I read that Line output impedance is about 100 ohm and input about 10k ohm. However I cannot find information about XLR connection (output) impedance (in a preamp, for example). XLR input in mic preamp is usually around 1.5-2k I believe.

I wonder what's the output impedance when I take signal from XLR output of my mic preamp, for example.

Also, will impedance on Line output differ from impedance on XLR output (with the same microphone and settings used, of course)?

  • XLR cables carry Line-Level signal all the time. Most of the time an XLR output is a line output; unless it’s a microphone output or a DI box. Generally a device is defined as either low impedance(Z) 600ohms or less, and high impedance. Commented Jul 17, 2019 at 10:16

1 Answer 1


The confusion comes from the fact that “line level” is a sort of signal standard and “XLR” a type of connector or cable that uses such connectors. So there is no “XLR” type of signal.

XLR cables can carry mic level or line level analog audio, digital audio (AES/EBU), and in rare cases, MIDI, lighting control signals, or other types of signal. So there is no one “XLR” signal standard.

Furthermore, it’s most precise to talk of devices having input and output impedances, not signals or cables. For example, a Shure SM-57 microphone that might be plugged into an XLR cable has a nominal output impedance of 150 Ohms and an actual output impedance of about 31 Ohms. You could plug the other end of that XLR cable into an A&H GL2400 mixer mic input which seems to have a nominal input impedance of 2k Ohms. But other microphones and other consoles will have different input and output impedances even though they are all sending and receiving mic level balanced signals on XLR cables.

To find the output impedance of your mic preamp, you’ll want to look at the documentation.


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