Computer Audio Input Problemsby Aaron Wardell
Computers are excellent multimedia multi-taskers. Not only do they display video, but they are capable of input, and output of audio in multiple formats. They can be hooked to a home stereo system or used on their own as audio workstations. When something goes wrong with your computer's audio input, it is important to understand how the sound technology in your computer works in order to troubleshoot, and solve the problem.
Sound cards are where all the audio input, output, and signal processing takes place. Most modern sound cards are equipped to handle 2-channel audio as well as 5.1 or 7.1 channel surround-sound audio. Although they have inputs for the different surround speakers, most surround-capable sound cards only have a few outputs. Newer sound cards may include other inputs as well, such as a digital audio input. Other features include front panel sound connectors, external volume controls, and sound enhancement software.
A typical computer sound card is usually equipped to handle audio inputs from one or two sources. Desktop computers typically have a microphone input, and a line level input. On modern computers, the inputs, and outputs are color-coded. The mic input is pink and the line input is blue. These inputs can handle microphones, and other sources with smaller, 1/8" jacks. If a professional audio source with XLR connections is desired, it needs to be hooked up to a preamp or mixing board first.
Desktop vs. laptop sound cards
Desktop sound cards have more inputs, and options available than laptop sound cards. While desktop cards feature multiple input types, and surround sound inputs, laptops only come with one input, and output jack. The output usually doubles as a line out and headphone jack, while the input doubles as a microphone and line input. In order to connect a microphone to a laptop's line input, it should have a 1/8" plug. More advanced microphones, such as condenser mics usually won't work with a laptop's default mic input.
Microphones made for computers draw enough power from the mic input, easy to use, and are fine for simple voice recording or videoconferencing . For professional recording, however, more equipment is required. A high-quality condenser microphone will need to be hooked to a preamp and/or a mixer before being plugged into the mic or line input of the sound card. Professional-quality microphones need extra power (called phantom power) and XLR inputs to operate, and most sound cards do not provide this.
When troubleshooting your inputs, it's advisable to use your computer's software to ensure a particular input is not muted or turned down all the way. Sound cards are sensitive to loud frequencies, so if the incoming signal is too loud you will experience distortion. When using analog red/white inputs and outputs, a Y-adapter may be necessary to convert the output into an 1/8" jack compatible with your computer. Similarly, if the output has a 1/4" jack, a different converter is required. SPDIF, coaxial, and other digital inputs require cables made specifically for transferring digital audio.