What Is a Preamp?

High-end stereo system with a turntable, preamplifier, power amplifier, phonoamplifier, and CD player.
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Preamps appear in all kinds of audio setups, from headphones to home theaters. But what are they, and what can they do for you. These devices are fairly simple, but they’re used in some complex ways.

What Does a Preamp Do?

Like the name implies, the preamp or preamplifier sits before an amplifier in your audio signal chain. In most setups, the preamp is the very first stop on the road to your speakers after coming out of your playback device.

For example, in a hi-fi setup with a digital audio player, the signal leaves the player and runs into the preamp. After the preamp, the signal runs 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 loud enough for the power amplifier to work with it. Power amplifiers generally act as signal multipliers, thus raising the level of the preamp significantly raises volume.

Raising the level of a signal often isn’t the only thing a preamp does, though it is the basic function they are designed for. The idea is simple, but you’ll find everything from very affordable preamps for utility purposes up to far more costly audiophile preamps.

One important thing to note is that we’re talking about preamps for home use. You’ll also find microphone and line preamplifiers, which are used for recording instruments and voices. These work similarly but boost the signal so it’s easier to record.

Common Preamp Features

While preamps are defined by raising the level of a signal, they often have other features built-in. That said, in audiophile and home theater circles, sometimes the lack of extra features can be a feature in itself.

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

Another common feature in preamps is signal routing. Most often, this lets you run multiple playback devices like Blu-ray players and vinyl record players into one amp.

This is also expanding to include more modern devices. A preamp like the Yamaha WXC-50 MusicCast Wireless Streaming Preamplifier adds Bluetooth, AirPlay, and Spotify support to an A / V receiver or hi-fi stereo. 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 mentioned above sound like features you’ve seen in other products, but not in preamps. That’s because most of us do not use standalone preamps, but rather preamps built into other products.

If you’re setting up a home theater system, for example, you do not need to think about a preamp because there is already one built into your A / V receiver or soundbar. Similarly, with a home stereo, you’re interacting with the preamp, but it’s built into a larger device.

Those who take their audio seriously aren’t always satisfied with the all-in-one setup an A / V receiver or integrated amplifier provides. Audiophiles especially will often use a separate preamp, equalizer, and power amplifier, so they have total control over every aspect of the signal chain.

Audio-Technica

There is one other area where you’ll frequently need a preamp: turntables. Many A / V receivers do not have a separate input for record players, which have a much lower output power than other devices. Unless your turntable has its own built-in preamp, you’ll need a separate phono preamplifier like the Pyle Phono Turntable Preamp to place between the turntable and your receiver or amp.

Phono Preamp for Turntables

Pyle Phono Turntable Preamp

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

How to Choose the Right Preamp

As we’ve established, preamps are typically built into A / V receivers, integrated amplifiers, and other products like soundbars these days. For that reason, the most important thing to know is whether you actually need a standalone preamp at all.

If you do need a preamp, make sure you know what you need. It’s easy to get caught up in extra features, but remember that if you’re using a standalone preamp, you can always add other features to your signal chain later on.

Finally, make sure you know the other equipment you have. Preamps usually use simple connections, but make sure you’re familiar with the basics of audio connections before you start shopping.

RELATED: Home Theater Wiring: What Are All Those Connections?

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