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History of PA (Part 2)

the birth of loud

Continuing his lessons in loudness, Ben Duncan takes the development of PA through the early seventies. Pictured below, Marc Bolan in front of a RCA W-bin with Vitavox horn on accompanying chair.

In last month's sortie, we ended up with musicians about to adopt 1940s and '50s technology in the shape of giant cinema speakers. Between 1970 and 1975, developments in sound systems, particularly the power end, the "outfront stacks" — raced at breakneck pace: in 1970, the foundations had been laid. Five years later, the last tiles were firmly on the roof. Taking the house building analogy beyond 1974, the events of the past decade have been things like plastering, wiring, and fitting the furniture, not to mention the odd domestic "scene".

Early 1970s: Speaker System developments

In the wake of Iron Butterfly's 1970 tour, Bill Kelsey and Jim Morris — working as Kelsey-Morris — put together arguably the first PA system for sale in Britain with horn-loaded speakers, AKA "bin and horn system". King Crimson, T. Rex and Alvin Lee's Ten Years After were notable owners of the early Kelsey-Morris PAs. Bass and midrange frequencies were handled by the original and truly over-the-top RCA W-Bin (so-called because the internal sound passages were W shaped).

Standing eight feet high, the W-Bin was crowned with a Vitavox radial horn treble, itself not exactly minimalist in tone. The attraction of this rig was that the hassles of weight and size were more than compensated for by the extra decibels achieved, and the vitality in the sound. The magic of high sound levels had become a fascination in itself, and if the means to this resulted in physical hardship for the humpers, well sod it.

This ties in with the fact that bands in those days were more intimately tied in with their PA rigs: deciding which PA to buy or hire would involve interminable and heated discussions between the band's members. And ownership of a PA — the larger the better — was all kudos if you were a major group. (Vomits compulsively — arrgghsplat.)

True to their cinematographic legacy, the original bin and horn PAs were simple, two-way systems. Fifteen-inch cone speakers handled the bass and midrange frequencies, with a separate, smaller compression driver for top-end. Early on, it became apparent that better results (ie clearer midrange) were on offer if the bass and midrange were split out to separate, specialised drivers and horns, this leading to the three-way system. With careful design, this meant better sound, and it always spelt more power. But the augmentation also involved more boxes, more amplifiers, more weight, and more bulk.

1971: Crossovers

The crossover also came under scrutiny at this time. Its job — to apportion the signal between the various speakers/horns according to frequency — wasn't helped by the brute force nature of its task. 1940s crossover technology went with 15- and 30-watt (gasp) drivers, but by 1971, JBL, Gauss, Fane and Electrovoice drivers rated at 150 or 200 watts were being fitted to bins, so no wonder the crossover, operating between the power amps and the speakers, couldn't cope. Even heavy-duty crossovers were apt to soak up lots of power, upset the sound, and occasionally go up in smoke... The first improvement came right away, in 1971: Kelsey-Morris placed the crossover network ahead of the amplifier. This took the crossover out of the dicey high-power region, so it shrunk dramatically in size. The (passive) circuit was simple, needed no power, and for bands like Pink Floyd, it was built — at their insistence — in an Old Holborn tin.

1972: Active Crossovers

The original Midas PA, designed by Jeff Byers and Chas Brooke (with advice from Scott Thompson of Colac PA hire who'd picked up ideas while touring in the US) took the development a stage further in 1972: a rig sold to Supertramp featured active crossovers for the first time. These were more complex, and needed power, but gave the much needed flexibility in setting levels and crossover frequencies at a time when people were experimenting willy-nilly with many different speakers, cabinets and multi-speaker driving arrangements. From this point up to the early 1980s, there was a further division. Some companies, like Kelsey-Morris, wanted to keep things simple, and stuck doggedly to two- and three-way systems, but in other rigs the signal was split into four, five, six or even seven frequency bands, with a specialised array of horns or bins for each. With care, this artifice could work to make the system sound better — especially in the midrange — but more often it made already poor PAs sound simply execrable, not to mention adding considerably to the size of the stack and the complexity of the interwiring.

Back with Kelsey-Morris, a typical three-way system in 1972 incorporated Electrovoice 1829 or JBL top-end drivers, a JBL K120 (12in Cone speaker) in the mid, and 15in JBL drivers on bass. It was at this time that Bill Kelsey met an Australian (sic) maintenance engineer from Granada studios called Dave Martin who wanted to get into speaker technology. By now, people had tired of lugging W-Bins. So Dave Martin was commissioned by Kelsey-Morris to come up with a much smaller yet equally "pokey" bass bin. The original Martin bass-bin with the famous flared front was a development of Paul Klipsch's "La Scala", a cabinet designed in the 1950s.

1974: Compact Systems

Around the same time there was a friendly rivalry with Tony Andrews, who'd been experimenting with horn speakers as early as 1970. He'd built a number of innovative PAs, most notably for the Pink Fairies and Pete Brown's Piblokto, and also painted his cabinets pink — or purple! Subsequently, Kelsey-Morris employed Tony Andrews to design and construct compact, high-power speakers after Dave Martin had gone off (amidst some acrimony) to set up Martin Acoustics. In 1974, Martin joined forces with Midas and together they pioneered the concept of a modular, package PA, wherein all the components (ie amps, speakers, crossovers and desks) were matched. The Martin-Midas PA was four-way, and later (1975) included Dave Martin's visually memorable M212, better known as the "Phillishave" bin! This used two 12in cone drivers to handle low midrange frequencies, and was something of an improvement over the compression drivers used hitherto; they were apt to be "honky" and rip people's ears. Also of note, Midas produced the first integrated multi-amp. The Midas "Block" was a large, flight-cased enclosure containing the four amplifiers (totalling 1kW) needed to drive the bass, low-, mid-, high-mid and top-end speakers of each stack.

The Hire Companies

As a power-at-all-costs syndrome developed, rigs were soon sporting several kW of horn speakers, equal in sound level to tens or hundreds of column speakers. Inevitably, the cost and sheer logistics of the PA became prohibitive, even to the major bands, especially since rapid developments made continual chopping and changing necessary if the PA — as a status symbol — wasn't going to get left behind. A direct result of this was the rise of large hire companies from 1970 onwards, coincident with a boom in touring. Rock'n'roll equipment rentals suddenly became big business, and the finer details of developing clean, accurate, high-powered sound systems was all too often pushed aside. (We could say that some very, er, naughty things happened in them early days...)

The original big hire company was Dave Hartstone's IES (International Entertainments). To quote Tony Andrews, "It used stock JBL garbage." That is, standard JBL horns developed for auditoriums, "But it was the loudest thing around at the time." IES also moved into the US on the back of the big Led Zeppelin and Rod Stewart tours of 1971-73. But by 1973 it had flowered, and Dave Hartstone sold up.

The flux of politics and technological development in PA was undoubtedly focused most strongly on the personalities involved in and around Kelsey-Morris, and Electrosound. When Morris "went elsewhere" in 1974, Bill Kelsey joined up with Electrosound, a hire company founded by Rikki Farr, who'd promoted the Isle of Wight Festivals. A year later, Electrosound took a share in the US hire business, buying up Tom Fields Associates with Pink Floyd's investment money, becoming TFA-Electrosound in the process. (Much later, in 1981, TFA was taken over by Theatre Projects, in the wake of the Norton-Warborg scandal, again involving the Floyd's loot.)

The other major rigs were less to do with the pure development of sound than industrial plant hire: Entec (Entertainments Technicians) were tied in with the Marquee and Harold Pendleton, so they did the Reading Festivals. And TASCO (The American Sound Company!) was founded in 1970 on a £20k loan from Jim Marshall; it was a development of MEH (Marshall Equipment Hire), was operated by Joe Brown, and has on all accounts been mostly concerned with business.

Over in the US, hire companies were perhaps slower to cover the ground, hence the UK invasion. And in any case, Roy Claire led the field in his home country from the start. In 1971, the Claire Bros introduced the S4, a compact, full-range PA enclosure. Here, the three speakers needed to cover the bass-, middle- and top-end were in a single, cogent cabinet, repeated many times, rather than a conventional stack with all the bass bins in one untidy pile and the mids in another. The problem with the full range cabinet was dispersion and interactive effects between the speakers — other people tried it in the UK, but without much success.

In the US though, the massive cost of unionised "humping" labour forced attention on making the load-in and pulling-down times as brief as humanly possible. So the Claire Bros overcame these technical setbacks out of sheer need, knowing that the market for S4-based rigs would be overwhelming. Why? Well, because the several thousand dollars saved by halving the rigging times would more than pay for the hire of the PA!

1975: No EQ, No Backstage Pass

Although stage monitoring had made an appearance in 1968, it didn't altogether sort itself out until the mid 1970s. In 1973, for example, each member of Emerson Lake & Palmer had a complete monitoring system to himself, including an Audiomaster mixer and, of course, an engineer to drive it all. This situation was inevitable pending development of the special hardware for the job: in 1975, Midas introduced purpose-built monitor desks with six or more outputs, one for each musician's monitor. Prior to this, and assuming you weren't as wealthy as ELP, and weren't hiring Kelsey-Morris, the monitor signals originated from the outfront desk. Even if the four or so monitor "sends" provided were sufficient, the engineer outfront was invariably too busy, doing other things — or just too distant to give proper attention to the needs of each of the musicians on stage.

Meanwhile, back outfront, mixers moved on from WEM's Audiomaster (it had five channels, but two or more were often linked together), to Mavis, and then on to Midas, where the box of Knobs acquired a new, upmarket name — the desk. It was Midas who put the standard PA desk on the map and gave it facilities commensurate with the more sophisticated consoles that were by now in use in studios, such as multiband sweep EQ and subgrouping.

Next month, Ben Duncan finishes off with the plastering and the wiring, and brings the story of everyday PA people up to date.


Read the next part in this series:
History of PA (Part 3)

Previous Article in this issue

Deptford Duotone

Next article in this issue


One Two Testing - Copyright: IPC Magazines Ltd, Northern & Shell Ltd.


One Two Testing - Jul 1984

Donated & scanned by: Simon Dell




History of PA

Part 1 | Part 2 (Viewing) | Part 3

Feature by Ben Duncan

Previous article in this issue:

> Deptford Duotone

Next article in this issue:

> Shredder

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