waveform results in more and more alterations from the original.
Sometimes the clipping might convert the original signal into a square wave. It’s termed as hard clipping. Many classical distortion/overdrive pedals are replaced by modern semiconductor circuitry.
What is the difference between Distortion and Overdrive?
Definition of Distortion and Overdrive
Distortion: Distortion is the exclusion from the original waveform in the reproduction process.
Overdrive: Overdrive is a sign of exceeding maximum gain.
Characteristics of Distortion and Overdrive
Distortion: Distortion is a vast topic and has many varieties such as preamplifier distortion, power amplifier distortion, power supply sag and output transformer distortion.
Overdrive: Overdrive is a branch of distortion.
Image Courtesy:“Clipping waveform” by Clipping_compared_to_limiting.svg: Iainfderivative work: Mikhail Ryazanov – This file was derived from: Clipping compared to limiting.svg:. (CC BY 3.0) via Wikimedia Commons “Boss turbopedal used” by Dhscommtech (talk) – Own work. (CC BY-SA 3.0) via Commons