A preamp (preamplifier) is an amplifier that has two main functions. Firstly, it amplifies a low level signal to a ‘line level signal’; this essentially means that a weak electronic signal is converted into an output that is strong enough to be processed or amplified further. The second function is to provide a cleaner output with less noise and unwanted distortion. Without using a preamp the sound can become unpleasantly distorted. In this post, we explain how it all works, and why preamps are fundamental to a professional recording.
What is the purpose of a preamp?
An audio signal level refers to the output voltage of a given instrument or piece of equipment. There are four different audio signal levels (in ascending order): Mic, Instrument, Line, and Speaker. Most professional recording equipment, including compressors and analog/digital converts, require a line-level signal in order to process sound. The purpose of a preamp is to boost weaker Mic and Instrument signals to a line-level, allowing them to be accurately recorded, mixed, and mastered.
Why use a preamp?
A preamp improves the quality of a recording. This is especially true of external preamps, which retain transparency even at high gains (for example, above 50/60 dB). They can even be used to give your sound a certain style; a slightly ‘messy’ 60s tube vibe, for instance, can only be achieved in the studio with the help of an external preamp. If you use one of the more advanced preamps, you’ll also find other features such as phase reverse, low cut, and pad switches.
Different type of preamp
Tube based preamps use vacuum tubes to amplify a signal. In contrast to other types of preamp, they help to create a warmer, richer sound with subtle distortions. These distortions actually create ‘even harmonics’, which are tones that consist of the same note but in higher octaves. Tube preamps also tend to be popular for the simple reason that they look interesting and the glowing of the tubes can give any studio a vintage aesthetic.
Solid state preamp
Solid state preamps, as the name suggests, use solid state electronics to amplify their input signals. They differ from tube preamps in that they tend to create more ‘odd harmonics’, which can add dissonance to the overall sound. Having said this, solid state preamps can handle higher levels of gain, which makes them an ideal choice for anyone looking to keep the sound of the output as close as possible to the input. Overall, they provide a clean, transparent tone.
Hybrid preamps are a combination of tube and solid state preamps. They’re usually designed as a solid state preamp with an extra tube for added warmth and colour. The benefit of this setup is that they’re able to manage high levels of gain whilst retaining a degree of control over distortions. This flexibility makes hybrid preamps a good option for home producers, but less suitable for a professional studio; this is because they generally can’t achieve the same strong, clear sound of a solid state, or the same warmth as a tube preamp.
How to choose the right preamp
The right preamp can improve the overall quality of an output, making the sound more polished or fitting with the tone of the track. With a few different types of preamps available, it’s important to choose the right one for your needs. If you want to record a guitar with a clean cut tone, for instance, then a solid state preamp is the one for you. If you’re looking to concentrate on vocals, on the other hand, a tube preamp might be the better choice, as it will allow you to add more character and warmth into the sound.
If you’re looking to produce a professional recording of your music, get in touch with Kore Studios. Our award-winning recording studios are based in South-West London, and have hosted artists such as Amy Winehouse, Ellie Goudling, and Kasabian, to name just a few. With years of experience and an expansive range of recording equipment available, our producers will work with you to define and record your sound.