Overcoming Limitations

But the use of PA systems in live musical performances was often limited to simply amplifying the voice so it could be heard above the band. This limitation may have been in part due to the relatively small valve (tube) amplifiers of that era.

To work properly, valves consume large amounts of power and generate a lot of heat so if you put a lot of them together, in order to get greater amplification, the power demands soon become excessive and there’s a risk of the amplifier overheating. Therefore, valve amplifiers of this period were typically limited to around 20 watts of output power.

In the post World War II years, competition was fierce to develop a more efficient method of amplification. Most of the research was conducted by the telephone companies in the hope of cracking the problem of signal loss over long distance telephone lines. Advances in semiconductor technology seemed to point the way, but it was a team of three at Bell Laboratories that made true progress.

John Bardeen, Walter Brattain and William Shockley took a strip of gold foil, sliced it in two with a razor blade, then attached it to a wedge of plastic with paperclips and pushed it up against a chunk of germanium. A small current applied to the germanium changed its conducting properties to allow a larger current to pass between the two pieces of gold foil, thus producing a power gain – and the transistor was born.

Eventually germanium was replaced with silicon, the design was refined, Nobel prizes were awarded and Shockley went on to found Silicon Valley. The great thing about transistors, from an audio point of view, is that they’re much smaller than valves and don’t generate as much heat as tubes, so smaller and more efficient amplifiers could be built.

Devil Music

Improvement and refinement of PA technology continued, with systems for motion pictures being a primary driver. Things really started to get interesting during the 1950s as the invention of the electric guitar and the growing popularity of rock ‘n’ roll increased the need for greater amplification.

Bands were forced to push the limited PAs of the time into distortion to match the energy levels of their performance, resulting in a suitably raucous sound. This caused certain leading manufacturers to declare their warranties void if their systems were operated at full power and some even threatened to cut off retailers who sold their systems to bands who played “the music of the devil.”

Going into the 1960s, bands started carrying their own PA. Often on multi-act bills, the loudspeaker sets were stacked one in front of the next and then removed as its respective owners finished its set. The result was that each act sounded quite different – typically the sound improved as you got to the headline act because they could afford a more expensive PA.

A watershed moment came in August 1965 when the Beatles played Shea Stadium in New York. The exponentially growing popularity of the beat combo from Liverpool meant that they could play somewhere as large as a baseball stadium for the first time.

On paper it made sense; however, the sound systems of the time simply weren’t up to the task. Extra amplifiers and loudspeakers were brought in, and despite the stage being in the middle of the field with the audience in the bleachers, the screaming of the crowd was so loud that they couldn’t hear the band – and the band couldn’t hear themselves.

It’s no coincidence that, just one year later, the band announced their retirement from live performance altogether and subsequently released “Sgt Pepper’s Lonely Hearts Club Band,” a concept album based around a fictional band that they believed could go out on tour on their behalf (albeit in recorded form). The Shea Stadium concert is widely considered a classic example of an industry that tried to run before it could walk.

You might say that the modern touring and sound industries were born the day after that concert. Things certainly started to pick up pace as bands demanded bigger and better systems, and we began to move inexorably into the golden age of the PA.

That first stadium concert, featuring the Beatles at Shea Stadium in Queens, showed that while there was the demand for bands to play large shows, the sound reinforcement systems of the time were simply not up to the task. Most bands carried their own small self-operated systems, which were little more than glorified vocal amplifiers.

Clair & Watkins

Thankfully there were pioneering individuals on both sides of the Atlantic willing to up the ante and usher in the era of the large PA. Notable pioneers included Charlie Watkins of WEM (Watkins Electric Music) in London and Clair Brothers in Lititz, PA.

Gene and Roy Clair received their first system as a Christmas present from their grocer father in 1954, and for the next few years they hired it out to local dances and events. In 1963 they purchased a loudspeaker re-coning business that gave them access to the latest developments and led to them providing the sound system for regular headline acts at the 4,000-capacity Franklin & Marshall College in Lancaster, PA.

In 1966 the brothers impressed Frankie Valli enough for him to hire them to go out on tour, thus forming one of the first touring PA hire companies. What made Clair stand out from the competition was a knack for piecing together the right bits of equipment to provide the loudest and clearest output. It led to the company working with Iron Butterfly, Jefferson Airplane and Cream – for whom they did a prestigious gig at the Spectrum in Philadelphia for an audience of 18,000 in 1968.

Meanwhile over in the U.K., Watkins unveiled his “Slave” PA system at a festival in Windsor in 1967, so called because one amp is the slave that feeds into another to increase the output of the second. Using 10 amplifiers that generated 1,000 watts of power to 20 loudspeakers, the system was able to produce a volume level that saw it’s creator in court for a breach of the peace – thankfully the case was dismissed.

In 1968 WEM introduced the Audiomaster mixer and it instantly became a classic, even though it only offered 5 channels (each channel had controls for volume, bass, mid, treble and a spring reverb).

More importantly, the development of the mixer encouraged the move away from passive mixing (i.e., “set and forget” type operation) and paved the way for a generation of roadies to be elevated to the position of live sound engineer.

A Revelation

However, due to the use of high-impedance microphones, signal loss was a major issue so cable runs were kept to a minimum, which meant the mixer was typically located close to the rest of the system. Fortunately in New York at the Fillmore East, Bill Hanley developed the first multi-core “snake” that enabled the mix position to be moved away from the sound system.

This is something we take for granted now but at the time it was a revelation, as Dinky Dawson (Fleetwood Mac’s engineer) noted: “Up to that moment I had never seen any group mixed from anywhere other than the side of the stage. This was revolutionary!”

Hanley and technical engineer John Chester came up with the idea that placing transformers at the ends of a cable run would facilitate the ability to send high-impedance microphone signals down a balanced line over greater distances without picking up any interference or losing level.

At the time this approach was too large to take on tour, but the development of low-impedance mics that had a built-in balancing transformer, such as the Shure Unidyne III (1965), SM57 (1965) and SM58 (1966), allowed multi-core snakes to become portable.

Shortly thereafter, Dawson became one of the first touring engineers to set up shop in the new “front of house” (FOH) position, located centrally amidst the audience.

The next key step was the development of bigger amplifiers. Despite being 20 years since the invention of the transistor, the most reliable large amplifiers of the late 1960s were still vacuum tube designs where a unit providing 50 watts per channel was considered “hefty” and one capable of delivering 100 watts per channel was “industrial.”

Then in 1967, Crown released the solid state (transistor) DC300 amplifier, so named because it utilized a Direct Coupled (DC) design that was capable of delivering 300 watts of power. What was key to the success of the DC300, above and beyond power, clarity and low distortion, was it’s size at 7 inches tall and weight of 45 pounds, less than a quarter the size and weight of an equivalently powered tube amplifier.