Recent software update seems to have changed requirement for microphones

[yusufg110]

Hi, I have a late 2006 iMac (2.16 Core 2 Duo/2GB RAM). At present, I
am on 10.4.10 with all updates applied. I am a heavy user of Skype
and use a regular headset (ones with green and red jacks). It used to
work perfectly and I have done multi-hour conf-calls via Skypes and
everybody would hear me perfectly via the headset

A few weeks ago, I observed that I wasn't getting any audio input on
my line-in and replacing headsets wouldn't work either.

The same headsets however worked perfectly on PC's or if I use a
HarmonyExpress USB Audio stick

http://www.miglia.com/harmonyexpress/index.html

I recently tried testing other late 2006 iMac's with various headsets
and it showed the same behaviour as observed via this test

Go to System Preferences->Sound->Input

Speak into the headset and you don't see the level indicator move at
all. Switch to Built-In Microphone and you'll see the level indicator move

I called in AppleCare and my Logic board was replaced but the problem
still persists

Did a recent software update change the sensitivity of the line-in
jack to require Line Level signal instead of working with Microphone
level

Regards, Yusuf

[ZhaoYun]

I am also having the same problem with Logitech Notebook Premium Headset. Using it on my XP Machine works fine, but when I plug in to the Audio Line In of my iMac 24" 2.4ghz, it does not work at all.

However, if you refer to the user manual in Apple website, it says the port is for self-powered microphone..mine obviously is not. So, I do not know if this is a problem.

Anyone have similar experience ?

Thanks.