A microphone is the device which picks up the sounds made by your musicians, so it is an extremely important component of your rap studio. A microphone will require a preamp, which boosts the signal in advance of it getting to your recording device. Another useful accessory for a microphone is a pop shield, which attaches to the microphone stand and sits between the microphone and the lyricist's mouth. A pop shield reduces the drastic effect of certain consonant sounds, such as "p" and "s."
Samples provide the backbone of many rap songs. A sample is the reproduction of a small amount of previously-recorded sound. Through a use of samples, rap songs become sonic collages. One of the most popular sampling tools is the Akai Music Production Center (MPC), which presents the user with an array of pads. The pads on an MPC are used to play sample clips which have been previously stored. Records are one of the most frequently used sample sources. However, samples can come from any audio source. Many computer-recording tools have sample banks available, and the computer itself can be used as a powerful sampling instrument.
Ultimately, you will need to preserve the sounds in your studio. This is done with a recording device. One of the most common devices for recording in a modern studio is the computer. If you are going to use a computer for recording, you will need to also have an audio interface to convert incoming sound to a format that your computer will recognize. Even if you will not use a computer to record sound, it is useful for a number of other functions in a studio. A common alternative to computers, and a popular medium before them, is the reel-to-reel tape machine. While recording to tape provides the benefit of an analog sound recording, it is not as easy to edit as computer recording.
It is helpful to have other instruments in your studio. Even if your background tracks will be comprised mostly of samples, you never know when the inspiration to add original sounds will strike. A drum set, keyboards, a guitar, and a bass are good basic instruments to have in a studio.
In order to prevent sound from bleeding in your studio, you will need some sort of insulation to block and redirect sound waves. Insulation around outer walls is important for both the containing of sound within your studio and the blocking of outside sounds. Portable baffles are also important. In the event that you are recording more than one thing at a time, you may need to place baffles in between the sound sources and microphones, so that each microphone picks up sound mostly from a single source.
Headphones are essential to have in the studio if you are doing any sort of overdubs. Overdubbing is the process by which sounds are layered onto already-recorded sound. A rapper's vocals are almost always recorded on top of a pre-existing background track. The rapper must be able to hear this track in his/her headphones while s/he is rapping.
Monitors are speakers for listening back to the sound you record. They are useful both during the recording process and during the playback of recordings.
A mixing board is a console at which you can adjust the levels of multiple incoming and outgoing audio signals. Mixing is usually done after the sounds have been recorded, but is an essential part of the production of a song. While many computers have virtual mixing boards, the physical device allows for a more fluid mixing process.