XLR Mic or XLR Line?

[Don Kinsley]

What is the difference between setting up an oncamera XLR shotgun to XLR mic or XLR line? I don't understand the difference? Can anyone explain? Thanks.

[Chris Hurd]

Moved from Canon XH to All Things Audio.

Who wants to explain the importance of matching impedance? Thanks in advance,

[Battle Vaughan]

XLR mic level is for microphone level inputs -- somewhere between -50 and -30 db, iirc. Line level is the much higher voltage from outputs from mixers, things like that, at +4 db.

If you hook up a mic at line level, there is not enough amplification to the signal and you won't hear anything much if at all. If you hook up a line level signal on the mic setting you will severely overload the preamps in the camera and get really ugly distortion.

Incidentally, since the camera audio controls show the output from the camera preamps, you can make that overloaded output a quiet as you like and it will still be the same overloaded and distorted waveform, just with less amplitude...by way of saying, you can't adjust for the difference with the volume controls, which many people seem to believe...you need the appropriate signal level coming into your preamps, and that is what the mic/line control is for...../Battle Vaughan /miamiherald.com video team

[Les Wilson]

Searching on "Mic Level" and "Line Level" should turn up lots of information. In a nutshell, without using engineering terms, Mic level is for mics. Line level is for audio sources that have been amplified (e.g. When mics that go through a mixer, the output of the mixer is usually line level). Don't confuse phantom power or batteries in Mics as making them amplified ergo line level. Most mics require power and produce mic level.

Your on-camera shotgun is mic level and needs power either from an internal battery or from the camcorder's 48v phantom power for the XLR channel you plug it into. Most camcorders have independent phantom power nut some camcorders only have a single line/mic switch for both channels.

[Don Kinsley]

Thanks for the replies -

[Don Palomaki]

One added note, in general line level inputs have a lower noise floor (background hiss) because they are amplified less than mic inputs. This is good if your source provides a high enough clean signal.

Line level audio signal peaks at on the order of 0.3 to 3 volts
A MIC level signal peaks about 100 time less, or on the order of 3 -30 mV.

Line level comes in two common flavors: consumer line level which is about -10 dBV (nominally around 0.3 volts to drive 10K ohm load, and professional line level which is more like +4 dBV (around 1.5 volts) to drive a 600 ohm load. Consumer line level often comes from RCA jacks, while professional line from XLR or 1/4" 3-conductor phone jacks, but this is not assured.

Some mixers offer options for MIC level output as well as line level output, and some have a tape output as well, which often is consumer line level.

The output of different microphones for a given sound input varies widely

It nets to you need to read the specifications for the gear at hand, and above all run some tests before for any important or money shoot.