Problems with an External Mic

[X-Legs]

I have a Macbook Pro 4,1. The screen broke, so I attached an external monitor, keyboard, and mouse. Everything works great, until I want to do some Skype. I got an external webcam working, but the microphone is posing a real problem.

The internal microphone of the Macbook works fine, but since the laptop is always closed, this is not a practical solution, especially since there is always a humming noise.

I have an external mic that plugs into the Macbook. The mic seems to work. It is labeled "Line-In" with the hardware settings at "Analog Stereo Duplex." When I test it in Audacity, my voice is VERY distorted and low in volume. I tested this mic on a windows machine and it works perfectly. I am running Ubuntu 10.04.

What is the problem? If you need any logs or something, just ask.
Thanks!

[Rumpty]

I would expect the volume off your mic would be low if you are using Line In, unless it is an amplified mic. Is there no external Mic In socket?

[X-Legs]

The external mic is what I have a problem with. I plugged it into what the manual calls the "Audio line in/optical digital audio in" port, turned all the sliders up, spoke directly into the mic, and it sounds low and distorted. Yet, on a Windows machine, it work perfectly.

[lidex]

Use gnome-alsamixer and look for a mic boost option.
Gnome-alsamixer
Using Alt+F2 run dialog

 gnome-alsamixer

Use 'Edit -> Sound Card Properties' menu to enable elements.
Soundcard tab to select / adjust levels.

Installation:

sudo apt-get install gnome-alsamixer

[X-Legs]

Already maxed everything out in the Alsamixer. It's strange, since the internal mic picks up my voice better than the external one, except the internal one pics up all the computer (fans etc) noise.

[lidex]

Can you post the output of these terminal commands for me please:

uname -a
aplay -l
cat /proc/asound/version
head -n 1 /proc/asound/card*/codec#*

Terminal="Applications->Accessories->Terminal"
Please also include the make/model of your PC/Laptop.
Please post text output using code tags (the # in toolbar)

[X-Legs]

I have an Apple Macbook Pro 4,1. Detailed specs here.

uname -a

Linux Macbuntu 2.6.32-22-generic #33-Ubuntu SMP Wed Apr 28 13:27:30 UTC 2010 i686 GNU/Linux

aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC889A Analog [ALC889A Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC889A Digital [ALC889A Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

cat /proc/asound/version

Advanced Linux Sound Architecture Driver Version 1.0.23.
Compiled on May 21 2010 for kernel 2.6.32-22-generic (SMP).

head -n 1 /proc/asound/card*/codec#*

Codec: Realtek ALC889A

[lidex]

Try this. Using a Terminal="Applications->Accessories->Terminal"
Open this file for editing:

 gksudo gedit /etc/modprobe.d/alsa-base.conf

Insert this line at the bottom:

 options snd-hda-intel model=macpro

Save. Close. Reboot. Check your levels in alsamixer.

 alsamixer

Press <F6> to select the correct soundcard.
Press <F3> to show playback levels. <F4> selects capture levels [or use <Tab>]
Use the left/right arrow keys to select and up/down arrow keys to change levels. <M> to mute/unmute.

If this is Rev3, then this option instead:

options snd-hda-intel model=mbp3

[X-Legs]

The microphone is clearly responsive on Line In, but the voice is still VERY soft, even with everything maxed in Alsamixer. I also get some noise in the mic.

[lidex]

My alsamixer gives options for changing inputs. In the screen below you see two elements to the right (in capture mode) showing 'mic'. These are input selectors. Highlighting and using up/down arrows toggles between line/front mic/mic. This is maybe easier to edit in gnome-alsamixer using the "Edit > Sound Card Properties' menu to enable first. Perhaps you have a mic boost somewhere or you need to disable eapd.