There are plenty of choices to make because there are plenty of different methods to get audio into your computer. I would recommend beginning with a basic understanding of at least the most basic components needed. These are microphone, preamp, interface, and recording software.
Microphone:
Obviously we need a microphone. This simply converts the sound into an electrical signal. The two most popular types of microphones are dynamic and condenser.
Dynamic Mic: Has a magnet and moving coil built in to generate its own electricity. Nice for general use but can lack some accuracy in sound, (although, this can be a good thing depending on what you are recording.)
Condenser Mic: Does not have a magnet built in. Relies on a voltage from the preamp to function, (called phantom power.) Picks up more high frequency than dynamic mics. Generally more sensitive to sharp rises in volume (transient peaks) than dynamic microphones.
Pre-amp:
Almost all microphones put out a signal that is very weak, (unless the sound being recorded is extremely loud to begin with.) So, we usually need a piece of equipment to boost the signal up to a more "usable" level. This device is called a mic pre-amplifier or preamp for short. The preamp volume knob should only be turned up as much as necessary to show adequate signal strength on the recording meters.
Once the microphone signal is made stronger by the preamp it is referred to as being at "Line Level." This basically means that it is strong enough to go through the rest of the audio recording system without any problems.
Ideally the mic preamp should not change the way the microphone sounds other than making it louder. If it actually changes the character of the sound, engineers refer to this as "color." Some feel colorization is a good thing and some feel it is a bad thing. That is for you to decide based on desired results. Some preamp manufacturers use colorization and distortion as a selling point referring to it as audible warmth.
Interface:
The signal from mics (and from preamps) is considered to be analog in nature. This means that it is based on moving electrons that keep changing direction. Computers cannot deal with this type of signal because they are digital in nature. In other words they expect the signal to be a series of short pulses of electricity (which represent numbers) rather than a flow of Alternating Current. Because a "digital" microphone has never been invented, we need a box to convert the signal into the digital format. Enter the A/D converter. The A/D stands for Analog-to-Digital. (There are also D/A converters that work in reverse, changing digital-to-analog.)
The word Interface refers to any device that can provide this connection or bridge between the analog world and the digital world. If you record anything in a computer, it must first go through some sort of interface for translation.
Quite often the mic pre-amp and A/D converters are built together into one convenient box. Some mics (such as usb mics) have the pre and converter all built into the body of the mic. If you purchase separate components you generally have greater control over each part of the system and room for higher quality parts.
If the interface is external from the computer, the signal can be sent into the computer through a variety of different cable/plug types. Some types include; Firewire, USB, S/PDIF, PCI card, PCMCIA card, and Toslink/Lightpipe.)
Drawbacks to Firewire:
Not all computers have firewire plugs. Those that do may offer 4 pin or 6 pin plug types. The two extra pins supply dc voltage to power the connected device. The 4 pin plug was originally designed for digital cameras which can supply their own power. Otherwise the plugs are identical as far as the first 4 data pins are concerned.
Drawbacks to USB:
All data I/O functions are handled by the computer's main cpu chip. If the machine lacks memory, has other USB devices connected, or is burdened with other background duties, you will likely experience lag if recording higher track counts.
Drawbacks to S/PDIF:
Limited to only two channels. This means you could only record a maximum of two microphones simultaneously. If your intentions are to record a full band, a mixer may need to be added to blend all channels down to two.
Drawbacks to Toslink/Lightpipe:
These operate using pulses of light sent through a transparent tube that looks like wire. It can support up to 8 separate channels in a single wire such as with ADAT. It requires a sending unit and a receiving unit at either end of the optical wire. Many computers do not have a receiving unit built in. If the wire would become bent, broken, or obstructed by dust, it may stop functioning.
Drawbacks to PCI cards:
In most cases you would need to open the computer case to install these. They come in several different types that are not always compatible with each other. This can be very confusing to a beginner as some types even operate at different voltages. The correct type must be matched with your motherboard slots.
Cheapest alternative:
You may be able to use the factory sound card that comes built into your computer. It actually is an A/D converter, but it probably only has two channels, Left & Right. Sound cards often include two types of plugs. One is MIC IN and the other is LINE IN. The MIC IN expects the incoming signal to be very weak, such as that from a cheap computer mic. The LINE IN expects the signal to be the stronger Line Level, such as that from a pre-amp.
I hope this helps a little.
