IPad – USB Stereo Microphone for iPad

On new Macbook Pros, there is no microphone input. What you have is a line-level input. Microphones that do not have integrated power and amplification (all cheap computer microphones/handsets) will not work when connected to the line-level input.

The connectors are exactly the same, but on the line input there is stereo input and ground, and on the microphone input there is mono input, voltage reference and ground. The input level is also different, with line level at around 1V and microphone level at 10-100mV.

To resolve the problem, you need to get one of the following:

• a USB sound card which has a proper microphone input circuitry,
• a powered, amplified microphone that can be used with line-level input, or
• a microphone preamplifier.

See also:

• http://www.hobby-hour.com/electronics/computer_microphone.php

• http://en.wikipedia.org/wiki/Line_level

iOS allows the currently frontmost app to control the audio session and to configure the audio input for its use. So you would have to look in each app to see if it has any settings for audio while it is running.

There is an API for an app to request an input sample rate. However there currently appears to be no public API for an app to set the hardware audio input gain.