Recording Workshop


Topics This Week

Microphones

If you plan on doing any type of live recording with your laptop, the first thing you'll need is a microphone. As the first link in the audio chain, a microphone acts as a kind of measuring device which outputs a small, continuously varying AC voltage in response to the changes in atmospheric pressure caused by any sound disturbance.

Performance Characteristics

There any many makes and models of microphones, each with it's own set of characteristics. When evaluating different microphones, there are three important factors to consider:

  • Frequency response - The range of frequencies a microphone will pick up.
  • Polar Pattern - Indicates how sensitive a microphone to sound coming from different directions.
    • Omni-directional: picks up sound equally from all directions.
    • Cardioid: Picks up sound from a single direction (on-axis).
      • Super-cardioid
      • Hyper-cardioid
    • Bi-directional: Picks up sound from two opposite sides.
  • Microphone Types:
    • Dynamic: Relatively inexpensive, rugged. Exhibits a "proximity effect." e.g.: Shure SM58
    • Condenser: Very sensitive to fast transients and high frequencies. Requires a source of DC power to operate.
      • Electret Condensers are generally cheaper versions and come with a charged plate that will lose its charge over time. Generally requires a DC battery to operate a small preamp.
      • Most professional Condensers require a Phantom power supply. e.g.: AKG 414
    • Ribbon: "smooth" sounding, traditionally somewhat fragile.
    • PZM: Contact microphone which uses another surface as a diaphragm.

These three factors are often integrated in a microphone's performance characteristics. When shopping for a microphone, look at these specifications, think about what the microphone will be used for, and choose accordingly. Manufacturers will often make suggestions on applications for their products, and trade publications, such as Electronic Musician, will often have articles and reviews.

Suggested Additional Reading: For a more detailed overview of microphones, read this article from the Electronic Musician archives: Building a Microphone Cabinet on Any Budget; Electronic Musician; September 2000.

Recording Audio with a Computer

Audio Signal Flow Beyond the Computer

In order to understand the various ways we might configure additional hardware components, we must understand how audio moves between devices.

Audio signals may exist in the analog domain as electrical voltages carried along copper wires. Audio may also be represented in the digital domain as numbers and transferred either as electrical signals (on or off pulses) on copper wire or as light pulses through fiber optic cables.

In addition, analog and digital audio signals may exist in various formats, each using a unique type of cable and/or connector.

Follow these links for a summary of audio connectors:


Audio Interfaces and Levels

Although your laptop is perfectly capable of recording and playing back digital audio, there are a number of possible upgrades that will yield better sound and offer a number of additional capabilities. Although sound cards have been a cost-effective way to upgrade tower-type computers, audio interfaces such as the MOTU 828mkII and the Pro Tools M-Box offer many advantages. These include:

Follow this link for more background on different types of computer audio connections.

As you expand your capabilities, one important consideration will be the matching the input and output levels of various hardware audio tools. Follow this link for some background on Audio Levels.


This Week's Assignment: Final Project

This week, get started on producing your final project for the semester.

Choose a piece of music in any style, original or not, and produce an arrangement using either GarageBand or Reason. If you use GarageBand, which supports audio recording, you are able to add an instrumental or vocal recording to this project. This would be a great opportunity to produce a demo of something you have written or of your performance skills. If you choose Reason, produce an instrumental arrangement. In either case, audio recording is not required to successfully complete this project.

Your project should fulfill the following requirements:

  1. The project should be at least one minute in length, at least once through the form of the piece you choose. In the case of a twelve-bar blues, you will need to repeat the form. For this project, the length can exceed one-minute if you would like, but please make sure that there is a good musical reason for this. Do not simply repeat sections to make the project longer. A longer project will not necessarily get a better grade.
  2. The project will include the following musical parts:
    - Melody
    - Keyboard accompaniment
    - Drums
    - Bass
    - Additional sequenced percussion or a percussion loop.
    - One example of a looped musical part, either an Appleloop or REX file, depending on the application you choose.
  3. The drum part should be done using MIDI sequencing techniques, not a loop.
  4. The drum part should demonstrate some type of variation. Use fills to set up each
    new section. Do not repeat a single one or two-bar pattern.
  5. All musical parts should work with each other rhythmically. Make sure to use quantization where needed.
  6. Choose to use loops wisely. Do not base the project on loops. Use them to add spice to an arrangement, not to define it.
  7. Name all the tracks that you use in the project.

Review Questions


Recording Workshop Vocabulary

ADC
Analog
Audio interface
Cardioid
Condenser microphone
Dynamic microphone
Omni-directional
Phantom power
Polar pattern
Proximity effectDigital
Frequency Response
Zero-latency monitoring
Plug
Jack
Sound card
Breakout box
Line level
Microphone level
Preamp

PCI card
USB
ADAT light pipe
Firewire