An attenuator is an electronic device that reduces the amplitude or power of a signal without appreciably distorting its waveform. Attenuators are usually passive devices made from resistors. The degree of attenuation may be fixed, continuously adjustable, or incrementally adjustable.

An attenuator is effectively the opposite of an amplifier, though the two work by different methods. While an amplifier provides gain, an attenuator provides loss, or negative gain.

A fixed electrical attenuator is often called a pad, especially in telephony and audio engineering. The input and output impedances of an electrical attenuator are usually matched to the impedances of the signal source and load, respectively.

In audio electronics, attenuators are used to reduce the output volume of an audio amplifier (e.g. a guitar amplifier). These attenuators can be either resistive or reactive thus reducing the power of the signal.

These devices use electrical resistance to reduce the amplitude of the signal that reaches the speaker, reducing the volume of the output. The original Altair Attenuator was purely resistive. Other models add some electrical inductance or capacitance to the electrical load (including fans, light bulbs and coils). There is debate about whether reactive attenuators do a better job of preserving an amplifier's tone. These devices can also output a line-level signal that can be recorded directly or reamplified through a larger or smaller amp for more or less volume. Use of an attenuator can potentially damage an amplifier. Some production attenuators are the Marshall Power Break, the THD Hot Plate, and the Power Soak.

External links

• Guitar amp power attenuator FAQ
• Basic attenuator circuits

electronics | audio engineering

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