D
dolecekq
New member
What does a preamp do? Does it just make the signal stronger or does it improve the quality of the mic sound?
PRHunt
I void warranties
A preamp will boost a signal from a microphone or instrument by amplifying the signal voltage and current.
Some preamps are designed to be as sonically transparent as possible. These will not noticeably alter the microphone sound, and are a good choice when you want to make natural sounding recordings of acoustic sources.
Other preamps will alter or "colour" the sound. This happens because of sonically pleasing harmonic distortion of the signal, which results from the particular circuitry. Descriptors like "fat", "warm", "aggressive", "smooth" are often used.
The choice comes down to what sort of sound you want to achieve.
Paul
Some preamps are designed to be as sonically transparent as possible. These will not noticeably alter the microphone sound, and are a good choice when you want to make natural sounding recordings of acoustic sources.
Other preamps will alter or "colour" the sound. This happens because of sonically pleasing harmonic distortion of the signal, which results from the particular circuitry. Descriptors like "fat", "warm", "aggressive", "smooth" are often used.
The choice comes down to what sort of sound you want to achieve.
Paul
Bobbsy
Boring Old Git
A bit more detail to continue on from PRHunt's excellent reply.
In audio parlance, there are 2 main "levels" of signal.
Microphone level is extremely low--measured in thousandths of a volt. This is because the mic either generates the electricity (or modifies it in the case of condensers) with the tiny movements in the air from the sound waves. You can imagine how small the movements of the mic diaphragms are, hence the small amount of electricity involved. One of the drawbacks of the mic level signal is that, as it's so low, it's also quite vulnerable to outside electrical interference--an arcing thermostat can introduce clicks or running alongside a mains extension cable can introduce hum. Using balanced circuits helps a lot (hence all decent mics being balanced XLRs rather than an unbalanced signal) but it's always good to bring the mic signal up to line level as soon as possible--which brings me neatly to...
Line level, on the other hand, is an arbitrary standard used inside mains powered gear or for exchanging audio among mains powered gear. You can read up on the various standards for line level in the Wikipedia article but, in essence, standard line level is +/- 1 volt, i.e. much higher level than mic level.
The purpose of a mic pre amp is to raise the level of the very low mic signal up to line level to make it useful in other pieces of gear. The pre amp has to do this without adding extra noise or distortion to the signal. As PRHunt says, one school of thought is to keep the pre amp as neutral as possible. However, others deliberately add certain colourations (often that elusive thing, "warmth") to the signal.
One thing worth saying is that very often pre amps are hidden in other bits of equipment. If you have an audio interface, any mic inputs will go through a pre amp before the analogue to digital conversion. Even the rubbish mic inputs on a lap top have a pre amp inside, although a pretty poor quality one.
In audio parlance, there are 2 main "levels" of signal.
Microphone level is extremely low--measured in thousandths of a volt. This is because the mic either generates the electricity (or modifies it in the case of condensers) with the tiny movements in the air from the sound waves. You can imagine how small the movements of the mic diaphragms are, hence the small amount of electricity involved. One of the drawbacks of the mic level signal is that, as it's so low, it's also quite vulnerable to outside electrical interference--an arcing thermostat can introduce clicks or running alongside a mains extension cable can introduce hum. Using balanced circuits helps a lot (hence all decent mics being balanced XLRs rather than an unbalanced signal) but it's always good to bring the mic signal up to line level as soon as possible--which brings me neatly to...
Line level, on the other hand, is an arbitrary standard used inside mains powered gear or for exchanging audio among mains powered gear. You can read up on the various standards for line level in the Wikipedia article but, in essence, standard line level is +/- 1 volt, i.e. much higher level than mic level.
The purpose of a mic pre amp is to raise the level of the very low mic signal up to line level to make it useful in other pieces of gear. The pre amp has to do this without adding extra noise or distortion to the signal. As PRHunt says, one school of thought is to keep the pre amp as neutral as possible. However, others deliberately add certain colourations (often that elusive thing, "warmth") to the signal.
One thing worth saying is that very often pre amps are hidden in other bits of equipment. If you have an audio interface, any mic inputs will go through a pre amp before the analogue to digital conversion. Even the rubbish mic inputs on a lap top have a pre amp inside, although a pretty poor quality one.