What is a preamp?

High-end stereo system with turntable, preamplifier, power amplifier, phono amplifier and CD player.
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Preamps are found in all types of audio setups, from headphones to home theaters. But what are they and what can they do for you? These devices are quite simple, but they are used in a complex way.

What does a preamp do?

As the name suggests, the preamp or preamp sits before an amplifier in your audio signal chain. In most setups, the preamp is the very first stop on the way to your speakers after leaving your playback device.

For example, in a hi-fi setup with a digital audio player, the signal leaves the player and goes into the preamplifier. After the preamp, the signal travels out and into a power amplifier, which then sends the audio to your speakers.

But what does the preamp do in this scenario? The most important function of a preamp is to raise the level enough for the power amp to work with. Power amplifiers generally act as signal multipliers, so increasing the level of the preamp increases the volume significantly.

Boosting the signal level is often not a preamp’s only job, although it is the fundamental function they were designed for. The idea is simple, but you can find everything from very affordable utility grade preamps to far more expensive audiophile grade preamps.

One important thing to note is that we are talking about preamps for home use. You’ll also find mic and line preamps used for recording instruments and vocals. These work similarly but amplify the signal so it’s easier to pick up.

Common Preamp Features

While preamps are defined by boosting the signal level, they often have other built-in functions. In audiophile and home theater circles, however, the lack of additional features can sometimes be a feature in itself.

One of the most common features you will see in preamps is equalization (EQ). This is typically a Baxandall-style two knob EQ with bass and treble controls, but you’ll see others. These can range from a three-band EQ with bass, middle, and treble controls to a multi-band graphic EQ.

Another common feature of preamps is signal routing. In most cases you can use it to operate several playback devices such as Blu-ray players and record players in one amplifier.

This is being extended to more modern devices as well. A preamp like the Yamaha MusicCast Wireless Streaming Preamplifier WXC-50 adds Bluetooth, AirPlay and Spotify support to an A/V receiver or HiFi stereo system. In this case, Yamaha’s MusicCast multi-room audio system is also supported.

Wireless streaming preamp

When do you need a preamp?

You may have noticed that the features above sound like features you’ve seen in other products but not preamps. That’s because most of us don’t use standalone preamps, but rather preamps built into other products.

For example, if you’re setting up a home theater system, you don’t need to think about a preamp, as one is already built into your A/V receiver or soundbar. Similarly, with a home stereo, you interact with the preamp, but it’s built into a larger device.

Those who take their audio quality seriously aren’t always satisfied with the all-in-one setup that an A/V receiver or integrated amplifier offers. Audiophiles in particular often use a separate preamp, equalizer and power amplifier, giving them complete control over every aspect of the signal chain.

Audio Technica

There’s another area where you often need a preamp: turntables. Many A/V receivers don’t have a separate input for turntables, which have a much lower output power than other devices. Unless your turntable has its own built-in preamp, you will need a separate phono preamp such as the Pyle Phono Turntable Preamp, which is placed between the turntable and your receiver or amplifier.

Phono preamplifier for turntables

Pyle Turntable Preamp

If you’re a vinyl lover with an A/V receiver or amp that lacks a preamp, don’t let that get in the way. This preamp brings your records to the correct listening volume.

How to choose the right preamp

As we’ve discovered, preamps are typically built into A/V receivers, integrated amplifiers, and other products like soundbars these days. For this reason, knowing if you even need a standalone preamp is most important.

If you need a preamp, make sure you know what you need. It’s easy to get bogged down with additional features, but remember that you can always add more features to your signal chain later if you’re using a standalone preamp.

Finally, make sure you know the other gear you have. Preamps typically use simple connections, but make sure you understand the basics of audio connections before you start shopping.

TIED TOGETHER: Home Theater Wiring: What Are All Those Connections?

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