The Great Ambisonic Flea Circus

Legendary Ambisonic sound reinforcement pioneer, John Whiting, expounds the theory and practice of Minimalist Technology

From Audio Media, Issue 60, November 1995

Amplified musicians and their service industries are caught in the trap of conspicuous consumption. New and more sophisticated equipment is constantly relegating last year's gear to the junk yard. Not only must hire companies regularly write off thousands of pounds worth of perfectly good units as obsolete, but the performers never have time to learn how to use them. How good would pianists be if pianos had appeared on the market a couple of years ago, inevitably to be superseded the year after next? A friend who services the digital treatment devices of the famous and the near-famous tells me that most of their user memories are empty--the equipment's, I hasten to add.

At the same time, the financial squeeze is imposing severe restraints on all but the most high-profile performers. The cost of digital gizmos may be falling, but those of us who supply and operate sound systems for the less-than-rich are forced to keep our charges low, even though bills for repair, transport and everything else have gone through the roof. It is therefore tempting to trot out a rack of cheap new veeblefetzers to impress the clients and the punters while struggling along with the same old speakers and amps, driven to ever more destructive levels by the demand for higher and higher output.

But what does this matter if the cumulative decibels of a lifetime's aural self-abuse have made it impossible to detect gross distortion, let alone subtlety of effect? To protect themselves, some musicians have taken to wearing ear-plugs, usually too late. What would we think of a painter who confessed to a hobby of staring into the sun, a chef who guzzled Tabasco sauce, or a politician who listened to his own speeches? As for the punters, they'll spend their old age watching mime shows.

Don't Count the Dots

I was lucky in that my own career led me off the battlefield and into the happy hunting ground of Ambisonics. This by-product of the Soundfield microphone grew out of the attempt to develop a domestic four-speaker system that would accurately reproduce Ambisonic recordings in the home. Its inventors, in fact, warned that the system would not work properly in a space larger than a rather generous living room.

However, my own experience of demonstrating the four-speaker system in the middle of large open-floored halls and listening to it from both inside and outside the rectangle convinced me that the effect would be quite dramatic in a large church or concert hall, since natural reverberation would tend to fill in the gaps between the speakers and produce a 'blanket' of sound. It would not be as accurate as the line-on-the-wall precision of small-scale Ambisonics, but this rarely occurs in concerts of live instruments, even when they surround the audience: the reflected sound can confuse the ear to the point where it contradicts the eye. As in pointillist painting, you should enjoy the effect, not try to count the dots.

Accordingly, ten years ago I bought an Ambisonic Pan Rotate unit (thanks to a generous discount from Mike Bevill of Audio+Design) which allowed the independent panning of eight separate inputs. This, in conjunction with a tiny Minim AD-10 decoder, a Soundcraft 200 mixer modified to supply direct post-fade outputs, a couple of Quad 520 amps, and four pairs of Tannoy Lynx speakers, provided a usable if basic system.

Wild Things

Its public debut was planned for the Glyndebourne Opera production of Oliver Knussen's Where the Wild Things Are, based on Maurice Sendak's classic children's book. Sendak designed the fantastic sets and costumes, and the Ambisonic sound system was to send the voices of the Wild Things whizzing dramatically around the small opera house.

But the Pan Rotate system was late in arriving and its first tryout had to be delayed until the dress rehearsal on the first day of performance. On the way to Glyndebourne, the Fates decreed that my van would be involved in a pile-up on the A23, which resulted in my being towed up to the stage door too late for the rehearsal. So I had to quickly set up my gear in a corner box and mix the first performance strictly by theory, hoping that the system was working the way it was supposed to. I was later assured that theory and practice had coincided. (According to a German proverb, this means they're probably both wrong.)

This was the basic system with which I toured across Europe and America for the next few years in the company of Electric Phoenix, an avant garde vocal ensemble with which I've worked since 1979. The day it appeared on the market I added a Yamaha DSP-1 Digital Sound Field Processor, an inexpensive surround sound reverb unit aimed at the luxury domestic user. This became our 'portable cathedral', transforming dry multi-purpose halls into reasonable facsimiles of Westminster Abbey. The system served us well in those simple far-off days, both in our solo recitals and in our joint tours with the Kronos Quartet, together with whom we had commissioned a small repertoire.

Since my work is with 'classical' electro-acoustic musicians, I have been able to concentrate more on quality than on quantity. Not only are the power requirements much lower than in pop music, but the speakers often have to keep a low visual profile as well. One of my most satisfying concerts was with the Dufay Collective at the Queen Elizabeth Hall, providing a modicum of invisible and undetectable assistance for their delicate instruments by means of PZM mics on the floor under the musicians. I knew I'd succeeded when a sackbut player I'd once worked with asked me during the interval what I was doing there.


Because of widely varying requirements, I adopted a 'building block' approach in which I concentrated on a single small speaker design that could be multiplied as needed. This, together with the fact that I often have to work alone, led me ultimately to one of the most remarkable speakers I've encountered, the Meyer UPM. Designed as fill speakers to fit under balconies and in other confined spaces, they are so small and light as to be easily flight-cased in pairs, together with their limiter/phase/EQ control units. With threaded plates on both ends and sides, they can be mounted on any light bar strong enough to hold a spot, or even on mic stands. Having the relatively high impedance of 16 ohms, they can be driven off a single channel in groups of up to four without presenting a ridiculous load to the amplifier. Finally, their extended frequency response and lack of colouration at low levels have made them my usual near-field monitor for classical location recording.

If the UPM is beginning to sound like the Schmoo, Li'l Abner's mythical beast that supplies every human need, you're not far off the mark. Like Schmoos, they're also indestructible: on one occasion at Glyndebourne, a ton of flying scenery with defective brakes landed on two of them which were suspended underneath and didn't even scratch the paint!

These speakers are an illustration of a basic principle I've come to believe in: great technology is a product not just of expertise, but also of the whole philosophical outlook of the designer and of his backers. John Meyer got his early experience building gear for the Grateful Dead, a group always known for their integrity, their search for excellence, and also their imaginative generosity: today they run a trust fund which, among other things, helps to sponsor British composers that their own country is too mean to support. A couple of years ago I learned that Phil Lesh and Jerry Garcia had played together pre-Dead on KPFA, a funky listener-supported FM station in Berkeley, California, while I was on the staff there in the early sixties. And John Meyer, I discovered, had been one of the boy geniuses who hung around the engineering department--the son of two of my fellow-producers.

All of us at KPFA learned a valuable lesson: nothing is worth doing unless you really believe in it and wake up in the morning thinking, Oh boy! Back to work! Five years ago John Meyer let me have my first four UPMs out of demo stock at half price; recently he has supplied delicate, highly sophisticated surround sound amplification for Loren Rush, an experimental California composer who was also part of the old KPFA gang. Everything connects.

The high impedance of the Meyer UPMs meant that I had to drive them with more power than one would expect for such a small speaker, about five hundred watts per channel. For eight speakers used separately, you're therefore looking at four stereo amps of 1000 watts each. For ease and rapidity of adjustment, I keep both the Meyer control units and the amps near me in the hall, which means that the collective fans could blow up quite a storm. The answer was another unorthodox choice, the Carver TFM 42, which was their top-of-the-line domestic transistor amp. Its unconventional low-power transformer means that, not only do they stay cool without fans, but they are also so small and light that two of them in a flight case only weigh about fifty pounds. They weren't designed to travel, so it was necessary to do a bit of internal reinforcement and also to treat them with gentle respect.

My Soundcraft 200 was eventually replaced with a Mackie 1622, smaller and lighter but battleship-rugged and including as standard certain features I needed such as direct outs and extra aux sends. The EQ is minimal, but I don't find this a problem in classical sound projection. Drastic equalising to minimize feedback is necessary at high levels, but at the modest output at which I generally work, it simply skews the frequency response to no purpose. Don't wear a fur coat when the sun is shining.

Great Leaps Forward

A problem I frequently had to face was mixing from an eccentric position such as the front row or a far corner, in which I was forced to take distribution on trust. For location recording, I was already using The Box, an ingenious diamond-shaped light display that gives you a read-out of stereo width and phase information. It occurred to me that two of them, one mounted upside down under the other, could provide an accurate picture of the whole Ambisonic area. Philip Stokes, who now makes them, obliged, and I both solved my problem and acquired a mesmerizing display for the audience to stare at. I had gone multi-media!

In the meantime, I was casting an envious eye at the rest of Audio+Design's Ambisonic package, including their decoder, which would free the little Minim box for my playroom, and an add-on Ambi-8 decoder which would give me a discrete eight-channel projection system. Last year A+D, after a long thankless effort to sell Ambisonics to the world, decided to get rid of their units at half-price, just at a time when I was able to persuade two festivals, in London and Germany, to help me make the Great Leap Forward. I already had eight speakers and a couple of spare amps; I only needed four more Meyer control units. Meyer obligingly brought out a stereo version of their mono boxes, which cut the cost almost in half.

The result was beyond my wildest dreams. Ambisonics is such a robust system that it is very tolerant of the asymmetric speaker placements required by many halls. In a very wide, shallow performing space it can be spread out across the back of the stage area like a gigantic cinerama screen. In the Barbican I ended up with a huge kidney shape whose convex rear edge skirted the fronts of both the upper and lower balconies. In halls where full occupancy of several balconies makes true surround sound impractical, the system works extremely well tipped up on edge in front of the audience, so that one observes, from outside it, a hologram of sonic space. The placement of the human ears on either side of the head means that our horizontal discrimination is much more sensitive than our vertical, so the height of the system needs to be approximately twice the width.

The two A+D decoders work together in such a way that the original four outputs are available in addition to the final eight. This means that I can still use the double Box visual read-out and also feed easily mixed signals to a pair of bass bins, which were the final touch the system needed. Meyers would have been nice, but I couldn't afford a second mortgage or an articulated lorry to transport them. A firm with the cheeky name of ASS (Acoustic Sound Systems) offered a pair of highly efficient bass reflex cabinets containing eighteen inch drivers with five inch voice coils, all for under a grand. The indispensable Philip Stokes designed a pair of low-pass filters that would mix the four outputs either left/right or front/rear. I power the bins with a mere 125 watts each from a pair of Quad 510 mono amps, whose input-output LEDs give reassurance that both the filter outputs and the amps are working. The bass cut switch on the Meyer control units keeps the UPMs and their Carvers from wasting energy at the bottom end, which is covered by the bins--the whole system thus operating as a rough-and-ready form of bi-amping.

Amplified Orchestra?

The end result of all this Heath Robinson tinkering has to be heard to be believed. One eminent 'classical rock' musician mixed a composition of his own for amplified orchestra and pre-recorded tape, and declared afterward that it was perhaps the best sound system he had ever used. Considering that he was accustomed to a no-expense-spared state-of-the-art system that had been written up in one of the top professional journals, I was more than a little pleased.

'Amplified orchestra?' I hear you mutter. 'That must have cost a fortune in microphones.' Indeed it would, without the lateral thinking of Mike Skeet, well known to these pages. I already had my eye on Tandy's miniature back electrets, but was stymied by the fact that their output was unbalanced. Mike conceived the brilliant idea of using strong die-cast boxes to accept inputs from two mics, each feeding down one leg of a balanced line. To allow the use of the boxes with only one mic, a resistor was inserted across each input socket, which was disconnected when a mic was plugged in. The two microphones were, of course, out of phase, which was not a problem with close miking. It helped to minimize spillage from other nearby instruments and also to raise the feedback threshold. An elegant variation was later carried out by Philip Stokes, who installed all the mic electronics inside the boxes and modified them for phantom power. Twenty-four high-quality miniature mics for well under a grand, and only requiring twelve mixer inputs!

Other mics used in the system include, for classical vocal work, AKG C451s with CK22 capsules. These almost unknown omni capsules, which were designed years ago in consultation with the BBC, are close to pop-proof with the addition of simple foam screens, and sound so similar to B&Ks as to be unnerving. I've accumulated fifteen of them, which for recording I can scatter all over an orchestra to help the Soundfield stereo balance as needed, without altering the sound quality.

However, in live performances of Luciano Berio's Sinfonia for eight amplified voices and orchestra, omni mics presented insuperable problems of feedback and spillage; what was needed was a rugged dynamic hand-held cardioid that sounded like an omni condenser. I was introduced to the Shure SM59 by Hugh Macdonald, who had used them with the Swingle Singers in many performances of the Berio. Unlike the ubiquitous SM58, it has very little proximity effect, is extremely pop-resistant, and has a frequency response so flat and extended that a slight boost at the top can make it sound like its much more expensive rivals

In fact, it makes singers sound like they really sound--so of course it had to be discontinued. I learned from a Shure rep at an APRS show that the SM59 had been conceived and designed entirely by engineers, to be built to a standard, not to a price. No wonder it bombed. B&K, now the flavour of the month, would have gone broke years ago if they had been forced to rely on musicians rather than acoustic research scientists to keep them afloat until the recording industry finally woke up to the fact that they were the truest easily available microphones in the world.

Digital Museum

The final problem I had to deal with was the playback of pre-recorded tapes that included a click track for the performers. Since some tapes were Ambisonic, this would have required at least five tracks of an eight-track deck. The Ambisonic four tracks I was able to reduce to stereo through UHJ encoding, which could then be decoded back to their original format; the click was accommodated on the audio track of a Beta hi-fi video which carried the digital PCM signal.

But then PCM became another museum technology. My subsequent experiments confirmed that two identical DAT recorders, started together from the pause mode at a common program ident, will remain in synch for as long as half-an-hour. They are not, of course, phase coherent, but they are tempo coherent (phase and tempo being adjacent segments of a single temporal continuum). In other words, the two machines remain about as closely in synch as the outer tracks of a large analog multitrack. So multitrack recordings including a click could be transferred simultaneously to two DAT recorders, inserting a common ident just before each cue. One machine carries the program, the other the click plus the program in mono on the other channel, for constant stop-and-replay use in rehearsals. (One famous electro-acoustic group performs with single program/click DATs, the equivalent of my practice tapes, which the audiences necessarily hear in mono. What a waste of a composer's time and effort!) [Note: This, alas, was the Kronos Quartet. I hope they’ve moved on. . .]

The DAT recorder I finally settled on was the now-extinct Sony TCD-D3. They are delicate and expensive to repair, but the sound is excellent; and Sony produced, for a brief instant, an accessory box that includes an infra-red receptor, a stacked pair of which allows two machines to be started in synch by a single remote control. This in turn I had accessed to the pause control by a hard-wired foot pedal down a mic line, so that a musician on stage can start the tapes repeatedly to exact cues. Stopping and re-cueing is accomplished back at the desk, digitally (i.e., with my finger). The whole system fits in a small attaché case. [Beginning in 1997 I used MiniDisk recorders, which were much more reliable and convenient for concert use.]

Even ordinary stereo tapes can benefit from Ambisonic projection. Roger Furness had incorporated a 'stereo enhance' option in his Minim decoders, in which mid-side processing utilised phase, location and amplitude information to create a highly complex and precise Ambisonic sound field: a black box with taste! This was lacking in the up-market A+D decoder, so Mike Skeet designed and built an add-on box that would perform the same function and also carry out miraculous corrective surgery on defective stereo masters. 'We'll fix it in the mix' thus became 'We'll fix it after the mix.'

Toys R Us

To some of you, all this must sound like Toys-R-Us. But the truth is that serious electro-acoustic musicians often work within space, time and money restrictions that the prosperous end of the pop world would find unacceptable. Many concert venues lack a high-quality sound system, the installation must be set up and running in a couple of hours, and the budget usually limits the crew to the mixer and, if he's lucky, a roadie. (My definition of an electro-acoustic sound designer is a stevedore who can read music.) But some classical musicians who have crossed the Rubicon into pop will privately admit that embracing the Big Bang has changed the whole nature of their musical output in ways they regret. So I work with exponents and practitioners of:

Minimalist Technology: i.e., equipment which is sustainable (no rupture of eardrums) transportable (no rupture of vehicle springs or personnel) affordable (no rupture of bank account)

In our world Small is Beautiful. The rig travels all over Europe in a VW Transporter, with plenty of extra room for a comprehensive library of restaurant guides and wine atlases, plus local vintages, sausages and cheeses picked up along the way. It's a good life. Applications to go on the waiting list of deputy roadies may be sent c/o October Sound. But don't expect to get rich. Contemplate the following exchange from Woody Allen's Manhattan:

--I've got a new job: I'm the dresser at a burlesque house.
--Wow! What's the pay?
--A hundred a week.
--That's not very much.
--Yeah, I know, but it's all I can afford.

John Whiting