Computer audio

[jb]

iMac Intel i3 21.5" OS 10.6.8

Attachments "1- audio line in" and "2- audio line out" show my System Sound Preferences panels.

1- audio line in
[attachment=2568:1__audio_line_in1.jpg]

2- audio out
[attachment=2567:2__audio_out.jpg]

3- I connected an analog sound source to my External Speakers Amplifier's mini input, the sound is OK.

4- When I connect the same sound source to the Computer's Mic/Line mini input connector, there is no sound
coming from the computer's internal speakers, though the Input level "meter" indicates that the input is "alive".  

5- The internal speakers are OK as I can play an audio file on my desktop through them.

6- When I change the sound input from "Line in" to "Internal microphone", the same thing happens, i.e. my voice
registers OK on lhe level "meter" but not in the internal speakers.

7- Am I correct to assume that my computer has a defective Mic/Line input circuit "after the input level circuit"?
8- Or is there another preference or setting somewhere that I should set?
9- Or does the Mic/Line connector not accept an analog audio source? (which would not make sense)

jb

[Xairbusdriver]

I was just reading about an audio problem at another site and wondered if you've tried this:

Start up the Mac in Safe Mode. Hold down the shift key during the Restart to get into that mode. If this corrects the problem it probably means some third-party software is the problem. And, that software is probably being started up during a normal Startup.

[jb]

Found this is a normal behavior by design. Don't know why.
But found a workaround, an app called "Linein" which allows one to select the input to "Pass Thru" or not.
The app can be found here.

Thanks Xabd. But starting in Safe Mode did not help. Moreover the System Preferences Sound panel showed there were NO Input nor Output devices found.

jb

[Xairbusdriver]

My bad, I didn't realize it was an app that was giving you trouble. I have an audio app (Sound Studio) that allows the same thing. I think the reasoning is to prevent a feedback loop if you were using the built-in or any connected mic. I think it's best to always use headphones when recording, anyway. That way you should be hearing what is going into the computer.