Analog Recording

A Brief History of Sound Recording

Before actual sound recordings existed, several mechanical formats were developed to reproduce music. These included devices such as:

Musical Clocks (1598)Barrel Organs (1600s)Barrel Pianos (1805)Musical Boxes (1815)Player Pianos (1876)

Musical Clock

Barrel Organ

Barrel Piano

Musical Boxes

Player Pianos

The first recordings

The first two formats for recording sound were :

1) Cylinder Phonograph (1877) by Thomas Edison

2) Gramophone Record (1889) Emile Berliner

Cylinder Phonograph

Edison’s first sound recording

Gramophone Record

Emile Berliner with Gramophone record player

Development of Electronic Formats

Throughout the 20th Century many different electronic inventions were made to make the recording and reproduction of sound more accurate and efficient.

Telegraphonemagnetic wire recording

by Valdemar Poulsen(1898)

The first answering machine

Triode vacuum tube by Lee De Forest Amplification

Audion (1906)

Regenerative Circuit (1914-1922) by Edwin Armstrong Radio

Condenser Microphone (1917) by E.C. Wente of Bell Labs

late 20’s condenser mic

Victor Talking Machine (1924) Bell Labs

Columbia Phonograph Co. (1924) Bell Labs

Ribbon Microphone (1925) RCA

Sound-On-FilmRCA Photophone (1925)

Stereo recording patented (1931) Alan Blumlein -EMI

Blumlein Pair Array(2 crossed Figure-8s)(Small arrows indicate front of individualmicrophones, large arrow indicates front of array.)

Marconi-Stille Recorder-steel tape recording (1932) used by BBC

Telegraphone/Magnetophone-acetate tape recording (1935) BASF

Shure Unidyne-cardiod dynamic mic (1938)

Ampex Model 200 (1948) ¼” tape and 10 ½ “ reels – Jack Mullin

Microgroove Long Playing Records 33 1/3 RPM (1948) Dr. Peter Goldmark-Columbia Records

45 RPM single (1949) RCA Victor

Multi-Track Tape Recorder-modification of Ampex Model 300 (1950) –Les Paul

Ampex 1” eight track tape developed for Les Paul (1954)

8 Track Sel-Sync recording (Selective Synchronous Recording)-Les Paul (1956)

Stereo Records (1958)

Mixer – Rupert Neve (1961)

Compact Cassette (1963)

8-track tapes (1964)

Automatic Double Tracking (ADT) (1966)

synchronizing two 4 track machines Ken Townshend at Abbey Road

Ampex MM-100016 track recording (1967)

TASCAM, TEAC, OTARI , AMPEX and STUDER - 24 track recording (1973)

MCI -32 track recording at 20 IPS –inches per second(1978)

Tascam Portastudio – 4 tracks on a cassette (1979)

An Introduction to Tape Recording

How does analog tape recording work?

Tape Recording An acoustic sound source creates waves in the air.

These waves are continuously varying in air pressure. A microphone capsule responds to changes of air

pressure. As the diaphragm moves a variance in the flow of

electrons is induced. This variation in the flow of electrons from the microphone is amplified and routed to the record head.

The record head responds to the microphone signal by converting the electrical signal into a continuously changing magnetic flow.

Changes in magnetic flow are imprinted on the recording tape and stored for playback.

Tape Recording (continued) The playback head is constantly in a state of being

magnetized by the tape. The tape induces a continuously varying magnetism in the playback head.

The varying magnetic flow from the play back head is converted into an electrical signal that is sent back to the mixer or input of the power amp.

The power amplifier boosts the level of the original signal enough to move a speaker cone back and forth in the same way that the microphone capsule was moved in the first place.

As the speaker cone moves back and forth it creates continuously varying changes in air pressure (waves).

The speaker cone movement should be an exact replica of the waves created by the original sound source as it was captured by the microphone.

Why do many audiophiles still prefer analog tape recordings?

Analog recording is considered to be more accurate than digital recording because it captures a continuously variable change in air pressure. This system reflects the original waveform in the most accurate way.

The anatomy of the analog tape mechanism

There are several significant disadvantages to analog recording

Poor signal to noise ratio Cumbersome and bulky equipment is

involved Tape degrades with each progressive

play over the tape head The equipment is mechanical

therefore it is prone to failure. Lots of care and maintenance is

needed (head cleaning, degaussing)

Disadvantages (continued) Editing of parts is difficult (punching in and out) Editing of the master is done with a razor blade.

There is no undo!! Tape is fairly expensive ($175 for 24 track tape that

holds only 16 minutes) Requires special care when storing (“tails out to

avoid print through” and also under specific temperature and humidity conditions) Tapes should be stored in a cool, dry environment between 50° F and 70° F, 20% to 45% relative humidity. Lower numbers are better for longer-term storage.

Disadvantages (continued) Cueing to a specific position on a track is

more difficult. Automation of mixing functions is rare and

expensive. Each successive copy of the original has a

poorer sound quality.

Despite these pitfalls, many musicians still prefer analog recording.

The quality and capability of analog tape recording is determined by several factors

Width of the tape:

i) cassettes are 1/8” wideii) reel to reel tapes are 1/4”, 1/2” , 1” or

2” wide

Factors that determine quality and capability of tape recording (continued) Speed of the tape:

i) cassettes (1 7/8 IPS –inches per second)ii) 4 track cassettes (3 ¾ IPS)iii) ¼ inch reel to reel (7 ½ IPS)iv) ½” and 1” reel to reel (15 IPS)v) 2” reel to reel (30 IPS)

A faster tape-speed produces a higher quality recording

Factors that determine quality and capability of tape recording (continued) Number of tracks: i) cassettes (8 tracks at most…usually 4)ii) ¼ “ reel to reel (varies from 2 to 8 tracks)iii) ½” reel to reel (varies from 2 to 16 tracks)iv) 1” reel to reel (8 or 16 tracks)

2” reel to reel (16 or 24 tracks)

Fewer tracks on a wider tape usually mean that there will be a lower chance for the occurrence of cross-talk (fringing) between tracks. This is when signals from one track bleed over to another.

Factors that determine quality and capability of tape recording (continued)

Factors that determine quality and capability of tape recording (continued)

The type of magnetic oxide particles found on the tape:

i) Iron Oxide ii) Chromium Dioxide

Chromium dioxide provides better signal to noise ratio and a wider dynamic range

Factors that determine quality and capability of tape recording (continued)

Factors that determine quality and capability of tape recording (continued)

Amount of Wow and Flutter:This is a measure of the change in recorded frequency due to the variation in tape speed of the recorder. Wow and flutter cannot be corrected after the recording is made so you are stuck with what you have.

Factors that determine quality and capability of tape recording (continued) Type of Noise Reduction that is used:

Dolby Laboratories created several methods of reducing tape hiss on analog recordings. Dolby developed an encoding and decoding system of noise reduction.

Types of Noise Reduction:

a) Dolby B-type Noise Reduction: 10 dB of noise reductionb) Dolby C-type Noise Reduction: 20 dB of noise reductionc) Dolby S-type Noise Reduction: 24 dB of noise reduction and

reduces low frequency noise by 10db. d) DBX Noise Reduction- Professional level technology that involves

compression as a portion of the signal is boosted to avoid tape saturation and distortion. This system reduces tape hiss while still maintaining a widedynamic range in the recording.

Factors that determine quality and capability of tape recording (continued)

Interesting Analog Recording Tricks

Variable speed recording: Recording sounds at a slower or faster tape speed allows the artist to record a track at half or double speed to alter the tempo and pitch of a part by an octave up or down. Popularized by Alvin and the Chipmunks, Mike Oldfield and Les Paul.

Ex. Sombreros (A. Shoesmith)

Interesting Analog Recording Tricks (continued)

Backwards masking: Flipping the tape over and recording a part backwards will yield interesting results when flipped back over.

Ex.1 Pink Floyd’s Empty SpacesEx. 2 Beatle’s Rain