The rock-concert revolution

The Beatles’ stadium tours exposed the gap: bands played through announcement systems while crowd noise buried them. Even the dedicated vocal amplifiers that followed, such as Marshall’s PA 100MarshallPA 100 amplifier1965–1967Marshall's 100-watt PA amplifiers grew from the same development as its first 100-watt guitar amplifier, built in 1965 at Pete Townshend's request. The Master P.A. 100 combined six-channel mixing with four EL34 output valves and five ECC83s.Open profile → and Vox’s later SS100, could not cover an arena. Engineers began assembling dedicated rigs from cinema horns such as the Altec A7, JBL drivers, custom cabinets and industrial amplifiers.

Marshall PA 100 amplifiergermanium from Eichwalde, Germany · CC BY 2.0

Amplifier power made those rigs possible. The Crown DC-300ACrownDC-300A amplifierc. 1972The Crown DC300A succeeded the 1967 [[crown-dc300|DC300]]. A 1973 Audio magazine advertisement lists eight output transistors per channel and ratings of 150 W per channel into 8 ohms, 300 W into 4 ohms, or 600 W bridged mono.Open profile →, the McIntosh MC2300McIntoshMC2300 amplifier1971The McIntosh MC-2300 is a high-power solid-state amplifier rated at 300 watts per channel. McIntosh documents that MC-2300s drove the Grateful Dead's Wall of Sound, which debuted at the Cow Palace, San Francisco, on 23 March 1974, and that Jerry Garcia used his own MC-2300 for guitar.Open profile → and the Phase Linear 700 delivered hundreds of watts per channel. That made it practical to drive horn-loaded bass bins like the JBL 4550 and high-power cones such as the Gauss 4583, and to add the JBL 075JBL075 bullet tweeter1950s–1960sThe JBL 075 'Ring Radiator' is a compression driver with a 1-inch phenolic ring diaphragm feeding an annular throat into a solid aluminium horn. JBL's brochure presents it as a high-frequency reinforcement for extended-range drivers such as the [[jbl-d130|D130]], crossed over at 2,500 Hz.Open profile → tweeter on top. At the microphone, the Shure SM58ShureSM58 microphone1966The Shure SM58 uses the Unidyne III cartridge developed by Ernie Seeler, the same capsule as the [[shure-sm57|SM57]], with a ball-shaped wind and pop grille. After weak broadcast sales it was promoted to live-sound engineers in Las Vegas and became a touring staple.Open profile → and SM57ShureSM57 microphone1965The SM57 is a cardioid dynamic microphone built around Shure's Unidyne III capsule, developed by Ernie Seeler and released in 1965 in the new SM series. The capsule descends from Ben Bauer's 1939 [[shure-55-unidyne|Unidyne]], and it is shared with the [[shure-sm58|SM58]].Open profile → gave touring bands rugged cardioid capsules that resisted feedback from louder stages.

Crown DC-300A amplifierBinksternet · CC BY-SA 3.0McIntosh MC2300 amplifierAwgrasso · CC BY-SA 4.0JBL 075 bullet tweeterJacques from Cape Town, South Africa · CC BY 2.0Shure SM58 microphoneIain Fergusson; derivative by Binksternet · CC BY 2.5Shure SM57 microphoneJud McCranie · CC BY-SA 4.0

The mixing desk grew alongside the speakers. Early rigs ran through small portable units such as the tube Altec 1567AAltec LansingAltec 1567A Mixer1958 (in continued front-line service through the 1960s–70s)The Altec 1567A is a compact, three-rackspace, four-mic/one-line input tube mixer built around 12AX7 and 6CG7 tubes, launched in 1958 for broadcast, recording and sound-reinforcement use. Its octal accessory sockets allowed users to configure input impedances and add transformers, and an optional 'XL' cover fitted XLR connectors for portable field use. Several racks of 1567As were used by the audio crew that recorded the Beatles' August 1965 Shea Stadium concert, and the model's durability kept it in active touring and location-recording service through the late 1960s and into the 1970s.Open profile → and the all-in-one Shure Vocal MasterShure Brothers Inc.Shure Vocal Master VA300/VA3011967The Shure Vocal Master combined a six-channel, all-transistor mixer with a 100-watt power amplifier and built-in spring reverb in a single console chassis, driving a pair of dedicated column loudspeakers. Aimed at bands who could not afford custom touring PA, it became the ubiquitous 'bar band' and small-venue vocal system of the late 1960s and early-to-mid 1970s rock circuit. Shure continued to sell and service the VA300 line into the late 1970s, with the surviving factory operating/service manual documenting its six-channel mixer section, anti-feedback switches and reverb controls.Open profile →, each with only a handful of inputs. As bands added microphones for drums, keyboards and horns, sound companies commissioned bespoke desks: the Kelsey/Morris consoles in Britain, Allen & Heath’s quadraphonic MOD1 for Pink Floyd and Clair Brothers’ own folding consoleClair Brothers AudioClair Brothers Folding Consolec.1975In the mid-1970s, Ron Borthwick and Bruce Jackson developed a highly unconventional live mixing console for Clair Brothers Audio, the Lititz, Pennsylvania touring sound company founded by Roy and Gene Clair. The console's control surface folded directly out of its road case, eliminating the need to lift a heavy top panel into place, and it was the first mixing console fitted with plasma bargraph meters capable of showing simultaneous RMS and peak levels, positioned beside the faders for quick reading. Jackson has stated it was also the first live console to include parametric equalization, letting engineers continuously sweep frequency and bandwidth rather than choose from fixed bands. The desk became Clair Brothers' mainstay touring console for major acts well into the 1980s.Open profile →. By the mid-1970s purpose-built touring desks such as the Soundcraft Series 1SoundcraftSoundcraft Series 11974Soundcraft was founded in 1973 by sound engineer Phil Dudderidge (Led Zeppelin's first dedicated live engineer) and designer Graham Blyth, who had previously worked at PA/console builder Kelsey Morris. Their first product, the Series 1, offered 12 or 16 input channels feeding a stereo main bus plus monitor and echo sends, with four-band fixed-frequency EQ per channel, and was the first mixing console sold already built into its own flight case. An optional 19-pair multicore cable with stagebox let touring crews run a complete snake-and-console package, a format that became standard for rock touring PA through the rest of the decade. The upgraded Series 1S followed in 1975.Open profile → and the modular Midas PR-series packed more channels into road cases, and they fed the larger amplifier and loudspeaker systems of the next era.

Altec Lansing Altec 1567A MixerJake Mohan · CC BY 2.0Shure Brothers Inc. Shure Vocal Master VA300/VA301© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentaryClair Brothers Audio Clair Brothers Folding Console© Published by ProSoundWeb; photographer and original rights holder not credited · Copyright retained by the original rights holder; reproduced for identification and historical commentary (fair use). Reuse permission not established.Soundcraft Soundcraft Series 1© Published by ProSoundWeb; photographer and original rights holder not credited · Copyright retained by the original rights holder; reproduced for identification and historical commentary (fair use). Reuse permission not established.

Bill Hanley ran the sound for Bob Dylan’s electric set at the 1965 Newport Folk Festival. At Monterey Pop in 1967, Abe Jacob designed the festival’s sound system, and McCune Sound’s chief engineer Bob Cavin designed its 16-channel console. On 12 May 1967, at Games for May in London’s Queen Elizabeth Hall, Pink Floyd moved sound around a four-channel loudspeaker layout with a joystick controller. The first unit was stolen after the show; the surviving Azimuth Co-ordinator, built around 1969 by Abbey Road engineer Bernard Speight with four rheostats modified to turn through 90 degrees, is in the V&A (S.294-1980) — context for Allen & Heath’s quadraphonic MOD1. Lexicon’s first product, the Delta T-101 of 1971, was a digital audio delay. Two years later three Eventide DDL 1745EventideDDL 1745Used 1973Three units, each capable of 200 ms, time-aligned the delay towers at Summer Jam at Watkins Glen.Open profile → units time-aligned the delay towers at Watkins Glen, turning the delay tower into a standard festival tool. At McCune, John Meyer and Bob Cavin built the JM-3McCune Sound / John MeyerJM-31971–72Active loudspeaker system built by John Meyer and Bob Cavin at McCune; used at the 1972 Four for McGovern concert.Open profile →, an active loudspeaker with its own electronics; it was used at the 1972 Four for McGovern concert.

Eventide DDL 1745© Eventide Audio; photographer not credited · Copyright retained by the original rights holder; reproduced for identification and historical commentary (fair use). Reuse permission not established.McCune Sound / John Meyer JM-3© Published by ProSoundWeb; photographer and original rights holder not credited · Copyright retained by the original rights holder; reproduced for identification and historical commentary (fair use). Reuse permission not established.

At Woodstock in August 1969, Bill Hanley’s festival systemHanley SoundWoodstock PA1969Custom horn-loaded towers and remotely located loudspeakers designed for an unprecedented festival audience.Open profile → hung from two scaffold towers south of the stage. High clusters at about 70 feet covered the upper hillside, and lower clusters at about 20 feet covered the front of the crowd. Each cluster used Altec 1003B multicell horns with Altec 290 drivers over custom Hanley bins loaded with 15-inch JBL woofers. More than 20 McIntosh MC3500 amplifiers sat under the stage. There was no single console: four modified Shure M67 mixers, an Altec 1567AAltec LansingAltec 1567A Mixer1958 (in continued front-line service through the 1960s–70s)The Altec 1567A is a compact, three-rackspace, four-mic/one-line input tube mixer built around 12AX7 and 6CG7 tubes, launched in 1958 for broadcast, recording and sound-reinforcement use. Its octal accessory sockets allowed users to configure input impedances and add transformers, and an optional 'XL' cover fitted XLR connectors for portable field use. Several racks of 1567As were used by the audio crew that recorded the Beatles' August 1965 Shea Stadium concert, and the model's durability kept it in active touring and location-recording service through the late 1960s and into the 1970s.Open profile →, two Shure Audio Master equalisers and four LA-2A limiters fed the system from a scaffold platform about 75 feet into the field. The rig survived days of rain, and it also carried the stage announcements to the crowd. The achievement was organisational as much as electrical. Clair Brothers, touring since 1966, introduced its integrated S4Clair BrothersS4January 1974A compact all-in-one enclosure whose modular deployment helped define practical touring systems.Open profile → cabinet in January 1974. Showco’s touring systemShowcoShowco touring system1970Showco was founded in Dallas in 1970 by Jack Calmes, Rusty Brutsche and Jack Maxson, building its first rig in Maxson's garage before its first national tour with Three Dog Night. It engineered its own cabinets, electronics and connection systems to make complete, repeatable touring systems.Open profile → and Community’s fibreglass Leviathan horn pursued the same goal. Live desks such as Soundcraft Series 1SoundcraftSoundcraft Series 11974Soundcraft was founded in 1973 by sound engineer Phil Dudderidge (Led Zeppelin's first dedicated live engineer) and designer Graham Blyth, who had previously worked at PA/console builder Kelsey Morris. Their first product, the Series 1, offered 12 or 16 input channels feeding a stereo main bus plus monitor and echo sends, with four-band fixed-frequency EQ per channel, and was the first mixing console sold already built into its own flight case. An optional 19-pair multicore cable with stagebox let touring crews run a complete snake-and-console package, a format that became standard for rock touring PA through the rest of the decade. The upgraded Series 1S followed in 1975.Open profile →, Midas PR-series and Kelsey/Morris gave front-of-house engineers more channels to feed them.

Hanley Sound Woodstock PAJames M Shelley · CC BY-SA 4.0Altec Lansing Altec 1567A MixerJake Mohan · CC BY 2.0Clair Brothers S4© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentaryShowco Showco touring system© Courtesy Rusty Brutsche, via FOH magazine · Rights retained by the rights holder; reproduced for historical commentarySoundcraft Soundcraft Series 1© Published by ProSoundWeb; photographer and original rights holder not credited · Copyright retained by the original rights holder; reproduced for identification and historical commentary (fair use). Reuse permission not established.

Integrated boxes also came from frustration. In 1971 Harry McCune, Jr. was losing money re-coning blown Altec drivers, and asked John Meyer for a three-way loudspeaker in one cabinet, small enough for a jet cargo hold but ten times louder than an Altec 604. With chief engineer Bob Cavin and carpenter John Burke, Meyer produced the horn-loaded JM-3McCune Sound / John MeyerJM-31971–72Active loudspeaker system built by John Meyer and Bob Cavin at McCune; used at the 1972 Four for McGovern concert.Open profile → in early 1972, driven by three Crown amplifiers through a per-band limiter and Cavin’s zero-phase crossover. Its first gig is disputed, but within months it was carrying Creedence Clearwater Revival’s final tour, and Abe Jacob used it to rescue the sound of Jesus Christ Superstar on Broadway.

McCune Sound / John Meyer JM-3© Published by ProSoundWeb; photographer and original rights holder not credited · Copyright retained by the original rights holder; reproduced for identification and historical commentary (fair use). Reuse permission not established.

FOH magazine’s year-by-year chronology shows how crowded the decade became. In 1970 Bob Heil built a large four-way system for the Grateful Dead, powered by home hi-fi amplifiers; Clair Brothers switched to more robust JBL drivers and, by 1971, was hanging a two-way, 360-degree cluster for Elvis Presley, while the newly founded Showco built him a two-way system of its own. JBL’s 2440 compression driver, with a 4-inch voice coil, outlasted rival drivers at rock levels. Electro-Voice put Thiele-Small parameters on woofer data sheets in 1972, and D.B. Keele developed constant-directivity horns there in 1973. In 1974 Gene Clair and Stan Shaak built the S4Clair BrothersS4January 1974A compact all-in-one enclosure whose modular deployment helped define practical touring systems.Open profile →, a four-way, 405-lb all-in-one cabinet, and Keny Whitright designed Showco’s four-way M4; at Oakland Coliseum, Cal Perkins’s fully horn-loaded FM Productions system carried the CSNY reunion. Tasco’s system for The Who at the Valley in 1976 entered the Guinness Book of World Records as the loudest concert, at 126 dB 100 feet from the loudspeakers.

Clair Brothers S4© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentary

The Grateful Dead’s 1974 Wall of SoundAlembic / Grateful DeadWall of SoundMarch 23, 1974Separate arrays for musical sources, located behind the band, assembled into a single monumental structure.Open profile → carried the idea to its limit. Instrument-specific arrays stood behind the band, and differential microphones cancelled the PA’s own sound. Accounts often inflate its wattage. Its lasting lesson was that the system itself could be designed as one modular instrument, an idea modular touring would industrialise.

Alembic / Grateful Dead Wall of SoundRon Wickersham · CC BY-SA 4.0

Moving the gear from show to show became its own discipline. Early rigs travelled in homemade trunks and borrowed boxes; ProSoundWeb’s road-case history credits Chuck Vallas’s Anvil Cases, founded in California in 1952, with the first dedicated transport cases for touring musicians — birch plywood, protected edges and heavy hardware. In late-1960s London, Peter Ross and Chris Sherwin saw an imported American case, built their own improved version, and CP Cases spread through the roadie grapevine to acts including The Who, the Moody Blues and Deep Purple. Case makers later borrowed the airline industry’s ATA 300 packaging specification, first published on August 1, 1960, as the construction benchmark behind the “ATA-rated” case: Category I construction calls for plywood walls, riveted aluminium edging, ball corners and bonded cushioning that survives repeated drops. That borrowing was informal — ATA 300 was written for airline cargo, not concert touring — but it gave buyers a shared way to judge a case’s toughness.

Interconnection hardware and wiring conventions settled unevenly. The latching connector the industry still uses descends from James H. Cannon’s Cannon Electric “X” series: a latch added around 1950 produced the XL, and synthetic-rubber insulation by 1955 gave the part its XLR name. Polarity did not standardise with the connector. The foreword to the AES14 connector standard records that Ampex wired its machines pin 3 hot from 1950, while rival Magnecord adopted the opposite pin 2 hot convention at about the same time — two American practices that would coexist for four decades. Most American equipment remained pin 3 hot into the late 1970s, so a balanced line could arrive polarity-inverted depending on whose gear it passed through; the full resolution belongs to a later era.

David K. Kennedy's FOH loudspeaker survey fills in the portable side of the decade. Shure's 1967 Vocal MasterShure Brothers Inc.Shure Vocal Master VA300/VA3011967The Shure Vocal Master combined a six-channel, all-transistor mixer with a 100-watt power amplifier and built-in spring reverb in a single console chassis, driving a pair of dedicated column loudspeakers. Aimed at bands who could not afford custom touring PA, it became the ubiquitous 'bar band' and small-venue vocal system of the late 1960s and early-to-mid 1970s rock circuit. Shure continued to sell and service the VA300 line into the late 1970s, with the surviving factory operating/service manual documenting its six-channel mixer section, anti-feedback switches and reverb controls.Open profile → columns were, he argues, the first successful packaged portable P.A., used by Frank Sinatra and Elvis Presley for vocals and monitoring. In the late 1960s Sunn and Tycobrahe built portable three-way concert systems for clubs and touring acts, with Tycobrahe co-founder John Judnich credited by some with the first integrated active three-way concert loudspeakers, and Charlie Watkins' WEMWatkins Electric MusicWEM vocal PALate 1950s–1960sBritish column systems and mixers designed to carry vocals over increasingly loud guitar amplifiers.Open profile → festival stacks debuted at the 1967 National Jazz & Blues Festival before the 1969 and 1970 Isle of Wight festivals. By Kennedy's account, Clair Brothers' 1970 Slant Monitor was the first robust dual-driver floor wedge, establishing the touring monitor format.

Shure Brothers Inc. Shure Vocal Master VA300/VA301© FOH magazine; photographer not credited · Rights retained by the rights holder; reproduced for historical commentaryWatkins Electric Music WEM vocal PA21st CENTURY GREENSTUFF · CC BY 3.0