line in?line out?

[only_lonely]

I am doing testing job currently.
While i looking at specs, quite confuse witht he word"line in" and "line out" port.
May somebody here briefly explain to me.
Thanks a lots!

 

[audioguru2]

For audio signals, line level is between about 100mV to 300mV RMS. Microphone level is 2mV to 20mV and speaker level is a few volts to many volts.
Components like a tuner, CD player or other sound signal circuit use line level to feed an amplifier.
"Line in" is the line level input to an amplifier. "Line out" is the line level output of a component.

 

[only_lonely]

So, if i connect an external speaker at unit A, that port which I plug is "line out" port.

Then the "line in" port is when i play music at my PC,then i use audio cable to connect my pc to the unit A, to play the sound at that unit A.

Am I correct?

 

[audioguru2]

So, if i connect an external speaker at unit A, that port which I plug is "line out" port.

A speaker is supposed to be connected to the output of an audio power amplifier, not a line level output. The line level output can connect to the input of an audio power amplifier.

Then the "line in" port is when i play music at my PC,then i use audio cable to connect my pc to the unit A, to play the sound at that unit A.

Connect the line level output of something to the line level input that you have.

 

[only_lonely]

sorry, i am quite confuse now.
OK.
Now i have a UNIT A which has 2 port, one line in port, one line out port (audio jack). Unit A has an internal left and right speaker.

1) If i have an external speaker to test the unit audio functionality,
which port should i connect it?

2) If i have an audio cable now, and i want to play my PC music on the UNIT A's internal speaker,
which port should i connect it?

 

[audioguru2]

sorry, i am quite confuse now.
OK.
Now i have a UNIT A which has 2 port, one line in port, one line out port (audio jack). Unit A has an internal left and right speaker.

1) If i have an external speaker to test the unit audio functionality,
which port should i connect it?

Nothing. It doesn't have an output for an external speaker. Connect the line out to the input of an audio amplifier and connect the speaker to the amplifier's output.

2) If i have an audio cable now, and i want to play my PC music on the UNIT A's internal speaker,
which port should i connect it?

Its line input of course.

 

[MP1]

Only_,
LINE IN is where your device is accepting or acquiring the audio signal from another source or device. LINE OUT is where your device is sending it's signal to another device.
Hope that clears it up for you.

MP