Griffin iMic Linux Support

By Jochen Voss, last updated 2011-08-31

The Griffin iMic is a simple USB sound card. It is mostly used as an USB audio adapter for Apple computers which lack built-in sound support (for example the PowerBook G4 has no microphone input) but the iMic also works fine with other computers. This page summarises the Linux hardware support for the device. If you have questions or additional hints, feel free to contact me.

Summary

Linux support for the Griffin iMic is very good.

action	status
playback	works
recording	works
ALSA controls	work as expected easy to understand

Table 1. This table summarises the Linux support for the Griffin iMic USB audio adapter.

Technical Information

The iMic is a small, disk-shaped device, approx. 5cm across and 1cm high. It connects to an USB port and provides two 3.5mm mini-jack connectors to connect a stereo input and a stereo output device each. You can switch the input to be either line-in or microphone. The output can either be connected to external speakers or to a headset.

The USB vendor/product ID of the device is 077d:071f. From the lsusb output one can see that the iMic registers with the system as a standard USB audio device. The supported sampling frequencies range from 6400Hz to 48kHz for both input and output.

ALSA support

The following data corresponds to ALSA version 1.0.12rc2 together with the Linux kernel version 2.6.17.7. Hints on how to set up and use ALSA can, for example, be found on my ALSA web page.

The device is supported by the usb-audio ALSA driver. The entry in /proc/asound/cards is

 0 [system         ]: USB-Audio - iMic USB audio system
                      Griffin Technology, Inc iMic USB audio system \
                        at usb-0000:00:10.2-2, full speed

The corresponding device files in /dev/snd show one playback device and one capture device as expected:

crw-rw---- 1 root audio 116,  0 2006-08-06 20:07 controlC0
crw-rw---- 1 root audio 116, 24 2006-08-06 20:07 pcmC0D0c
crw-rw---- 1 root audio 116, 16 2006-08-06 20:07 pcmC0D0p
crw-rw---- 1 root audio 116, 33 2006-08-06 20:07 timer

Mixer Settings

Alsamixer shows the following controls for the device.

Playback Controls

Bass: mono slider: controls the low frequencies.
Bass Boost: mute/unmute: allows to boost the low frequencies for low volume.
Treble: mono slider: controls the high frequencies.
PCM: stereo slider with mute/unmute: the master volume control. Even when this is set to zero the sound is still audible, but not very loud.
Auto Gain Control: mute/unmute

Capture Controls

Bass: mono slider
Treble: mono slider
Mic: mono slider

References

The iMic product page on the Griffin web page.