what does a pre amp do

What Does a Preamp Do and Do You Need One?

Producing high quality audio is both an art and a science. One of the questions we get asked the most is, “What does a preamp do?” You may be wondering what all the hype is and if you really need  one.

A preamp or preamplifier can play an important role in your audio setup. We’ll explore this in depth and also help you differentiate between a preamp and an amplifier.

What Does a Preamp Do?

A preamp is the audio device that connects to the musical instrument or mic and takes this signal to a line-level signal. Thereafter, the preamp connects to the power amp, which in turn connects to the speakers and produces great sound for you.

The purpose of a preamplifier is to take a weak audio signal, increase its gain, and boost it to line-level signal. A gain stage refers to every incident when an amplifier is utilized in the path of a signal. Passing through an additional gain stage increases the signal volume and makes it easier to use for the next device along the line.

If you have a device with low signal strength such as a microphone, you need to increase this signal to line level. Failing to do so, you will get a very terrible sound coming from the speaker. 

Preamp Types

Preamps exist in various forms. There are external preamps and built-in ones. With an external preamp, there is a separate device that handles these functions and is connected to the musical input as well as to the amplifier.

The other side is the built-in preamp. This is incorporated into various devices as a preamplifier circuit. Many audio interfaces and mixers have built-in preamps.

Benefits of a Preamp

Using a preamp has several benefits. This device will improve clarity and increase the dynamic range for your high headroom circuits. 

It is worth noting that while preamps can do a lot for your audio quality, they won’t magically resolve all the sound issues that you have. Preamps help produce great sound, but if your audio is already distorted, they may not be able to do much to help with that.

 There are many benefits of having a dedicated external preamp. These include:

  • Better sound quality especially when dealing with higher gains
  • More gain than can be offered by internal preamps, which go up to about 60 dB
  • Lower noise although any internal preamps also have this feature
  • Additional features and functions such as pad switches
  • Special sound quality

There are many ways that an external preamp can improve your sound quality. If you are still a novice, you might not be ready to make an investment in an external preamp. You can get away with a high quality audio interface with a built-in preamp.

You can also improve your other devices, including high output condenser mics.

what does a pre amp do

What Does a Power Amplifier Do?

When talking about a preamp, we would be wrong if we didn’t mention the power amplifier and the differences between the two. 

There are different types of amplifiers. Some have the preamp and power amp combined in one device, while in others, these exist as separate units.

The line-level signal from the preamp is passed on to the power amp, which connects to the speakers. The purpose of the power amp, when the two devices are separate, is to deliver audio signal to the speakers for volume amplification.

Do You Need a Preamp?

Consider this, a microphone has a low signal that must be boosted with significant gain before it can be transmitted to a speaker. You are looking at about 30-60 dB.

The signal coming from a guitar or bass does not need nearly as much amplification as that coming from a microphone, so you would be looking at around 20-30 dB.

Most sound sources do require some level of gain, so you would need a preamp. As mentioned, there are external and built-in preamps available.

If your sound source or audio interface already has a built-in preamplifier, then this is good enough, and there is no need to augment this with another separate preamp. Where devices do not have internal preamps, then you are going to need an external preamp.

There is quite a big debate about whether you need a preamp or not. External preamps come at a cost, so it might seem like an unnecessary investment. Now that we have looked at how the preamp works and the benefits it can offer, it should be clear that in most cases, you’re going to want to have one in your setup.

Tips to Help You Pick a Good Preamp

Navigating your way through the technical specifications of any preamp is likely to leave you feeling a little lost if you are new to musical terms and fields. Much of the language used there is only understood by sound engineers and other technical people.

Whether you are a novice with amps or know a thing or two, there are a few features you should be looking out for. With so many different preamp types available, it’s best that you find one that meets your needs.

One of the questions you should ask about a preamp is around the number of channels that it has. Some preamplifiers have only one channel, while others may have eight or more. You need to pick a device with as many channels as you require for your purposes.

Some of the types of preamps include tube ones, FET ones, and solid-state models. All of these have pros and cons, which you should take into consideration. Your needs are likely to be very different if you are a beginner in the musical space or a professional musician playing in a band.

Closing Thoughts 

Setting up your audio equipment is a critical step that you shouldn’t brush over. You’re going to need high quality devices and the appropriate amplifying equipment.

What does a preamp do? Do you really need one and what is the difference between a preamp and power amp? We have discussed the answers to these questions in depth and shown the importance of benefits of having a preamplifier in your sound instrument setup.

Leave a Comment