June 2018 – A Potted History of the Guitar Part IV

Without further ado, let’s get stuck into Part IV of the history of the guitar. As the story was left at the end of the last article during the 1920s and early 1930s, something new was needed to ensure that guitars would not only be able to compete with other instruments in a live situation but also become the catalyst for a musical revolution to mirror what was taking place in wider society. Just in case you were lulled into a sense of coherent continuity, this month’s article is a bit different from what has been covered so far.

 

This part is presented as part of a whole. If you wish to recap on previous articles in the ‘Potted History of the Guitar’ series, you can access them here (each part opens in a new browser tab):

 

Please remember that this is written purely for entertainment purposes and is not intended as an academic tome. While I have tried to be diligent in my research, there are undoubtedly improvements that could be made, so corrections and clarifications are genuinely welcomed. This is quite a long article, so I hope you are sitting comfortably.

 

Needing to be heard

The problem for guitarists in the 1920s was a simple but fundamental and frustrating one. The amount of volume that could be attained from purely acoustic guitar designs had got as far as it was likely to get at the start of the 1930s. Guitarists were still struggling to be heard in noisy live music environments as part of jazz, swing, big band and dance orchestras. Despite the strengths of steel strung folk guitars, archtop guitars and resonator guitars, the lack of volume continued to be a problem for guitarists throughout the early part of the 20th Century. A number of clever innovations attempted to help acoustic guitarists cut through the mix but they didn’t really capture mainstream attention and passed into obscurity, leaving demanding musicians still yearning for louder instruments.

1920s New Orleans Jazz Swing Band

 

Creative inventors, engineers and entrepreneurs were determined to find a workable solution. Perhaps the biggest game‑changing watershed in the entire history of guitar building was about to take place in America in the 1930s. The transformation depended on coincidental and mutually dependent developments; the magnetic pickup, the portable valve amplifier and its associated loudspeaker(s). Undoubtedly, the amplifier came first, simply because it could be driven by other inputs, such as early microphones, while the pickup followed to take advantage of the opportunity. Logic suggests that the converse would make little sense, as a pickup without some means of manipulating the signal s essentially redundant.

 

By the end of the 19th Century, early microphones were being used in telephone, broadcasting and recording industries. In 1916, the first condenser microphone was invented and in 1923, the first moving coil and ribbon microphones were developed. Given the timing, it seemed logical to experiment with microphones to capture the sound from acoustic guitars. However, the results weren’t particularly successful and the microphone proved to be a dead end for guitarists at the time. A more practical and reliable alternative was required to capture the physical energy produced by a stringed instrument and convert it into a usable electrical signal that could then be amplified and output.

 

Before starting to look at the early electric instruments that changed modern guitar music forever, it is worth taking a temporary detour to look at the catalysts that led to the step change. Once the technical inhibitors had been overcome and the various elements combined, electric guitars became a realistic and achievable proposition.

 

The electro magnetic guitar pickup

By the 1920s and 1930s, the science of using magnetism and wire coils to induce an electric current had been understood for several decades. It would, however, take some ingenuity to apply the various scientific principles involved to overcome the specific practical problems experienced by guitarists of the time. Within this context, we need to go right back to basics as a starting point.

 

An electromagnetic guitar pickup is basically a passive transducer that uses Faraday’s law of induction, named after English scientist Michael Faraday (1791‑1867), to produce an electromagnetic force. The physical movement of the vibrating steel string of a strummed or plucked guitar disturbs the magnetic field and induces a small voltage of between 100mV and 1V through the coil. This differs from a simple microphone, which works by converting pressure variations in the air (sound waves), into the mechanical motion of a diaphragm, which in turn produces an electrical signal (depending on the type of technology used).

Electromagnetic Pickup Principle

 

A simple electromagnetic guitar pickup is generally constructed from one or more permanent magnets, wrapped many thousands of times in a coil made of fine copper wire. Most early guitar pickups comprised only one magnet and coil, hereafter referred to as single coil pickups. The weak electrical signal is then passed down an electrical lead to a separate amplifier where the signal is multiplied many times to drive a passive loudspeaker that reproduces the original signal at greater volume.

 

Unlike a microphone, the electromagnetic pickup does not reproduce the actual acoustic sound waves emanating from the guitar. The natural resonance of the instrument may cause the strings to vibrate in a certain way and this variation is picked up by the transducer, which may explain the differences in sound between two instruments using the same pickup, electrics, amplifier and speakers. As a result, at least in the early days, the characteristics of the pickup combined with the rest of the signal chain probably had more to do with the sound that audiences heard, rather than that of the actual instrument itself. There are innumerable permutations in which the basic components of magnets and wire can be configured to produce different outputs and over the years, pickup designers have used these variations to differentiate their pickups from those produced by others.

 

Gibson employee, Lloyd Loar had experimented with stringed instrument pickups as early as 1924, shortly before he left the company. Loar attempted to produce an electrical signal from vibrations passed from the strings through the bridge to the magnet and coil. Loar’s work did not lead to a successful product and guitarists had to wait a while longer.

 

American inventor and musician, George Beauchamp, who had been involved with the National String Instrument Corporation and the development of their resonator guitars, was also involved with another resourceful enterprise at the beginning of the 1930s. He teamed up with Adolph Rickenbacher to form the company was originally called Ro Pat In Corporation, which later became Electro String Instrument Corporation and later still, Rickenbacker, a name that most guitarists will recognise. Ro-Pat-In was instrumental in taking a fundamental new approach to electric guitar design.

Rickenbacker Early Logo

 

Through Electro String, Beauchamp filed a patent in June 1934 setting out his pickup design as part of a complete ‘Electrical Stringed Musical Instrument’. Beauchamp’s ‘horsehoe’ pickup design comprised two ‘U’‑shaped magnets encircling the strings. Beauchamp’s application was granted by the U.S. Patent Office in August 1937. The patent was important because it was for a solid body electric guitar using a magnetic pickup, not just the pickup on its own – the development of the instrument will be covered in the next part of the story so, for now, the focus is solely on the pickup.

Rickenbacker Electric Guitar Patent (1937 Detail)

 

Ironically, in February 1936, Guy Hart filed a patent on behalf of Gibson for an ‘Electric Musical Instrument’ and this was awarded by the Patent office in July 1937, just 28 days before Beauchamp’s earlier patent application was confirmed.

Guy Hart Gibson Pickup Patent (1937)

 

Although unknown at the time, another single coil guitar pickup patent was filed in September 1944 by American inventor and entrepreneur Leo Fender. That application was for a ‘pickup unit for instruments’, which was awarded in December 1948. Although not as historically significant as other pickup patents, it was a clear indication of the direction that Leo Fender was heading prior to founding the company that would bear his name.

Fender Pickup Patent (1944)

 

Another important principle of basic physics caused a significant problem for early pickup designers, and it still does even today. In addition to the desirable characteristic of electrical induction for guitar pickups, electromagnetic coils also act as directional antennae. As far as musical instruments go, this unwanted ‘feature’ means that single coil pickups not only pick up string vibrations but they also pick up interference from alternating mains current used by electrical appliances. Depending on position of the pickup in relation to other electrical equipment, of which there are usually many in a live music venue, the interference manifests itself as a continuous and insistent hum, which is then in turn amplified by a guitar amplifier.

Mains Hum

 

One ingenious solution to the problem of mains‑induced hum was to invent a guitar pickup that still produced a signal from string vibrations while eradicating the interference from nearby electrical equipment. The clever answer was the invention of the ‘humbucking’ pickup, which uses two magnets, each with a coil of wire wound in opposite directions. Electrically induced mains interference affects both coils equally and, because each one is wound in opposing directions, the interference is cancelled out, thereby eradicating (or ‘bucking’) the hum. More importantly, not only do the coils still induce a voltage, they output a stronger signal because there are two coils instead of one. As the problem is all but removed at source, there is no hum to be amplified.

Single Coil & Humbucker Pickup Construction

 

Arguments persist as to who invented the humbucking guitar pickup. Many commentators give the accolade to Seth Lover (1910‑1997), who was an electronics designer working for Gibson at the time and filed a patent in June 1955. Lover’s closest competitor in the race to be recognised for the humbucking pickup came from Joseph Butts, who later worked for Gretsch. Butts filed another humbucking pickup patent some 18 months later in January 1957. It was Butts’ application that was awarded first in June 1959, while Lover’s patent was awarded in July 1959. As far as many working musicians were concerned, the invention was successful and that was all that mattered.

Seth Lover
Seth Lover Humbucker Patent (1959)
Joseph Butts Humbucker Patent (1959)

 

Generally speaking (but not always, especially if obscured by a cover), it is relatively easy to spot the difference between slim single coil pickups and their larger dual‑coil humbucking counterparts. The latter normally have two coil bobbins traditionally mounted side‑by‑side. Within these two broad types, there are many, many different makes and styles of pickup to suit most needs.

Single Coil & Humbucker Pickup Types

 

Hum is not the only affliction that electric guitar builders have to deal with. All electromagnetic pickups, even those produced today, are prone to audio feedback, which is often heard as an undesirable high pitched shriek or howl. Feedback is a phenomenon called the Larsen Effect after the Danish scientist Søren Absalon Larsen (1871-1957) who discovered it. Audio feedback is caused by a sound loop that exists between an audio input such as a pickup or microphone and an audio output such as an loudspeaker fed by an amplifier. The electrical signal from the input is amplified through a loudspeaker and is then picked up again by the input and so on, continuously. The sound of the feedback is shaped by the resonant frequencies and proximity of the various components in the loop, including room acoustics. Most of the time, feedback is considered problematic and often unpredictable. However many guitarists have learned to harness and control feedback in a positive musical way to create additional sounds.

Audio Feedback Loop

 

Some contemporary pickup manufacturers go to great lengths to replicate the authentic tonal characteristics of vintage pickups. One of those widely imitated pickups is also probably the most famous of humbucking pickups. Used on Gibson guitars from the late 1950s, the PAF (Patent Applied For), named after the black sticker on the baseplate, has come to define Gibson’s sound for many guitarists. The PAFs are particularly revered, as they were used in sunburst Gibson Les Paul Standards from 1958‑1960, often regarded as the ‘golden years’ for Gibson.

1959 Gibson PAF Pickups Front
1959 Gibson PAF Pickup Baseplate

 

Today, many independent pickup builders not only pay homage to vintage designs but also strive to create their own distinctive reputation. Third party pickup builders may make OEM (Original Equipment Manufacturer) and aftermarket pickups in a huge range of types. Such companies include Seymour Duncan, Di Marzio, EMG, Lollar and Bare Knuckle, among many others. Pickup choice in the 21st Century is very much down to personal preference and the options are nigh on infinite – very different from the 1930s.

Guitar Pickup Types

 

The sounds generated by single coil and humbucking pickups are noticeably different. Not only do single coil pickups tend to produce a weaker signal, they sound thinner and cleaner, while more powerful humbucking pickups tend to sound fatter and warmer. Guitarists noticed this variation and took advantage of the differences to shape their own playing style and develop their distinctive tone. In addition, humbuckers are often considered better suited to overdriving pre‑amplifiers, thereby adding some controllable, distinctive and desirable harmonic distortion, making them popular in higher gain rock music.

 

By the 1950s manufacturers were commonly using two or more pickups on a guitar for added tonal versatility, initially adding a second or third pickup of the same type, for instance commonly used configurations include 2 humbuckers (e.g. Gibson Les Paul) or 3 single coils (e.g. Fender Stratocaster). Many guitar makers today mix different types of pickups on one guitar to broaden the range of sounds available.

Common Pickup Configurations

 

Some pickup arrangements also allow pickups to be engaged in series or parallel or in/out of phase to give musicians a greater number of tonal options. Since the 1970s, pickup designers have enabled the signal from the two coils of a humbucking pickup to be ‘split’ (NB. not ‘tapped’). By using a switch, guitarists may enable a split humbucker to sound either like a traditional humbucker or to emulate the distinctive sound of a single coil pickup. All these various techniques provide guitarists with greater flexibility from their pickup(s).

 

Simplistically, guitar pickups may also be described either as passive or active. Passive pickups are the basic devices that have been described so far, while active pickups incorporate some form of electronic circuitry in the guitar to modify the signal, normally powered by an on‑board battery. Outwardly, there is often little to distinguish whether pickups are active or not. Putting active electronics into a guitar has been around since at least the 1960s and can range from a simple pre‑amp to boost the pickup signal to elaborate on‑board effects or even low powered amplification.

EMG 81 & 85 Active Pickups

 

Since its inception 1930s, the humble guitar pickup has been adapted into many diverse forms. The majority of pickups in the early 21st Century remain passive single coil or humbucking types. However, there have been other pickup innovations along the way diverging from the norm. These alternative technologies include, amongst many other pickup types; hexaphonic (that feed individual string signals to MIDI/synthesizer controllers), piezoelectric (using crystals to induce current), microphonic (converting sound wave vibrations to electricity), electrostatic (using a capacitor to vary electrical capacitance), optical (interrupting a beam of light detected by a sensor), etc.

 

The understanding of the science behind pickup materials and dynamics between the components has been improved and refined significantly since the 1930s. However, the basic principles behind the passive transducing electromagnetic pickup remain pertinent today and are likely to remain so for the foreseeable future. Magnetic pickups are, by far, the most common type used by electric guitars in the late 20th and early 21st Centuries. This may be about to change.

 

With the digital revolution, there are numerous innovations occurring today that will lead to radical new pickup designs in the future. Future musicians can expect many new ways of converting the vibrations from humble plucked guitar strings into electrical signals that can be manipulated in ways we cannot yet contemplate. The possibly unstoppable migration from analogue to digital technology will continue. We can only speculate as to how far digital processes will encroach into the hitherto staunchly analogue domain of the guitar. Already, we have seen digital devices that enable the output from a guitar’ pickup to ‘model’ other types of guitar and even other instruments by modifying the signal digitally. We have also seen guitars as being a source trigger for external synthesis and various guitar synths have been around since the 1970s. It seems somewhat ironic that the digital age is enabling ever more accurate simulations of the earliest analogue pickups including the original’s crude and accidental inconsistencies.

 

While this section of the story is about guitar pickups, it is worth remembering that pickups have also been used successfully on many other types of stringed instrument.

 

Once the concept had been proven, the next step was to apply actual real‑world pickups in a practical way. There were essentially two methods of implementing an electromagnetic pickup for use on a guitar. One way was to add a pickup to existing acoustic instruments and the other was to invent an entirely new type of guitar with the pickup as an integral part of the design. How these two approaches came about will be covered in the next part of the story.

 

The pickup on its own, however, is of little use in isolation. Another crucial part of the equation was to take the weak signal from the guitar’s pickup and manipulate it electronically to make it much louder, which is where a completely different solution was needed.

 

The electric guitar amplifier

Possibly the major challenge with introducing guitar pickups was to turn the tiny voltage produced by the pickups into a sound that provided practical real‑world volume and tone for working musicians playing in noisy bands on the road.

 

The essential piece of equipment actually comprises two crucial components, the electrical amplifier and one or more loudspeakers. Amplifiers largely fall into two broad categories – either as discrete units comprising the electronics in a ‘head’ unit with loudspeakers installed in a separate cabinet, or with both amplifier and speaker(s) integrated into a single ‘combo’ amp. It is worth looking at the origins of both the electronics and the loudspeaker separately.

 

For travelling musicians from the 1930s on, amps also needed to be portable, so size and weight were particular considerations, as was electrical safety, durability and reliability. In addition, some degree of industry standardisation to enable interchangeability between instruments, electronics and venues was important.

 

The Amplifier

In the early days, amplifying a signal from a pickup was all that a guitar amp was really required to do. Controls were very basic, usually just a single input channel with a volume and, maybe, a tone knob. It would take some time before more flexible electronics were added to these basic amplifier circuits. Nowadays, the diversity of amps ranges from the very simple to the incredibly complex. The latter often including, just for starters, multiple switched channels, gain controls, effects loops, digital modelling alongside advanced EQ, flexible on‑board effects and digital interfaces. However, the fundamental principles of amp utility haven’t really changed that much since amps were first invented in the 1920s and when guitarists started to use them in the 1930s.

Simple Amp Control Panel

 

Put very simply, an amplifier is made up of active electronics that are designed to take an input signal, multiply it many times in strength and output it to a loudspeaker at a volume that is considerably louder than the original input. The electronics of an amplifier comprise essentially two discrete parts, a pre‑amp that controls the incoming signal and shapes it ready to be boosted and output by the power amp section that then drives the loudspeaker(s). It is these two amp sections that determine the overall character and volume of the audio output.

 

Amplifier output is usually measured in watts and provides a crude indication of power output (volts x amps = watts). The relationship between watts and sound pressure levels heard by the human ear is logarithmic. Generalising, it takes ten times the output power in watts to double the perceived audio volume. In addition, it takes considerably more amplifier power to reproduce low-frequency sound, especially at high volume, so bass amps tend to have higher power output ratings.

 

While early amplifiers were configured to the environment in which they were most likely to be put, such as practice, studio or stage amps, many modern amps use various techniques to minimise this artificial distinction, such as master volume controls, power attenuators or circuits used to modify amplifier stages to suit.

 

Up until the 1970s, thermionic valves – also known as vacuum tubes – were a principal electronic component and one that contributed significantly to both the power and sonic character of the amplifier. A valve is a relatively simple device used to control electrical current between its electrodes. The first valve was invented in 1904 by English electric engineer John Ambrose Fleming (1849-1945).

 

At its most basic, a valve comprises an external glass container used to maintain a vacuum is attached to the valve base. Inside the valve there is a heater, an electron‑emitting cathode/filament and an electron‑collecting anode/plate. Electrical current, in the form of negatively charged electrons, flows through the vacuum in one direction only from the cathode to the anode. An electrical grid can be used to control the current and is the one often used for amplification because the grid can be used to vary the number of electrons reaching the anode and, thereby, controls the amount of gain. Valves are often described by the number of electrodes, for instance; diode, triode, tetrode  or pentode valves (2, 3, 4 and 5 respectively). The humble valve has been used in many applications, such as amplification, rectification, switching, oscillation, and display.

Valve Construction

 

Valves come in many shapes and sizes and vary according to the function they are required to perform in the amp stages. Generally speaking, pre-amp tubes tend to be smaller, while power amp valves tend to be larger.

Valve Types

 

There are numerous alternatives and variations of valves and there isn’t room to cover the range of technical differences. Thankfully, there has been a degree of commonality in amplifier design over the decades. Typical valves used in pre‑amps include models such as the 12AX7/ECC83. Typical valves used in power amps include models such as the EL-34, EL-84, KT66/77/88, 6L6/5881 and 5150. Valves impart a characteristic ‘natural’ sonic signature and tend to be sensitive to a guitarist’s playing dynamics, which is why they are still widely favoured by many musicians to this day. While technically outdated and obsolete, there is a notable modern‑day industry built around valve production, amp manufacturing and valve amp maintenance.

Common Valve Types

 

The valve is the technological precursor to modern semiconductors. Semiconductors are often made of silicon, although they can be made from other materials, such as germanium. A transistor is a solid‑state semiconductor that roughly performs the same function as a valve and is commonly used for amplification. Transistors are smaller, cheaper, lighter, run cooler, are more reliable and more resilient than valves. Some manufacturers produce hybrid amps that aim to take the best characteristics of both valve and transistor technologies.

Transistors

 

Taking things even further away from archaic valve technology, electronics using complex digital microprocessors are commonplace. Not only can DSP (Digital Signal Processor) chips produce their own sounds but also they enable a single unit to model a multiplicity of amplifier models that would be impossible using traditional technology. In addition, they can also emulate multiple effects, speaker cabinets, microphone placements, studio interfaces, and so on. Reliable and robust digital processing amps able to be used equally well at home, in the studio and on stage are once again attempting to usurp territory previously held by archaic analogue amps.

Digital DSP Microprocessor

 

Specialist amps are made to make the most of other, albeit similar, electric instruments. For instance, electro‑acoustic guitars (acoustic guitars with pickups) produce a wider frequency range and tend to be ‘cleaner’ sounding than electric guitar amps, which has led to increasingly elaborate amp electronics to cater for the particular needs of acoustic guitar players. Bass amps and speakers are also engineered specifically to provide for the demanding amplification used by bass guitarists. There are no hard and fast rules, the lines are not always clearly drawn and there is inevitably some interchangeability between the general types.

 

One of the keys to success is to match the characteristics of the amplifier stages to the loudspeakers, so it is worth looking next at the humble loudspeaker and the important part it plays in the guitar sound’s signal chain.

 

The Loudspeaker

The latter part of the 19th Century was ripe for invention in the field of sound reproduction. As with other sections, only a few of the key milestones can be covered here. Prior to the invention of the modern loudspeaker, megaphones and bulky ‘radio horns’ had been used to increase acoustic volume. However these proved impractical because of their size and weight, limited frequency range and low sound pressure levels.

Early PA System

 

German teacher, Johann Philipp Reis was, perhaps, the first to develop a rudimentary type of experimental electric loudspeaker in 1861. Alexander Graham Bell was the first to patent his loudspeaker design in 1876 for use in his telephone, shortly followed by Ernst W. Siemens who patented his ‘magneto-electric apparatus’ in 1874. Thomas Edison and Nikola Tesla were also experimenting with sound around the same time. By 1898, Horace Short was working with compressed air drivers and Oliver Lodge was developing a ‘dynamic’ speaker using magnets and moving coils with horns to amplify sound. Danish‑American engineer Peter L. Jensen (1886-1961) is often cited as co‑inventor of moving coil speakers in 1915 and he started applying the technology for use in real world situations. Jensen founded his company, Magnavox, in 1915 to market products for telephones and public address (PA) systems. Magnavox is now part of the massive Philips corporation.

 

Things changed considerably in the 1920s with the introduction of the first amplified moving coil loudspeaker using a conical paper speaker diaphragm, which was invented in 1925 by Edward W. Kellogg and Chester W. Rice, both of whom worked for General Electric in New York, USA. Their research was important as it established both the principle of the amplifier to boost a signal and a speaker able to reproduce a wide and uniform frequency range. Rice filed a patent for the electrodynamic direct radiating ‘loud speaker’ in 1925, which was awarded in April 1929. Their speaker was introduced to the market under RCA’s Radiola brand in 1926.

Kellogg & Rice (1925)
Kellogg & Rice Patent (1925)
1920s Speaker (Kellogg & Rice)

 

Early speakers used powered electromagnets, as permanent magnets were scarce at the time, although Jensen released a fixed magnet speaker in 1930. Lightweight Alnico alloy magnets became available after WWII, making the technology more accessible enabling further innovations to take place. Other inventions along the way included, for example, 2‑way systems using a crossover to separate frequency bands (1937) and coaxial speakers (1943). Once the concept of the moving coil speaker had been proven in practical applications, it has become the de facto standard within the music industry for nearly a century.

 

The loudspeaker, as we know it today, is essentially a mechanical electroacoustic transducer that serves the opposite function to a microphone in that it converts an electrical signal into sound waves. A traditional moving coil speaker is passive in that it relies on an already amplified signal being fed to it and it doesn’t require its own power supply. The incoming amplified signal is fed into a coil of wire, known as the voice coil, suspended between the poles of a permanent magnet. The voice coil is attached to the apex of a conical diaphragm known as a speaker cone, originally made of paper. The outer edge of the cone is mounted within a fixed metal chassis, usually within a cabinet. The electrical signal makes the voice coil move back and forth rapidly within the magnet thereby pushing on the cone to produce sound waves. The more air that the moving speaker cone displaces, the louder the perceived sound is. Different sizes and types of speaker are used to deliver different sound frequency ranges. Generally, larger speakers are used to deliver lower bass frequencies and smaller ones used for higher treble frequencies.

Moving Coil Dynamic Speaker

 

Loudspeakers are usually attached to a flat panel (baffle) with circular holes cut into it such that the sound waves produced by the speaker cones can escape directly into the listening environment. The baffle with its speaker(s) is normally mounted inside either an open‑back or closed‑back wooden cabinet.

 

Like amplifier outputs, speaker output is usually measured in watts, which is the electrical power needed to drive the speaker. More watts generally, although not always, indicates greater volume. Like all electrical devices, a speaker provides some opposition to the signal being fed into it, called impedance, measured in ohms. Some speakers are ‘hard to drive’ and have a low impedance, which means that it requires greater current from the amplifier to result in the same output level than a high impedance speaker. As a result, it is important to match a speaker’s characteristics to the amp that is driving it.

 

Most loudspeakers, even those produced today, are relatively inefficient devices with only about 1% of the electrical energy being converted into acoustic energy. Most of the remaining energy is converted into heat. The sensitivity of the speaker describes how much relative electrical energy is converted into sound pressure level, measured in decibels.

 

The other important factor for loudspeaker performance is its frequency response. Human hearing generally covers the range 20-20,000 Hertz (cycles per second). People’s sensitivity to frequencies is not uniform and it varies depending on pitch. Human hearing is usually most sensitive in the 2,000-4,000 Hertz range.

 

Famous names in the field of loudspeaker manufacturing today include Celestion, Jensen, Weber, Electro Voice, JBL, Bose, Fane, Altec Lansing, Mackie, and Peavey amongst many others.

 

Celestion Speakers

 

Despite its many drawbacks, the moving coil loudspeaker was (and generally still is) the most effective mechanism for the job and they remain in very wide use today. Speakers come in a multiplicity of shapes and sizes and are used in so many different ways. However, like the pickup and amplifier, the basic principles of speaker design can be traced back to the early part of the 20th Century.

 

Guitar Amps

Initially, bulky battery‑powered valve amps and speakers were used in PA systems and in movie theatres of the time. Because of their bulk and relative fragility, these early systems tended to be fixed installations. From c.1927, portable AC mains‑powered amps became available and musicians started to adopt the technology.

 

In 1928, Stromberg‑Voisinet advertised the first electric instrument and amplifier package. However, it was not a commercial success and no verified examples exist today. In 1929, Vega introduced a portable amplifier to be used with banjos.

Stromberg-Voisinet CMI Catalogue (1929)

 

It wasn’t until 1932 when the Electro String Instrument Corporation – later to become Rickenbacker – was formed to bring the electric guitar to market that things really took off. Electro launched a ‘high output’ guitar amp to accompany their new solid body electric lap steel guitars, as Hawaiian music was highly popular at the time across America. The first commercial solid bodied electric guitar and amplifier made by Electro String essentially established the format for early combo amps comprising an electronic amplifier mounted inside a wooden cabinet along with a speaker. The new combo amp also had a carrying handle to make it portable and, shortly after, the company added metal corners to protect the cabinets in transit.

1930s Electro Combo Amp

 

In 1933, Dobro introduced the first guitar amp combo with twin 8 inch speakers. By around 1935, the demand for amplified electric guitars became unstoppable and the electric guitar music revolution had begun. Other companies such as National, RCA Victor, Audio-Vox, Vivi‑Tone, Premier, Vega, Kay, Valco and Volu‑Tone, promoted their own amps to musicians, with varying degrees of success during the 1930s and 1940s. Gibson was also experimenting with amplifiers in the early 1930s although none were made commercially available at the time. Most of the early valve amplifiers were low powered by today’s standards, usually less than 10-15 watts and using small speakers, often of 10 inches or less in diameter.

c.1935 National Dobro Guitar Amp

 

In 1938, American electronics technician, Clarence Leonidas ‘Leo’ Fender (1909-1991) established Fender Radio Service to repair a wide variety of electronic equipment. He found that musicians would come to him for PA and amplifier repairs and rentals. Seeing the potential of the music industry and started to focus more on musical equipment manufacture. Fender began a short‑lived venture in 1944 with Clayton ‘Doc’ Kauffman, a former employee of Rickenbacker called K&F Manufacturing Corporation with the intention to build Hawaiian lap steel guitars and amplifiers.

Leo Fender

 

In 1946, after Kauffman and Fender parted company, Leo founded the company with which he will forever be associated, Fender Electric Instrument Manufacturing Company, based in Fullerton, California. Shortly thereafter, they introduced the first guitar amps carrying the Fender name. Early Fender combo amplifiers included the Fender Princeton (1947-1979) and Champion 800 (1948-1982).

1948 Fender Princeton & Champion 800

 

In 1952, shortly after Fender introduced their Broadcaster guitar which would become the legendary Telecaster, the company introduced what would be, perhaps, its most celebrated combo amp, the famous Fender Twin. The Twin moniker derived from its dual 12 inch speakers. The Twin has been released in many versions over its long history, with its power output ranging from its original 25 watts to a high of 135 watts in the late 1970s. The perennial Fender Twin remains in production today and has become an industry standard.

1955 Fender Twin Amp

 

Meanwhile, based in Kent, England Tom Jennings (1918-1978) founded British company Vox in 1947 to produce musical equipment. It wasn’t until 1958 that Vox released its first guitar amp, the 15‑watt AC15. A year later, at the request of The Shadows’ guitarist Hank Marvin, Vox introduced its most famous model, the AC30, intended to compete with America’s powerful Fender Twin amp. The AC30 proved to be a very successful product and in updated form, it remains in production today.

1950s Vox AC30-4

 

It wasn’t until the 1950s that mass produced guitar amplifiers really became commonplace and incorporated many of the features now expected from an amp including, for instance, multiple tone controls, tremolo and reverb.

 

In addition, contemporary popular music of the time was developing rapidly and guitarists began to experiment by overdriving their amplifiers to distort the guitar’s sound at much higher volumes. From the mid‑1960s guitarists sought to control the level of overdrive and distortion (also known as clipping) as a creative tool. One particular characteristic of natural valve distortion is that clipping also tends to compress the signal as the volume is increased, meaning the output tends to sound ‘thicker’, rather than louder, emphasising the guitar’s sustain.

Distortion

 

Guitarist Dave Davies of English band The Kinks is often credited with popularising guitar distortion. On one occasion, Davies himself admitted to slashing the speaker cone of his Elpico AC55 ‘little green amp’ with a razor blade out of frustration and in the process of doing so, he made it sound distorted and nasty. The Kinks’ song, ‘You Really Got Me’ (1964) is often cited, rightly or wrongly, as the first hit record featuring heavy guitar distortion (using a Vox AC30).

Dave Davies (The Kinks) 1967
Elpico AC55 ‘Little Green Amp’ c1956

 

The search for new guitar sounds in the 1960s helped to ignite the drive for compact guitar effect pedals, initially with simple fuzz and wah effects. A whole industry developed during the late 1960s and 1970s including brands such as Electro‑Harmonix, MXR, Maestro, Boss and Ibanez, amongst many, many others. Effects have ever since been used to complement guitars and amps as an integral part of a musician’s signal chain. The market for effect pedals has grown into a massive industry in its own right.

 

Early Effect Pedals

 

The development of guitars, amps and popular musical styles of the 1950s defined the template on which succeeding generations of guitarists would build incrementally. Many modern amps and amplifier innovations hark back to the best examples of this ‘golden’ period. Driven by the success of the 1950s, particularly the popularity of Fender amps, the quest for more volume seemed unquenchable. The first 100 watt amps were made by Leo Fender for surf guitarist Dick Dale, while Jim Marshall of legendary British amplifier manufacturers Marshall did the same for Pete Townshend and John Entwistle of rock band The Who.  Dr. Jim Marshall OBE was affectionately nicknamed, ‘the father of loud’.

Dr Jim Marshall OBE

 

High power, high gain valve guitar amps became the norm at the end of the 1960s and into the 1970s. It was not uncommon to see large stages filled with gargantuan ‘stacks’ of loudspeaker cabinets powered by banks of high powered amps. Marshall is the brand most associated with the classic guitar stack, which at its simplest comprises a 50 or 100 watt amp on top of two 4×12” closed back speaker cabinets, thanks again to Pete Townshend of The Who as well as the likes of Jimi Hendrix and Eric Clapton. The guitar stack has since become inextricably linked with hard, heavy and metal rock music. Music and its essential components very much reflected the cultural and social changes of the times.

Marshall Stacks

 

There have been several technological challenges to the humble valve. A concerted trend away from vacuum tubes towards solid state transistor amps occurred in the 1970s, led by companies like Roland, Peavey and H/H. Other manufacturers adopted a best‑of‑both‑worlds approach by making hybrid solid state/valve amps, led by Leo Fender during his time with Music Man.

Roland JC-120

 

Arguably, Fender, Marshall remain the two predominant and recognisable amplifier brands and, respectively, have come to define the ‘American sound’ and ‘British sound’ respectively. Notably, unlike Fender, Gibson has never had much commercial success with building guitar amps, despite producing some credible models along the way. There are now a myriad of other amplifier manufacturers including famous brand names such as Mesa Boogie, Peavey, Ampeg, Randall, Rivera, Bogner, PRS and Supro in America, and Vox, Orange, Blackstar, Victory, Hi-Watt and Laney in the UK. Outside the USA and UK, there are many successful brands including Hughes & Kettner, Engl, Line6, Roland, Yamaha, BOSS, etc. In order to keep production costs down, many budget models are now produced in the Far East, while the majority of small boutique amp builders cater for the high‑end, being manufactured in limited numbers in America and Europe.

1970s Mesa Boogie Amps

 

Many other famous brand names have passed into history, such as Traynor, Sunn, Multivox Premier, Univox, WEM/Watkins, Sound City, H/H, Selmer, Cornford and Carlsbro although, to be fair, some of these continue to operate in some form or other and may well be rejuvenated at some point. There are far too many brands, past and present, to mention here.

 

Ironically, there is increasing interest in capturing the retro sound and looks of the earliest guitar amplifiers. Many companies are now recreating classic analogue models of the past, often incorporating modern adaptations for reliability, safety and convenience to meet the demands of today’s guitarists. There are many boutique amp builders looking to take the best of old and new and present something different from the current mainstream manufacturers.

 

At this point, no article focusing on guitar amps would be complete without mentioning Dumble amplifiers. Dumble amps are made in very small numbers by Alexander ‘Howard’ Dumble in L.A., California, often by request of well‑heeled professional musicians. The Dumble Overdrive Special is widely regarded as the zenith of limited production boutique amps and, as a result of their quality and rarity, new or used examples have gained almost mythical status and demand extremely high values on the open market.

Dumble Overdrive Special

 

Despite the remarkable sustained popularity of valves, digital modelling technology is now making major inroads into the tube’s traditional territory. As the technological advances behind digital modelling processors that began with the iconic Line 6 Pod through to ever‑improving digital advances from companies like Fractal and Kemper. The audible difference between the ‘antiquated’ originals and modern digital recreations is rapidly diminishing to the point where professional musicians see a competitive advantage in moving to a digital platform.

Kemper Profiler

 

Despite stiff competition from solid state and digital circuits, the valve guitar amp currently remains the de facto standard for many discerning professional guitarists, despite the decidedly old-world technology involved. It will be interesting to see how long genuine valve amplifiers will continue to prosper in the face of the digital revolution. Only time and hindsight will tell. It is likely that valve, analogue solid state and digital technologies will be able to coexist for many years yet.

 

Get connected

Guitars need to be connected to an amp in order to work, often with effect pedals in between. Before wireless and/or digital technology takes over completely, the venerable guitar lead has been the necessary link between input and output since the 1930s. At each end of a traditional interconnecting lead is a remarkable piece of analogue kit that most guitarists rarely think about but cannot live without. Similarly, guitars, amps and effects also have the other part of the same connection.

Jack Plug & Socket

 

The essential connector in question is the ¼“ (6.35 mm) jack plug and its associated socket, which originally dates from c.1878. The first jack connector was invented by George W. Coy and was used for the first commercial manual switchboard at the telephone exchange in New Haven, Connecticut, USA. It is astonishing that, after nearly 1½ centuries, this enduring piece of industry standard equipment is still in ubiquitous use today, long after it became obsolete in telephone systems.

Telephone Exchange – New Haven Connecticut

 

End of Part IV

This has been a self‑contained article that departs from the usual topic of guitars per se. While it might seem a lengthy, in‑depth examination, it only just scratches the surface. As I don’t have the space, knowledge or resources to write comprehensively on the subject, I highly recommend that readers wanting to delve into the historical detail take a look at the innumerable resources available on the ever‑present hinterwebby thing. NB. Credit to all original photographers for images used from Google Images.

 

Arguably, without the complementary inventions of the electromagnetic pickup, the dedicated valve amplifier and the moving coil loudspeaker, the revolution in guitar technology that started in the 1930s and which really took off in the 1950s would not have been possible. It is notable that the scientific principles underpinning today’s electric guitars are still relevant nearly a century later. It is, at least to me, remarkable that, technically, we haven’t really evolved a great deal over the intervening decades. Advances have been incremental refinements, rather than ground breaking. Digital technology may change all that. Watch this space.

 

At long last, in Part V, the story will finally unleash the breakthroughs that led directly to the early electric archtop and solid body guitars. The next revolution in guitar music making was about to happen. Who could possibly have anticipated the impact that the congruence of the three seemingly innocuous bits of music technology covered above would have when brought together.

 

I hope you have enjoyed the journey thus far and thank you for reading. I also hope that you’ll come back and join me on the next part of the guitar’s long journey to the current day. Time to get some vintage gear out and plug in. Until next time…

 

CRAVE Guitars ‘Quote of the Month’: “Excess in any form does not indicate wisdom; rather it evidences the lack of it”

 

© 2018 CRAVE Guitars – Love Vintage Guitars.

 

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