However, if you record very quiet sources (grass growing, whispers, paint drying, etc), or you’re using ribbon mics, you might still benefit from an external preamp doing this hard work.īeware : Specifications can be deceiving.
More gain: The built-in preamps inside your interface usually offer less than 60dB of gain.Note: Voltage Gain in dB = 20log(output voltage/input voltage) That is why mic preamps can impart so much color to the sound, and also why the noise floor is such an important consideration with preamp design. So we see that microphone signals are quiet, delicate signals and mic preamps do a lot of work to increase their level up to line level. Think about that-60dB of gain increases the signal level by a factor of 1000! That increase requires 30 to 50dB of gain. A microphone preamp boosts that signal up to line level, which is about 1.2 volts. Passive instruments, with unbalanced outputs, may require a dedicated direct box, or your interface may provide an input suitable for them.Ī microphone typically produces a signal that is between.
Passive instruments, such as guitars and basses require much less gain, but still around 20-30dB, while synths and drum machines may also need to go through a preamp, though their output level is even higher than mics or passive instruments. See sidebar for some technical info about preamp gain. Usually, you’re looking at anywhere between 30-60dB of gain increase some microphone types, such as ribbon mics, require even more gain. Generally, microphone signal levels are very quiet, so they need a lot of gain to be brought up to line level.
The purpose of a preamp is to amplify low-level signals to what is referred to as “ line level.” Line level is the professional level standard and represents an RMS voltage of about 1.23 volts.
Additionally, you’ll learn how to choose the ideal preamp, what a preamp does, the limitations of the preamps on your audio interface, and the pros and cons of plugin emulations of preamps. In this article, you’ll learn why an external preamp could be a good investment for your particular situation. Many popular audio interfaces contain at least one mic preamp, and many companies claim that these built-in preamps are all you need for perfect audio. You’ve heard they make your signal sound warm, thick, fuzzy, crispy, airy… You own an ok mic, but what you really need is an awesome preamp, right? Wrong. You’ve heard about famous preamps such as the Neve 1073, API 312, or the REDD.47.