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Digital vs. Analogue

Sound can be recorded in either an analogue or a digital format. Digital recording only became a possibility in the 1980’s, so up until then, everything was recorded in an analogue format.

The edexcel definition of analogue is “when a signal or equipment uses a continuously variable physical quantity.” What this really means is that an analog audio signal is an exact copy of an original audio signal, whereas a digital signal represents this original signal in terms of digits or numbers.

Pros and Cons of Analogue

✔️ More pleasant ‘warm’ sound than digital signals/processing.

✔️ Analogue recordings can be more accurate due to changes in air pressure being captured exactly as recorded.

✔️ Analogue also uses less bandwidth and the size of the project doesn’t have any effect on the speed of your equipment (this is a problem with computers/digital recording)

✔️ With analogue you have to rely on your ears to listen out for mistakes, rather than looking at sound waves on a computer.

✖️ Analogue recordings are much harder and more time consuming to edit.

✖️ Unwanted noise like tape hiss and equipment noise is hard to get rid of.

✖️ Any edit that you make is permanent/can’t be undone.

✖️ Analogue equipment can take up lots of space and not portable.

✖️ Every time a copy of the audio is made from the original tape, the quality in sound deteriorates a little. This also applies each time the track is played.

For pros and cons of digital, see this page.

Characteristics of Analogue Hardware

• Clipping: There are two types of analogue amplifiers; the valve amp and the transistor or solid-state amp. When a valve amp is overloaded, it does what is known as soft clipping. When a solid-state amp is overloaded however, it does what is known as hard clipping. The soft clipping of the valve amplifier gives the signal a 'warmer' sound.

• Saturation: Something else that gives analogue recordings their signature 'warm' sound is saturation. Saturation occurs when recording to tape. Tape saturation is “the effect of the aurally pleasing soft clipping caused by recording a signal to an analogue tape that is slightly overloaded.” Due to the nature of tape recording, you can get to a point where the tape can no longer hold any more amplitude, so the signal gets compressed and distorted in a nonlinear fashion, creating saturation.

• Artefacts: Analogue recordings can often have certain problems affecting the sound quality, which, although not necessarily desirable, plays a part in the distinctive sound of analogue recordings. These unwanted sounds are called artefacts.

For example, tape degrades over time, meaning that every time you play a tape, whether through a tape machine or through a cassette, the sound quality worsens. Another example of an artefact is wow and flutter. They are slight variations in pitch that can occur in analogue recording. Wow is a slower version of flutter. In tape machines, pitch variation occurs when the playback speed is inconsistent; the pitch is higher when the playback speed is faster and the pitch is lower when the playback speed is slower.

Analogue Recording

By the 1950’s, tape was the standard medium of recording. Prior to this, wax, foil, paper and lead had all be used to record sound, but once tape had been discovered, these methods fell out of use very quickly due to the fact that they suffered a lot of degradation on playback.

When you record to tape, the changing electrical signal from your microphone is ‘printed’ onto tape that is coated with magnetic metal oxide. The changes in electrical signal corresponds directly to the changes in magnetic charge along the tape.

When it comes to editing a signal that’s been recorded to tape, the only editing that you can do is cutting (literally cutting the tape) and splicing (joining bits of tape together). The video below demonstrates how this works.

It is also worth noting that, depending on how many tracks you are recording/what type of tape machine you're using, you will need to use tape with different widths.

The invention of the mono tape recorder had a significant impact on the music industry. Prior to its invention, music was only accessible to the general public through attending concerts or listening to a live performance, which were often quite expensive. The ability to record a sound and distribute it on a wide scale made music something that was accessible to everyone. It enabled people to hear music from cultures outside their own and kickstarted the growth of the web of musical styles that we all have access to today.

A final thing to add is that when recording to tape, the faster the tape is moving, the better the sound quality. In order to get the best sound without spending extortionate amounts of money on tape, music producers would quite often put a limit on the length of songs, normally around the 3 minute mark. This has had a lasting effect on the type and the length of music that we still listen to today.

Mono Tape Recording (1950 - 1963)

As the title suggests, at this time everything was recorded in mono ("a single sound source, speaker or channel").

At first, only one microphone would have been used so it was important that you to arranged the musicians very carefully within the room to ensure that the balance between the parts was right. Once mixing desks were more common place however, it was possible to record a group of musicians using multiple mics, get the balance right using a mixing desk and then record to tape. All of musicians would still have to play together but capture was more accurate and spacing was less important. This process is known as submixing.

✔️ Revolutionised the music industry. Mono tape recording allowed music to be accessible to more people.

✔️ Better medium than foil, wax, paper and other materials to record on. Suffered from less damage on playback.

✖️ Since there was no option for overdubbing (see below for more info on what this is), ensembles had to be recorded all together, which meant that even if just one musician made a mistake, the entire song would have to be re-recorded, or the track would have to be released with a mistake in it.

✖️ Editing was limited. If there was a point in the song where a cut could be made without anyone noticing, you could splice together two takes of a song, but this didn't happen all that often as it was hard to achieve a seamless cut.

Early Multitrack Recording (1964-1969)

Multitracking is “recording multiple audio tracks separately and then blending then after recording rather than mixing the channels prior to recording.” It was the invention of multitracking that made overdubbing possible, which is “the process of recording additional parts into a recording.”

The first multitrack recorder was built in 1954 by Ampex at the request of Les Paul. It had three tracks, which sounds like an odd amount, but it was useful because it allowed for the band to be recorded in stereo and for the vocalist to have their own track. By the 1960s, multitrack recorders were commonplace in recording studios and would have up to 4 tracks.

The only difference between mono tape recorders and multitrack tape recorders in terms of workings is that multitrack tape is split into a number of sections corresponding with the amount of tracks it is holding, eg. 4 sections for 4-track.

In the diagram above, different colours represent unique recording material. The stereo tape can either be used to record in stereo (eg. full band) or it can be used to record two unique mono recordings (eg. full band in mono on one track and a vocals on the other track). This can apply to the other tape formats as well (eg. four track tape can record four mono tracks or two stereo tracks).

In terms of recording, full band recordings were still common place. It was regular practice to record vocals to one track and split the rest of the band to the remaining tracks. The difference now, however, was that you could balance the tracks after they had been recorded. You could also now 'drop-in' and 'drop-out' of a take, meaning that if there was a mistake at one point of the song, you could record just that one part of the song again and splice the takes together. You could also record just one instrument again without the other musicians if need be, as long as the instrument was recorded on a track of its own and was well isolated during recording (if not well isolated, there could be spill from previous takes present on other tracks).

The invention on multitrack recorders led to the 'bouncing down' process becoming common practice in studios. Edexcel's definition of bouncing down is "the process of converting sounds to a new audio file embedding all processing applied to them. Normally multiple tracks into fewer tracks but sometimes used to print effects onto an audio track."

In the context of multitrack tape recording, bouncing down involves recording on to all available tracks on the tape machine, mixing these tracks together, creating a sub-mix, and printing this sub-mix on to a spare track on another tape machine. Once this second tape machine is full with more recordings/overdubs, these tracks can be mixed and bounced down to another tape machine, and, in theory, this process can repeat infinitely, giving you (theoretically) infinite tracks.

Given that multitrack recorders and bouncing down allowed for more channels, bands and producers started to add more parts to their songs. This was important for the development of popular music and soul music. Phil Spector lead the way with his ‘Wall of Sound’ technique, which intended to exploit the possibilities of the current recording technology and create abnormally dense orchestral textures.

✔️ Allows for stereo recording, meaning that music could be distributed and listened to with left and right information, making it a more immersive experience.

✔️ Multitrack recording and overdubbing allowed for more texturally dense music to be produced.

✖️ Once a sub-mix is committed to a new track, it is fixed and the mix cannot be changed.

✖️ Every time a sub-mix is bounced to a new track, the amount of tape hiss and noise on the recording is increased.

✖️ When bouncing, if the "receiving" machine was running faster than the original machine, the audio would end up sounding higher in pitch than it was when recorded.

Large-scale Analogue Multitrack (1968 - 1995)

Despite the fact that Ampex had been working on 8-track recording technology since the late-50s, it wasn’t until 1967 when the first 8-track recorder, the MM-1000, was made commercially available. From here, things progressed pretty quickly; later on in the same year, the 16-track version of the MM-1000 was released. By 1968, MCI had released their JH24 series which had 24 tracks, and this became the most widely used format in professional recording studios throughout the ’70s and ’80s.

It was at this time that synchronisation between tape machines improved, so it because common to link two 24 track tape machines together to have up to 48 tracks available.

In term of workings, the main thing that changed between early multitrack and large-scale multitrack recording machines was that track width increased. This was so that the tape could carry more tracks. The smallest width available was 1/4″ tape and the largest was 2″ tape.

When it came to recording, overdubbing was far more commonplace than it was previously. This increased separation on parts made it even simpler to re-record parts that had mistakes in or needed changing etc.

The main impact that the invention of the large-scale multitrack recorder was that it lead to large-format mixing desks being produced. These desks, often produced by SSL and Neve, came with their own distinctive sounding pre-amps, in-built dynamic processing and EQ modules. The sounds created by this hardware technology are so iconic that they have been emulated ever since by modern recording software.

✔️ Since more tracks were available, sub-mixing and bouncing down wasn't needed as much as it was before, which is an advantage as this process can increase the amount of tape hiss on a record.

✔️ Increased simplicity when it came to re-recording parts due to more tracks allowing for overdubbing to take place more regularly.

✖️ Doesn't produce recordings quite as cleanly as digital tape does. Click here to find out about digital recording.

Cassette

The cassette was released as a consumer product in 1961 by Philips, but it didn’t really take off as a consumer format until the mid-70s. They were hugely popular throughout the 80s, but when CDs became cheaper and more readily available in the 90s, the cassette quickly fell out of use and was largely obsolete by the 2000s.

The cassette works in a similar way to the tape recorders. Sound is recorded onto the tape in the cassette via record heads that cause the magnetic particles on the surface of the tape to be rearranged to represent the audio signal.

Cassettes are available in stereo (four tracks - two tracks for Side A and two for Side B) or in mono (two tracks - one for Side A, one for Side B). The tape in cassettes is always 3.81mm in width. In mono cassettes each track is 1.5mm wide, whereas the tracks in a stereo cassette are only 0.6mm in width with 0.3mm of space in between each track to avoid crosstalk.

Analogue Effects

Delay

There are two types of analogue delay; tape and bucket brigade.

Tape delay is created by recording a signal on to some tape that has been cut and spliced into a loop. The tape does a full loop and then the signal is played back over the playback/replay heads. The playback head is usually very close to the record head to ensure that there is no delay, but here the replay head(s) are far apart from the record head so that there is a time difference/delay between the record head output and the playback output.

The other type of delay is bucket brigade delay. When a signal is fed through the device, capacitors (or ‘buckets’) inside hold the signal for a set amount of time, and then, while synched to clock, the signal is moved on to the next capacitor, and so on and so on through all the capacitors. This has the effect of delaying the signal in time with a clock.

Reverb

There are two methods that you can use to create an analogue reverb; plate reverb and spring reverb.

Plate reverb entails feeding the recorded signal on to a large sheet of metal via a drive transducer, and then capturing the resultant sound at different points along the plate with pickup transducers. A transducer is “a device that converts between different types of energy.”

Spring reverb is essentially the same as plate reverb but instead of a plate, you feed the signal through a spring instead, using a drive transducer at one end and a pickup transducer at the other end.

Rotary Speaker

The original purpose of the rotary speaker was to recreate the sound of a pipe organ. Invented by Donald Leslie in the late 1930’s, the rotary speaker utilises the Doppler effect (a shift in pitch/frequency of a sound caused by the sound source moving either away from or towards the listener – think sirens on fast moving emergency vehicles) by having two horns spinning or rotating within a cabinet. Watch the video here for an example of what the effect sounds like on a guitar and some information about the development of the rotary speaker.

Vinyl Scratching

Scratching, also known as scrubbing, is a technique commonly used by DJs that entails moving a vinyl record back and forth on a turntable to produce percussive sounds.

Pitch Change

You can change the pitch of a signal on vinyl and tape by slowing down the playback speed on the playback device.

Reversing

You can reverse the playback on vinyl by making the record spin counter-clockwise. When it comes to tape, obviously you can do the same and play the tape backwards, but you can also do this at the recording stage and make the reversed signal part of your track. The Beatles were a big fan of this. Listen to the guitar solo of ‘Tomorrow Never Knows.’

Modular Synthesis

Modular synthesis is a type of analogue synthesis that is customisable. A modular synthesiser is made up of lots of little modules that can be connected with patch cables. The output of each module can be audio signals, control voltages or logic/timing signals.

If you want to learn a little bit more about this, watch this video:

Also, if you fancy having a go at modular synthesis but don’t have the money to throw at a hardware modulator (they’re expensive), software modulators are now available. Below is a link to download VCV rack, which I have used before and would recommend:

https://vcvrack.com

Electric Instruments

Pickups

A pickup is “a device that converts vibrations (magnetic, physical etc.) into an electrical signal for amplification and processing.”

Pickups work on the basis of Faraday’s law which states that a varying magnetic field will induce an electrical current into a conductor passing through its field. Every time you pluck a string on a guitar with a pickup, the vibrations of that string causes a change in the magnetic field (produced by magnets in the pickup), which induces a current in the wire coil.

There are two main types of pickup; single-coil pickups and dual-coil or humbucker pickups. Single-coil pickups have one coil of wire wrapped around a set of magnets, whereas dual-coil pickups have two coils wrapped in opposite directions around the magnets. One problem with single-coil pickups is that the magnetic field isn’t very strong so the output level is relatively low. Dual-coil pickups combat this by having two coils, therefore increasing the magnetic field strength and output level. Another problem with single-coil pickups is that they act as antennas, so can introduce interference into the signal. Dual-coil or humbucker pickups don’t have this problem, however, because the two coils are wrapped around in different directions and therefore have different polarities. This results in the hum being “bucked” and the string signal staying intact.

Electric guitar

The first electric guitar was invented in 1931 by George Beauchamp, and it was known as “the frying pan” due to its shape. It used a single coil Rickenbacker “horseshoe” pickup.

In 1936, the ES150 guitar was designed by Gibson. It is considered to be the first commercially available electric guitar. It had a single-coil pickup and it was hollow bodied. A problem with hollow bodied electric guitars is that they are susceptible to feedback, so in 1941 Les Paul started to experiment with solid-bodied guitars.

Paul presented his solid-bodied guitar prototype (known as “the log”) to Gibson, but there wan’t much interest in it until Fender started to sell their own solid bodied guitars. The first guitars to be released by Fender were the Esquire and the Broadcaster (later renamed to Telecaster). Off the back of Fender’s success with solid bodied guitars, Gibson decided to take up Les Paul’s offer and in 1952, the Gibson Les Paul was launched (pictured on the left). Something that made the Gibson Les Paul different to their Fender rivals was the use of the humbucker pickup.

Despite the success of the solid-bodied guitar, some guitarists were missing the warm tone that the hollow bodied guitar had. In response to this, Gibson created the first semi-hollow bodied guitar, the ES355. The semi-hollow, or semi-acoustic, body has a solid centre and the ‘wings’ either side are hollow. It was popular because it had the darker, more pleasing tone of the hollow bodied guitar, but didn’t suffer with feedback issues.

Bass guitar

In the 1930s, Paul Tutmarc deigned the first known electric bass guitar. It was designed to be played horizontally and had frets, which were both pretty radical at the time, due to the widespread use of the upright, fretless bass. It was solid-bodied and had a single pickup. Only 100 or so were made, so the electric bass wasn’t a huge commercial success, not until Fender released their precision bass in 1951, which was the first mass-produced electric bass guitar. It was known as the precision bass because it had frets, which the upright bass did not, meaning that the tuning could be more precise. The precision bass is solid-bodied and originally had a single-coil pickup, but in 1957 it was redesigned to have a humbucker pickup instead.

Not a lot has changed about the bass guitar since the invention of the precision bass, and they are still very popular and widely used today. However, in 1955, a slightly different type of electric bass guitar was invented; the Höfner 500/1 violin bass (pictured left). It was hollow-bodied, but had no sound holes like hollow-bodied guitars do, so was also referred to as a semi-hollow body, and it has two humbucker pickups. The success of the bass was mostly down to Paul McCartney using one. He played bass left handed and, due to its symmetrical shape, suited this style of playing very well.

Theremin

The Theremin, invented by Leo Theremin in 1920, is considered to be the first electronic instrument. It consists of two antennas; one to control pitch and one to control volume. The unique thing about this instrument is that you don’t have to touch it as the sound is produced by a radio frequency oscillating circuit, and the sound is changed by disrupting the circuit’s electromagnetic field. The closer your hand is to the pitch antenna, the higher the note is. Louder notes are played by moving your hand further away from the volume antenna.

The pitch circuit (connected to the vertical antenna) uses two oscillators; one is fixed and generates waves at a static frequency, and the other is variable meaning it can generate a range of frequencies. Both the outputs of these oscillators are combined together in the Theremin and this forms the resulting audible musical tone. The volume circuit, connected to the horizontal antenna, controls the output level of the pitch circuit. Much like the pitch circuit, it uses an oscillator, and disrupting the electromagnetic field of this antenna causes the volume to change.

Although you might think it looks easy to play, the Theremin is notoriously difficult to play, and partly due to this fact, the Theremin didn’t sell very well and sold just under 500 original units.

Mellotron

The Mellotron is a keyboard instrument and produces sound through each key triggering the playback of prerecorded tape within the instrument. It was originally designed as a successor to the home organ, but turned out to be more well known as an early example of a sampler. Depending on what model of Mellotron you get, you can switch between different ‘instruments’ or tapes with different recorded sounds on them. On some you could even take the tapes out and put your own samples in there.

They weren’t a huge commercial success due to their price (about £1000, which is a lot in the ’60s when a house was worth about £3000) and their lack of portability; the lightest one made was 55kg and moving the instrument from one room climate to another could cause the tapes to become damaged. They were, however, pretty popular with many bands, particularly psychedelic rock groups, who had the money to buy one and the staff the staff to transport them.

Electric Organ

The electric organ was designed to imitate the sounds of pipe and reed organs. The most common type of electric organ is the tonewheel organ, with the Hammond organ (invented in 1934) being the most popular and well known. This type of organ produces sounds through tonewheels, which are rapidly rotating wheels which excite transducers and, via amplification, produce a range of pitches. The Hammond organ also uses Leslie rotary speakers to create a sense of space in the sound. The electric organ is associated with jazz, gospel and soul music.

Electric Piano

Electric pianos were invented so that they could be heard over other instruments in an ensemble. They work in the same way as a regular piano in that when a key is pressed, this triggers a hammer to hit the corresponding string inside and creates an audible note. However, unlike regular pianos, electric pianos contain pickups, which convert the vibrational energy of the strings into electrical signals which can then be connected to an amplifier.

There are three main types of electric piano, named by the material inside the instrument that is struck by hammers; string, reed and tuning fork. The first electric pianos contained metal strings that were struck. In the 1920s, the first attempts were made to electrify the grand piano, and in 1939 the RCA Storytone was launched and became the first commercially available electric piano.

A prominent example of a reed struck piano is the Wurlitzer, which went into production in 1955. Inside, flat steel reeds are struck by felt hammers and have a vibraphone-like sound. The first tuning-fork struck piano was the Fender Rhodes, which was released in the 1970s, which had either 73 or 88 keys depending on the model. Confusingly, there aren’t actually any tuning forks inside the Fender Rhodes, but a thin metal rod for each key. The vibration of this rod is captured by pickups at the other end of the rod to the hammer and induces an electrical current which powers an amplifier.

Clavinet

A clavinet is an electric clavichord. A clavichord is a keyboard instrument that contains brass or iron strings that are plucked with small metal blades when a key is pressed. A clavinet was introduced in 1964, have 60 keys and, much like the electric piano, have pickups at the end of each string to convert the vibrational energy into electrical energy.