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preamplifier

 
Dictionary: pre·am·pli·fi·er   (prē-ăm'plə-fī'ər) pronunciation
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n.
An electronic circuit or device that detects and strengthens weak signals, as from a radio receiver, for subsequent, more powerful amplification stages.


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Sci-Tech Encyclopedia: Preamplifier
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A voltage amplifier suitable for operation with a low-level input signal. It is intended to be connected to another amplifier with a higher input level. Preamplifiers are necessary when an audio amplifier is to be used with low-output transducers such as magnetic phonograph pickups. A preamplifier may incorporate frequency-correcting networks to compensate for the frequency characteristics of a given input transducer and to make the frequency response of the preamplifier-amplifier combination uniform. See also Amplifier; Voltage amplifier.

Wikipedia: Preamplifier
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"Preamp" redirects here. For the device used in professional audio, see Microphone preamplifier.
An example of a typical high-end stereo preamplifier.

A preamplifier (preamp), or control amp in some parts of the world, is an electronic amplifier which precedes another amplifier to prepare an electronic signal for further amplification or processing. The preamplifier circuitry may or may not be housed as a separate component.

Contents

Description

In general, the function of a preamp is to amplify a low-level signal to line-level. A list of common low-level signal sources would include a pickup, microphone, turntable or other transducer. Equalization and tone control may also be applied.

In a home audio system, the term 'preamplifier' may sometimes be used to describe equipment which merely switches between different line level sources and applies a volume control, so that no actual amplification may be involved. In an audio system, the second amplifier is typically a power amplifier (power amp). The preamplifier provides voltage gain (i.e. from 10 millivolts to 1 volt) but no significant current gain. The power amplifier provides the higher current necessary to drive loudspeakers.

Preamplifiers may be:

  • incorporated into the housing or chassis of the amplifier they feed
  • in a separate housing
  • mounted within or near the signal source, such as a turntable, microphone or musical instrument.

Examples

  • The integrated preamplifier in a foil electret microphone.
  • The first stages of an instrument amplifier.
  • A stand-alone unit for use in live music and recording studio applications.
  • As part of a stand-alone channel strip or channel strip built into an audio mixing desk.
  • A masthead amplifier used with television receiver antenna or a satellite receiver dish.
  • The circuit inside of a hard drive connected to the magnetic heads or the circuit inside of CD/DVD drive which connects to the photodiodes.
  • A switched capacitor circuit used to null the effects of mismatch offset in most CMOS comparator based flash analog to digital converters

See also

External links


This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

 
 

 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Preamplifier".  Read more