Line Stage vs. Preamp: What’s the Difference?

When it comes to audio recording, there are various terms that you should know. Sometimes, however, things can get confusing, and you may end up misusing some of the words in conversations. An example of this is the preamp and line stage.

The difference between a line stage and preamp is the type of signal amplified. A preamp can amplify weak signals to make them loud enough for a recording, whereas a line stage is a type of preamp that can handle stronger signals, though it doesn’t process phonograph signals or have tone controls.

While some people tend to use these terms interchangeably, owing to the fact that they both amplify audio signals, there are distinct differences between these two. Read on and discover these differences and which one you should use depending on what you’re trying to do.

Preamp

The Differences Between a Line Stage and a Preamp 

A lot of the confusion between the line stage and preamp lies in the fact that a line stage is a kind of preamp, and these two share a lot of the same characteristics. Because of the similarities in function, many people often mistake a line stage with a preamp. But these two have their differences.

What Is a Line Stage?

The line stage is where you can connect various sources such as a tape deck, a CD player, a tuner, or a DVD player, among many others.

A line stage typically will not include a phono section. In the old days, all preamps had tone controls and a phono section. Then manufacturers dropped the tone controls before the phono section was rendered obsolete with the rising popularity of CDs and the dying out of vinyl records.

One important characteristic to note is that a line stage preamp will always provide gain.

What Is a Preamp?

A preamplifier will help you get a louder sound. These devices increase gain so that they can boost a weak signal to a line-level signal. 

Preamps allow you to:

  • Get less distortion for your music
  • More audible sound for your classic instruments
  • Better dynamic range
  • Bring a weak signal to line level

For instance, the moving coil in microphones will not produce a strong signal capable of running through your processing gear or digital audio workstation, so you will need a microphone preamp to make it louder and usable. A microphone preamp will raise the weak signals coming from a microphone, boosting the voltage and volume of these signals so you can work with them.

In contrast to a line stage, there are types of preamps that will only pass a signal but will not amplify your audio. For instance, passive preamps will pass a signal but will not process it.

Do You Need a Preamp?

Most people think that a preamp is a magic solution that can improve their recordings. This notion is simply not true. If the audio is horrible, then there is nothing that a preamp can do. It will only make the bad sound louder.

It’s also possible to overdo things when using one. A preamp can result in the signal being big enough, so to keep your recordings from sounding bad, avoid clipping the signal. Instead, try to keep the amplification at or just below the threshold without going over. Doing so will result in clean and precise signals that are just above the noise floor. 

With that in mind, you should know that before you buy a preamp, you should first see if the problem is with other devices in the signal flow path. If you are already using a top-notch microphone or have invested in some of the best speakers, and the sound quality still is not good, then you might want to consider investing in a preamp.

This video will tell you more about what a preamp is:

Types of Preamps

There are several types of preamps according to what they do or how they are powered. Active preamps have the circuits that draw power to provide gain for your signals. These can use gain devices such as op-amps, transistors, and tubes. These devices are what’s missing with passive preamps. As such, using a passive preamp will mean that you cannot amplify the signals that pass through it.

Preamps can also be classified according to what type of compensation or amplification they provide. For instance, a line-level preamp doesn’t include microphone or phonograph input. 

A microphone preamp strengthens a microphone signal. From the weak vibrations of the small condensers inside the microphone, this type of preamp brings this signal to line level. It is how we can hear a singer singing a song or an instrument getting picked up by the microphone.

A phono preamp, on the other hand, amplifies the weak analog signals coming from your phonograph. A vinyl record often has a very weak signal output, and the phono preamp will boost the volume to line level, making it sound as loud as music coming from CDs or tapes.

A phono preamp also comes with an RIAA equalizer that corrects the RIAA curve. LPs and vinyl records are often processed so that the higher frequencies are amplified so that surface noise is minimized. The bass frequencies are also cut.

The phono preamp boosts the low frequencies while also emphasizing the higher frequencies to reproduce the recorded analog sound.

Criticisms About Preamps You Should Know

The thing with preamps is they will introduce noise into your signals at every gain stage you have. What’s more, as you can see, you don’t always need a preamp.

Some of your equipment, such as an audio interface or a digital to analog converter, might already have a preamp built into the device.

Should You Use a Line Stage or Preamp?

You should avoid sending a line-level signal to a preamplifier meant for weaker signals such as a mic preamp. Mic and instrument level audio are often very weak, so they need a preamp to raise their signal levels to line level.

Putting a line-level audio source in a mic preamp, for example, will make it too loud, and the sound becomes distorted.

Using a line stage should be done when you have higher level signals before it goes through amplification, while different types of preamps can take care of the sound coming from a microphone, a phonograph, or your instruments.

That is to say, if your setup includes a phonograph, then you should have a preamp rather than just a line stage. But if you only have line-level inputs, such as DVD and CD players, tape decks, and tuners, then a line stage is sufficient.

But what if you have invested in an excellent line stage then suddenly realize it would be a great idea to listen to LP records? Does this mean you have to sell or dispose of your line stage and get a preamplifier with tone control and phono preamp? Not really. You have to add a phono preamp to your signal path, and then you can still use your current line stage. 

Conclusion

The difference between a line stage and a preamp is that a line stage is just another type of preamp, typically one that can handle line-level sound strength. It does not process phonograph signals, and for that reason, you will still need a preamp to handle the weaker signals, such as those coming from microphones, vinyl records, or your instruments.