1. Dr. Tim Collins T.Collins@bham.ac.uk www.eee.bham.ac.uk/collinst/music
EE2F2 – Music Technology
Dr. Tim Collins

2. 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

3. A Brief History 1877 Edison invents the ‘phonograph’ 1928
‘Ondes Martenot’ invented
1933
Alan Blumlein patents stereophonic sound reproduction
1937
‘Magnetophon’ developed in Germany by AEG
1963
Philips introduce the compact cassette
1969
‘Minimoog’ is launched
1978
Philips introduce the compact disc
1982
MIDI specification is announced
1983
Yamaha DX7 digital synthesiser is launched
1986
Steinberg launch a 16 track sequencer for the Commodore 64

4. 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.

5. Mics and electronic sources
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.

6. 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

7. Four-Track Example Track 1 - Blank Drums Track 2 - Blank Bass Guitar
Piano
Flute
Track 4 - Blank

8. 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

9. 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.

10. Microphones Condenser (or capacitor) Microphone Dynamic Microphone
Diaphragm moves due to sound waves
Capacitance and thus voltage change
Diaphragm
Fixed earth plate
Audio output
d.c. bias voltage
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

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

12. 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).

13. Mixing
Frequently Asked Question:
“What do all those knobs do ?”

14. 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.

15. 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.

16. 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.

17. 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

18. 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