The Bell Sound: from ALICE to AMY

Just as the folks inside the Sound-House of the BBC’s Radiophonic Workshop continued to refine their approach and techniques to electronic music, another older sound house back across the pond in America continued to research new “means to convey sounds in trunks and pipes, in strange lines and distances”. Where the BBC Radiophonic Workshop used budget friendly musique concrete techniques to create their otherworldly incidental music, the pure research conducted at Bell Laboratories was widely diffused and the electronic music systems that arose out of those investigations were incidental and secondary byproducts. The voder and vocoder were just the first of these byproducts.

Hal Alles was a researcher in digital telephony. The fact that he is remembered as the creator of what some consider the first digital additive synthesizer is a quirk of history. Other additive synthesizers had been made at Bell Labs, but these were software programs written for their supersized computers.

Alles needed to sell his digital designs within and without a company that had been the lords of analog, and it needed to be interesting. The synthesizer he came up with, was his way of demonstrating the companies digital prowess, and entertaining his internal and external clients at the same time. What he came up with was called the Bell Labs Digital Synthesizer or sometimes the Alles Machine or ALICE.

It should be noted that Hal bears no relation to the computer in 2001: A Space Odyssey. The engineer recalls those heady days in the late sixties and 1970s.  “As a research organization (Bell labs), we had no product responsibility. As a technology research organization, our research product had a very short shelf life. To have impact, we had to create ‘demonstrations’. We were selling digital design within a company with a 100 year history of analog design. I got pretty good at 30 minute demonstrations of the real time capabilities of the digital hardware I was designing and building. I was typically doing several demonstrations a week to Bell Labs people responsible for product development. I had developed one of the first programmable digital filters that could be dynamically reconfigured to do all of the end telephone office filtering and tone generation. It could also be configured to play digitally synthesized music in real time. I developed a demo of the telephone applications (technically impressive but boring to most people), and ended the demo with synthesized music. The music application was almost universally appreciated, and eventually a lot of people came to just hear the music.”

Max Mathews was one of the people who got to see one of these demos, where the telephonic equipment received a musical treatment. Mathews was the creator of the MUSIC X series of computer synthesis programming languages. He was excited by what Alles was doing and saw its potential. He encouraged the engineer to develop a digital music instrument.
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“The goal was to have recording studio sound quality and mixing/processing capabilities, orchestra versatility, and a multitude of proportional human controls such as position sensitive keyboard, slides, knobs, joysticks, etc,” Mathews said. “It also needed a general purpose computer to configure, control and record everything. The goal included making it self-contained and ‘portable’. I proposed this project to my boss while walking back from lunch. He approved it before we got to our offices.”

Harmonic additive synthesis had already been used back in the 1950s by linguistics researchers who were working on speech synthesis and Bell Labs was certainly in on the game. Additive synthesis at its most basic works by adding sine waves together to create timbre. The more common technique until that time had been subtractive synthesis, which used filters to remove or attenuate the timbre of a sound.

Computers were able to do additive synthesis with wavetables that had been pre-computed, but it could also be done by mixing the output of multiple sine wave generators. This is what Karlheinz Stockhausen basically did with Studie II, though he achieved the effect through by building up layers of pure sine waves on tape rather than with a pre-configured synth or computer set up.

That method is laborious. A machine that can do it for you goes a long way towards being able to labor at other things while making music.

ALICE was a hybrid machine in that it used a mini-computer to control a complex bank of sound generating oscillators. The mini-computer was an LSI-11, by the Digital Equipment Corporation, a cost reduced version of their PDP-11 in production for twenty years starting in 1970. This controlled the 64 oscillators whose output whose was then mixed to create a number of distinct sounds and voices. It had programmable sound generating functions and the ability to accept a number of different input devices.

The unit was outfitted with two 8-inch floppy drives supplied by Heathkit; they made their own version of the LS-11 and sold it as the H11. AT&T rigged it out with one of their color video monitors. A custom converter was made that sampled the analog inputs and transferred them to 7 bit digital resolution 250 times a second. There were a number of inputs used to work with ALICE in real time: two 61-key piano keyboards, 72 sliders alongside various switches, and four analog joysticks just to make sure the user was having fun. These inputs were interpreted by the computer which in turn controlled the outputs sent to sound generators as parameters. The CPU could handle around 1,000 parameter changes per second before it got bogged down.
The sound generators themselves were quite complex. A mere 1,400 integrated circuits were used in their design. Out of the 64 oscillators the first bank of 32 were used as master signals. This meant ALICE could be expected to achieve 32 note polyphony. The second set was slaved to the masters and generated a series of harmonics. If this wasn’t enough sound to play around with, ALICE was also equipped with 32 programmable filters and 32 amplitude multipliers. With the added bank of 256 envelope generators ALICE had a lot of sound potential and sound paths that could be explored through her circuitry. All of those sounds could mixed in many different ways into the 192 accumulators she was also equipped with. Each of the accumulators was then sent to one of the four 16-bit output channels then reconverted from digital back into analog on the audio output.   

 Waveforms were generated by looking up the amplitude for a given time in a 64k word ROM table. There were a number of tricks Alles programmed into the table to reduce the number of calculations the CPU needed to run. 255 timers outfitted with 16 FIFO stacks controlled the whole shebang. The user put events into a timestamp sorted queue that fed it all into the generator.

Though the designers claimed the thing was portable, all the equipment made it weigh in at a hefty 300 pounds, making it an unlikely option for touring musicians. As the worlds first true digital additive synthesizer it was quite the boat anchor.

Completed in 1976, only one full-length composition was recorded for the machine, though a number of musicians, including Laurie Spiegel whose work will be explored later, played the instrument in various capacities. For the most part though the Alles Synth was brushed aside; even if the scientists and engineers at Bell Labs were tasked to engage in pure research they still had business to answer to. A use was found for Hal’s invention in terms of marketing was found once again in 1977. 

In that year the Motion Picture Academy was celebrating the 50th anniversary of the talkies. The sound work for The Jazz Singer, the first talking picture, had been done by Western Electric, with their Vitaphone system technology. The successful marriage of moving image and sound first seen and heard in that movie wouldn’t have been possible without the technology developed by the AT&T subsidiary and Ma Bell was still keen to be in on the commemoration of the film. ALICE is what they chose to use as the centerpiece for the event.

A Bell Labs software junky by the name of Doug Bayer was brought in to improve the operating system of the synth and try to make the human interface a bit more user friendly. The instrument was flown to Hollywood at considerable risk. The machine was finicky enough without transporting it. Taking it on a plane where it could get banged up, whacking out all of its components in just one bump, and potentially sending it into meltdown mode was not out of the question.
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So they hired musician and composer Laurie Spiegel, who’d already been working at the Labs without pay, to be filmed playing ALICE. This would be shown in the event that the musician they hired to play it live, Roger Powell, wouldn’t be able to do so due to malfunction. This film is the only recording of it in performance left in known existence. 

Yet to hear how the Bell Labs Digital Synthesizer sounds look no further than Don Slepian’s album Sea of Bliss. Max Mathews had hired Slepian to work with the synth as an artist in residence between 1979 and 1982. Don had been born into a scientific family. From an early age he demonstrated technical talent and musical ability. He had begun making music in 1968, programming his own computers, soldering together his own musical circuits, and experimenting with tape techniques. As a member of the Defense Advanced Research Projects Agency (DARPA) Don worked as a tester on the early iteration of the internet and dor a time he lived in Hawaii and played as a synthesizer soloist with the Honolulu Symphony. All of this made him a perfect fit as artist in residence at Bell Labs.
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The results his work are on the album: epic length cuts of deep ambient music bringing relaxation and joy to the listener. It’s the audio version of taking valium. Listen to it and feel the stress of life melt away.
Don Slepian described his 1980 masterpiece for the online Ambient Music Guide. “It’s stochastic sequential permutations (the high bell tones), lots of real time algorithmic work, but who cares? It's pretty music: babies have been born to it, people have died to it, some folks have played it for days continuously. No sequels, no formulas. It was handmade computer music."

The Bell Labs Digital Synthesizer was soon to leave its birthplace after Don had done his magic with the machine. In 1981 ALICE was disassembled and donated to the TIMARA Laboratories at the Oberlin Conservatory of Music.

Oberlin, and by extension TIMARA (Technology in Music and Related Arts) has a history that reaches back to the very beginning of electronic music, in the mid-19th century. None other than Elisha Gray was an adjunct physics professor at the college. He is considered by some as the father of the synthesizer due to his invention of the musical telegraph and his seventy plus patents for inventions that were critical in the development of telecommunications, electronic music and other fields. If it had not been for Gray’s electromechanical oscillator, Thaddeus Cahill would never have been able to create that power hungry beast of an instrument, the Telharmonium.

The Music Conservatory at Oberlin dates back to 1865 and they joined the ranks of those radio and television stations who built electronic music studios with the opening of TIMARA in 1967. The department was founded by Olly Wilson as a response to the demand for classes in electronics from composition students. It became the first of a number of departments in the American higher education scene to create a space for experimentation in analog synthesis and mixed media arts.

Though ALICE is now enshrined in one of the many sound laboratories at TIMARA her influence continued to be felt not long after she was sequestered there. A number of commercial synthesizers based on the Alles design were produced in 1980s. 

The Atari AMY sound chip is a case in point and was the smallest of the products to be designed. It stood for Additive Music sYnthesis. It still had 64-oscillators but they were reduced to a single-IC sound chip. A chip that had numerous design issues. Additive synthesis could now be done with less, though it never really got into the hands of users. It was scheduled to be used on a new generation of 16-bit Atari computers and for the next line of game consoles and by their arcade division. AMY never saw the light of day in any configuration. Even after Atari was sold in 1984, she remained waiting in the dark to get used on a project, but was cut from being included in new products after many rounds at the committee table, where so many dreams wind up dead.  

Still other folks in the electronic music industry made use of the principles first demonstrated by ALICE.  The Italian company Crumar and Music Technologies’ of New York got into a partnership to create Digital Keyboards. Like Atari they wanted to resize the Alles Machine, make it smaller. They came up with a two-part invention  using a Z-80 microcomputer and a single keyboard with limited controls. They gave it the unimaginative name Crumar General Development System and it sold in 1980 for $30,000 buckaroos. Since it was out of the price range of your average musician, they marketed the product to music studios. Wendy Carlos got her hands on one and the results can be heard on the soundtrack to Tron.
 
Other companies got into the game and tried to produce something similar at lower cost, but none of these really managed to find a good home in the market due to the attached price tag. When Yamah released the DX7 in 1983 for $2,000 the demand for additive synths tanked. The DX7 implemented FM synthesis and enabled it to achieve many of the same effects as ALICE with as few as two oscillators. FM synthesis and its relationship to FM radio modulation will be looked at in detail in another article. 
It had all started out as a way for Hal Alles to look at potential problems in digital communications, such as switching, distortion, and echo. It ended up becoming a tool for extending human creativity.
 
References: 
http://120years.net/bell-labs-hal-alles-synthesiser-hall-alles-usa-1977/
https://en.wikipedia.org/wiki/Bell_Labs_Digital_Synthesizer
http://www.atarimuseum.com/computers/8BITS/XL/ASG/Chips/AMY/index.html
https://en.wikipedia.org/wiki/TIMARA

Read the other articles in the Radiophonic Laboratory series.