Mic Line and Instrument Level – What’s the Difference?
Mic Line and Instrument Level – What’s the Difference? – Ever looked at the back of your audio interface and wondered what the difference is between the mic, line, and instrument inputs? You’re not alone. These terms refer to the strength of an audio signal, and understanding them is crucial for getting good quality recordings.
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Delving into Decibels (dB)
Audio signals are measured in volts, but a unit called decibel (dB) is more commonly used. It expresses the relative strength of a signal compared to a reference level. Here’s a breakdown of the three main levels you’ll encounter:
- Mic Level: The weakest signal, typically produced by microphones. It’s in the millivolt (thousandth of a volt) range and needs a boost before it can be used effectively. Mic inputs on your audio interface provide this boost, thanks to a built-in preamplifier.
- Line Level: A much stronger signal, around one volt. This is the standard level for signals that have already been pre-amplified, like those coming from keyboards, CD players, or mixers.
- Instrument Level: Somewhere between mic and line level. Electric guitar pickups, for example, output instrument-level signals. They’re stronger than mics but not as strong as line level and often require a preamp to reach their full potential.
Connectors and Impedance
Mic level signals typically use XLR cables, known for their balanced connection that reduces noise. Line level and instrument level signals often use TRS (Tip-Ring-Sleeve) cables for balanced connections or TS (Tip-Sleeve) cables for unbalanced connections.
Another factor to consider is impedance, which refers to the resistance a signal encounters when traveling through a cable. Mic level signals have high impedance, while line level signals have low impedance. Instrument level can vary but generally falls somewhere in between. Matching the impedance of your instrument or microphone to the input of your audio interface helps ensure a clean, undistorted signal.
Why it Matters
Plugging a microphone directly into a line input might result in a very quiet recording, as the input isn’t designed to handle such a weak signal. Conversely, plugging a hot line-level signal into a mic input could overload the preamp and cause distortion.
Making the Right Connections
Most audio interfaces will clearly label their mic, line, and instrument inputs. If you’re unsure, consult the user manual. Here’s a quick guide:
- Use mic inputs for microphones.
- Use line inputs for keyboards, CD players, mixers (basically anything that outputs a pre-amplified signal).
- Use instrument inputs for electric guitars, basses, and other instruments with pickups (unless they have a built-in line-level output).
By understanding mic, line, and instrument levels, you can avoid signal mismatch issues and ensure you’re capturing the best possible audio quality from your equipment. Now you can rock that recording session with confidence!
This looks great Simon
best Carl
Clears a lot, thanks for the hole information!
glad you found it useful. If you have any specific questions feel free to ask.
Thanks for the info on DI boxes. Would I be right in presuming the output from the box would be connected to a mic level XLR input on a mixing desk or audio interface?
That’s correct. to restore the reduction in output signal level the DI box needs to be be plugged into the console or audio interface mic input.
So what's the difference of a Preamp and a DI box? They both convert to line-level signal.
Sir, can i use the mic level input to play an ipod or laptop music or do i need to connect them to the line level. which do you prefer using?
Hi Francis, thanks for the question. You should wherever possible plug your ipod or laptop into the line level input to ensure optimum signal strength and best signal to noise ratio.
Hi Man,
Thanks for the explanation, but while it seems well written, it has brought me no closer to understanding what I am supposed to do with my various sound sources and inputs. The reason for my confusion is the following:
When discussing Mic level, you mention millivolts. and dbm. When we get to line level, its dBV and dBU (and dBm? is that interchangable with dBU?). When I look at the spces for example of my SM58, Impedance is in Ohms (Omega symbol), not dBm, and sensitivity is in dBV/Pa and mV. In short, the unit of measurement is both confusing and ever changing and so I dont know what exatcly it is I am reading. So, while I can repeat back what I read, Im not understanding it. I was hoping to understand without having to master the electrician-type jargon, but it seems thats not gonna happen. Ive always had a hard time understanding electricity. I guess I'll go try wikipedia again for the terms and hope it starts making sense one day.
-Alex-