EE2F2 Music Technology

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EE2F2 Music Technology

• Dr. Tim Collins
• T.Collins_at_bham.ac.uk
• www.eee.bham.ac.uk/collinst/music

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Introduction

• Course content
• How modern technology is used by musicians
• Recording studio technology
• Multi-track recording and mixing
• Effects processing
• Computerisation
• Performance technologies
• Electric instruments
• Synthesisers and Samplers

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A Brief History
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Recording Technology

• Simplest scenario single microphone, recorded
  straight to tape.
• More common several performers recorded
  separately and then mixed together later.
• We will look at the key elements in the audio
  signal chain
• Microphones / electronic instruments
• Mixers
• Multi-track tape recorders
• Effects
• We will also look at the use of computers for
  MIDI sequencing, and digital audio.

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The Audio Signal Chain
Mastering
Mics and electronic sources
Track laying mixer
Multi-track recorder
Mixdown to stereo
Stereo recorder

• The audio signal chain contains all the steps
  between the original performance and the final
  distribution.

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Multi-track Recording

• These days, music is rarely recorded in one
  take except for
• Live performances
• Classical music
• Usually, songs are built-up from several parts
  using a multi-track recorder
• A multi-track recorder can
• Record lots of separate sounds independently
• Play them all back at once

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Four-Track Example
Track 1 - Blank
Track 2 - Blank
Track 3 - Blank
Track 4 - Blank
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Audio Signal Chain Components
Mastering
Mics and electronic sources
Track laying mixer
Multi-track recorder
Mixdown to stereo
Stereo recorder

• Over the next few weeks we will look at the audio
  signal chain in more detail. In particular
• Microphones
• Mixing
• Multi-Track Recording
• Mastering
• Computerisation and Automation

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Microphones

• Microphones are transducers that convert
  acoustical energy (i.e. mechanical vibration)
  into electrical energy.
• Two main types used for music
• Electromagnetic Dynamic and ribbon designs, work
  by electromagnetic induction.
• Capacitor Condenser design, works by changing
  the shape of a charged capacitor.

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Microphones
Magnet
Diaphragm
Coil
Dynamic Microphone Diaphragm and coil move due to
sound waves Current is induced in coil

• Regardless of the mechanism, important parameters
  are
• Frequency response
• Sensitivity
• Directional response

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Example - Shure SM58
Dynamic (moving coil) microphone popularly used
for vocals. Sensitivity -54.5 dBV/Pa (2.8
mV/Pa)
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Signal Levels

• Even the most sensitive microphones have
  sensitivities no higher than around 10 mV/Pa.
• When held close to the mouth of a singer, a
  typical sound pressure will be around 1 Pascal.
• So, even the most sensitive microphone will
  produce a signal of around 10 mV in amplitude.
• Typically, for common microphones, the signal
  level would be around 1 mV (depending on how loud
  the singer is and on the microphone positioning).

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Mixing
Frequently Asked Question What do all those
knobs do ?
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Mixers

• In the simplest terms, all a mixer does is to add
  together two or more input voltages.
• In practice, it must also provide gain controls
  in order to
• Correctly mix signals from different sources,
  e.g.
• Line level signals (1 V) from electronic
  instruments
• Mic level signals (1 mV) from microphones
• Balance the different parts of a mix.
• Actually, most mixers perform several other
  functions as well. We will cover them in a later
  session.

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Tape Recorders

• There are two types of tape recorder in the audio
  signal chain.
• Stereo (two track) recorders, similar to domestic
  hi-fi tape decks.
• Multi-track recorders (anything from 4 to 24
  tracks)
• Analogue and digital versions of both types are
  available.
• These days, mostly digital machines are used.
• In fact, magnetic tape is often not used at all.
  Hard disk recording is becoming more common.

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Mastering

• The master tape containing the final stereo mix
  must be duplicated in different ways for
  different distribution media.
• Vinyl LPs require special equalisation
  (filtering)
• Cassette masters are made on special tape used
  for high speed duplication
• CDs require the addition of codes to mark the
  start and end of tracks
• These processes are known as mastering.

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Computerisation Automation

• Computers have been gradually introduced into the
  recording studio to automate certain tasks
• Triggering drum machines with preset patterns
  (sequencing)
• Changing fader levels on a mixing desk to preset
  levels at the right time
• Triggering (remotely playing) electronic
  instruments (via MIDI)
• Digitally recording onto hard disk
• Generating synthetic sounds using software
  synthesisers
• Generating special effects in software
• Replacing most of the equipment in a conventional
  studio with virtual software equivalents

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Summary

• In this course, we will be looking at how modern
  technology has affected musicians in terms of
• Recording technology
• Synthesis and sampling technology
• The basis of most contemporary recordings is the
  multi-track concept.
• This is traditionally realised using analogue
  multi-track tape machines.
• Nowadays it is often done digitally in software.
• Next time Stereo and Multi-track recording