Recording Guitar...

 

First you need a way to get audio into your computer.  The ideal way is to get an audio interface that has a Microphone preamp for recording acoustic guitar, vocals, drums, etc. and Instrument input for recording electric guitars and basses. These don't have to be expensive, and many are custom designed for the guitarist.  They might come with digital models of guitars and amps built right into the interface or in the software that comes in the package. 

Over the past few years musicians have been opting for Audio interfaces instead of the internal sound card.  This is a breakout box that sits outside the computer and connects via USB or Firewire.  These interfaces typically have built in microphone pre-amps with XLR mic connectors, instrument inputs, headphone jacks etc.  They often come with Asio Drivers and recording software as well.  You can also get an inexpensive USB to Audio interface for recording guitar but you are limited by the quality of your computers sound card, normally not that good.  Some brands of audio interfaces i have used and recommend are Lexicon, Line 6, PreSonus.

Recording Acoustic Guitars with a Microphone..

Once you have your audio interface or soundcard and mixer setup, you need to hook up the microphones.  Microphones I tend to like for recording steel stringed and nylon stringed guitars are of the small condenser type.  My personal favorite is the Shure SM81, which captures a wonderful wooden sound with exceptional clarity.  I like this mic because it is long and thin.  This allows for placement close to your strumming hand pointed at the area between the bridge and the sound hole.  A larger condenser mic will sound almost as good if you can get it to the right location without knocking it with your hand.

It takes a bit of experimentation to find what woks best for your style.  The guitar can be hugely dynamic and if you are too close you can overdrive the preamp, which is not a good thing.

Many of the "New Age" guitarists get their sound by recording in stereo.  Typically, one uses the classic "XY" technique with ideally 2 matched small diaphragm condenser microphones.  I find you can use different mics, sometimes with surprising results.  Using this technique the mics are put at a 90 degree angle.  The Mic on the right will point towards the sound hole and the one on the left will point at the bridge. 

Record through a direct box to the audio interface.

Recording Electric Guitars can be done direct.  By that I mean without a microphone and amp.  Today, with a good audio sequencer like Sonar or Cubase SX there are many  to do so. By recording a clean sound you can add effects later with plugins.  this gives you the flexibility to audition many different effects in your mix.  The problem you may have going through the instrument input on your Audio Interface is hum, especiall if your using humbucker pickups. 

The time honored solution for recording direct is to convert the HiZ signal to a balanced XLR mic signal with a cool device known as a direct box.  The direct box, in combination with the mic preamp on the board, provides a crystal clear hi-output signal suitable for recording.  There are many models of direct boxes, some with amp simulators, and now some with digitally modeled amp simulators.  I simply use an inexpensive Behringer DI100 and enjoy the hundredfold improvement in the signal to noise ratio.

Sometimes nothing will do better than the sound of a recorded amp.  As we know, amps have particular gain stages that allow for a wide variety of crunchy tonalities.  Digitally modeled amp simulators can go a long way to creating the beloved buzz, but not with the same fluidity, organic-nature or ok, lets say it, "warmth".  The micing of a guitar amp opens a number of things to consider. You do have to boost the initial gain, so the amp delivers the preferred amount of overdrive.  Small amps actually can do as good of a job as a stack.  To record your amps sound you need a good mic for the job, not a great $2,000 condenser, but a common Shure SM57 dynamic mic works great.  Placement of the mic is also a variable.  I like to stick the SM57 right up about 2-3 inches from the cone, that way I get a little more bass in it due to the proximity effect of this mic.  If you want more of a "room tone" you can begin by slightly angling the mic away from the cone towards a wall.  Indeed, careful experimentation can give you some unique ambient tones.

The Amp to Mic kind of recording chain also benefits from a compressor/gate.  If you turn on your amp with nothing connected and it hums, you will need a gate to get rid of that part of the signal.  The Compressor can give you a more sustained, balanced audio signal that is optimized for the recorder. 

Over the past few years there have been a landslide of virtual guitar amp simulators on the market.  These work by taking the direct sound of your guitar and running them through a mathematical model that imparts the sonic characteristics and artifacts of particular amp models.  These devices usually have some effects added in, such as the typical chorus, flange, delay and reverb in various combinations that we have grown to love.  There are many others out there. The Line 6 Pod Farm is what I use.   Do these units really sound as great as a vintage amp as they claim?  Yes and no.  In the mix with other instruments, few will be able to tell.  The great advantage of these is that one can record clean and apply the modeler later, as an insert on a mixing board.