What Is an in-Line Amplifier?

K'Lee Banks

An amplifier, often called simply an “amp,” is a specially designed device used for increasing the power and volume of a signal, usually in audio applications, such as in boosting the volume of speakers. The in-line amplifier provides the same results as a solid-state amplifier, offering an improved signal, but typically at a significantly lower cost and without taking up as much room. For instance, one can take an in-line amplifier, plug it in between the receiver and headphones, and enjoy the same sound at a slightly louder volume. Occasionally, home stereo systems simply are not loud enough for their owners, but the addition of stereo amplifiers makes these systems much louder.

An in-line TV amplifier helps boost the digital signal received by a television from over-the-air broadcasts.
An in-line TV amplifier helps boost the digital signal received by a television from over-the-air broadcasts.

Solid-state amplifiers tend to be bulkier, generally have a rectangular box shape, and require a significant amount of floor and/or wall space. In contrast, an in-line amplifier simply connects between one’s headphones and a common stereo receiver. Typically, the design of in-line amplifiers requires little space, yet performs the same and accomplishes the same results as the solid-state amplifier. If the sound output is not satisfactory, a user can simply plug his or her headphones into one side of the amplifier, as well as to the other end of the receiver where the headphones would normally plug in. The end result is simply a louder volume, without bulky components getting in the way.

Nearly any time and place in which a signal transmits through cables or wires, an in-line amplifier is available to boost that signal. There are amplifier kits, as well as a multitude of amplifier parts available to meet most common applications. Generally, most in-line amplifiers have very few parts and are purposely designed to be quite simple to use. An in-line amplifier is constructed in such a way that — provided one has purchased the correct type of amplifier for the appropriate signal — it will function as soon as it is plugged in. In other words, an audio amplifier may not work very well on video signals, as the major goal in the latter case is to improve the quality and intensity of light.

People may choose from many different types of amplifiers, depending on their intended use. In addition to the in-line stereo amplifier, there are other models designed to boost the signal strength of radio frequency (RF) signals, digital broadcasts such as those on cable TV, or even telephone calls. Basically, whenever a weak audio or optical signal exists, an in-line amplifier can usually increase the signal strength satisfactorily.

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Discussion Comments


@Melonlity -- They make these for indoor antennas, too. In fact, a lot of those companies that brag about having a device that will let you drop cable and pick up a bunch of stations for free are usually selling little more than an amplified indoor antenna.

One thing that is very novel about antenna amplifiers these days is that they are needed because an HDTV signal is either off or on. Back in the analog days, you would just get a little snow on your TV screen if a television station wasn't coming in strong. Now a weak signal produces no picture at all, so an in-line amp is often needed to boost it enough to be viewable.


One of the more common in-line amps is used in conjunction with an external television antenna. If you live near a city with television stations but not close enough to pick up all stations clearly, an amplifier may be just the thing you need. Those are often included with roof antennas, in fact, because they are usually a needed accessory.

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