Different types of audio signal levels. The basics that musicians need to know
Introduction
How many times have you plugged a jack into an input just because it fits, without checking compatibility? Many things can go wrong, from hearing no sound to complete distortion. Wouldn’t it be easier if you always knew what goes where so you don’t have to spend your limited gig’s setup time on troubleshooting?
In this article, we will go through all four different types of audio signal types that a musician deals with. Understanding the basics of signal types is essential for working musicians. We will explain the specifics of each signal type, what produces them, and how to work with them so that your music gear works and sounds the best gig after gig.
Every signal type has its purpose in the signal chain. This article is an explanation of what each type is and how to work with it.
What is signal level?
The signal’s level or type is determined by the voltage level it produces. It is also called the signal’s strength and tells us how loud a signal is.
The four signal types are (from lowest to highest voltage):
- Microphone level ( 0.001 to 0.01 volts / -60 to -40 dBu )
- Instrument level ( 0.1 to 1 volt / -20 dBu )
- Line level ( 0.45 to 1.7 volts / -10 dBV to +4 dBu )
- Speaker level ( 20 to 50 volts / 70 to 120 dB )
For comparison purposes, the voltage levels that are stated are the most common levels. As we can see:
- Instrument level is about 1000 times stronger than microphone level
- Line level is several times stronger than instrument level
- Speaker level is 20 to 50 times stronger than line level
The voltage level is what also determines how cables are made. The low voltage level in microphone cables is the reason why balanced cables were invented. On the other hand, speaker cables are much thicker because of the highest voltage of signal cables that they carry.
It is all about making signals compatible with various stages in the signal path. If we need to send a microphone-level signal into a line-level input we need a microphone preamplifier to alter the signal to a compatible type for the line-level input. The same analogy can be used to describe what needs to be done so a speaker can reproduce an audio signal. It needs an audio amplifier to boost line level signal into speaker level signal.
Microphone level
This is the weakest type of audio signal, which means that it produces the smallest voltage. Wherever we use a microphone we use balanced cables that use polarity flipping in one of the signal wires inside of them for cancelling noise. Noise is picked up with every signal type, but since a microphone-level signal is very weak, it is a major issue for them.
Microphone cables are plugged into XLR inputs on mixers or audio interfaces. This signal is then boosted via a microphone preamplifier to line-level which is the standard signal-level that outputs from all audio devices that “gather” multiple inputs.
Instrument level
This signal level is the next in strength after the weakest, the mic level. It is produced by guitars, basses, and similar instruments that use pickups. Their signal also needs to be boosted to line-level. This is done by using DI boxes, guitar pedals, processors, or preamps if not using mic’d amps. These devices usually have line-level outputs and their signals are sent to line inputs on mixers.
When we use a microphone placed in front of a guitar cabinet’s speaker the signal is still mic-level and is treated as any other microphone. In this case, the boosting is done in the mixer or audio interface as mentioned before.
Line level
Img mixer output or keyboard
Line-level signals are stronger than instrument-level. They are produced by keyboards, drum machines, and other audio devices such as signal processing effect units, audio interfaces, DI boxes, mixers, and so on. These signals are plugged into line inputs on mixers and do not need boosting inside a mixer.
All signals that reach a mixer are somewhere boosted to line level. Either through external devices such as DI boxes or within the mixer, now we have a group of the same level-type signals that are easy to work with.
Line level signals are the standard type of signal level that audio equipment uses.
One more thing needs to be said. There are two types of line levels:
- Professional line-level
- Consumer line-level
The first is used for professional audio gear, while the second is used for consumer audio devices such as Hi-Fi systems, laptops, and smartphones. Consumer line-level is weaker than professional (5-10 times). This is why it is common to use a DI box for connecting a laptop to a mixer. It not only makes the audio signal levels match but also provides protection for the laptop,
Speaker level
This is the strongest audio signal level. It is what makes speakers vibrate, which produces airwaves that produce the sound that we hear.
Mixers and audio interfaces have line-level outputs. These outputs are stronger than mic and instrument level signals but still not strong enough to physically force speaker cones to vibrate. To achieve a strong-enough signal level for speakers we use amplifiers. They receive line-level signals and transform them into speaker-level signals.
A standard signal flow using separate devices travels from mixer to amplifier to speaker. Speaker cables are used to connect amplifiers with speakers. These cables are thicker than all other cables due to the voltage they carry. These speakers are called passive speakers (no amp inside).
Active speakers do not have speaker inputs because they have integrated amplifiers within the speaker cabinet. The speaker-level cable is located inside the active speaker cabinet, which is why active speakers have line-level inputs. When using active speakers, we are technically plugging into amplifiers, not speakers.
Conclusion
Now that we have covered the four types of audio signals we are better prepared for future gigs where live sound plays the major role. Connecting an audio signal that is stronger than what an input expects is wrong and that the other way around can work. But still, the best thing is to try to match audio signal levels wherever possible.
By better understanding types of audio signals and signal flow, we will be less likely to make mistakes which often lead to confusion and loss of setup time. Being prepared is what makes all the difference when playing gigs frequently. When your band prepares for a gig, what is the most common issue? If you are spending too much time on your setup leave a comment below and I will try to give you the best answer for your band.
