The History of EMS Part 1

via Bitexion on VSE

"This is copied off the Analogue Systems user manual, since they have two cloned EMS modules in their line, the filter and trapezoid. Not written by me. Part 2 comes later, it's 10 pages of tightly written text.

The most interesting parts are the part about the awful control voltage scheme internally, and the quirky DK1 keyboard. Here you go. This part deals with the VCS3 and why it is said to be an effects machine. The next parts will deal with the success and fall of the company, no time to write all that down now.

THE EMS STORY

IN THE BEGINNING
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Peter Zinovieff was born in London in 1933. A geologist who filled his home with samples (rocks, not audio) he was fascinated by electronic music, and used his wealth to develop a huge voltage controlled studio that occupied an entire room at his home in Putney.

When this became too unwieldy, he enlisted the help of engineer Dave Cockerell and programmer Peter Grogno, who helped him design an enhanced system. This used two DEC PDP-8 minicomputers to control the voltage-controlled modules of Zinovieff's early synthesizers. Their "MUSYS" system proved reasonably user-friendly,with a QWERTY keyboard and a velocity sensitive piano-style keyboard, much like today's computer-based studios.

Zinovieff's ideas and instruments were incredible. Twenty years before modern computing and sequencing packages, Zinovieff's PDP-8s could store and replay compositions, complete with sound shaping parameters. His software was even capable of twisting the music into bizarre new sounds and effects. In 1968, Zinovieff and Cockerell also invented a form of computer-controlled spectral (or 'additive') synthesis, using a system of 60 resonant filters that could analyse sounds and resynthesize them.

In 1969, when MUSYS became too expensive for Zinovieff alone, he decided to offer it 'to the nation' as a free resource for the arts. To this end, he placed an advertisement in The Times. Fortunately, a gentleman named Don Banks misunderstood this offer and, in return for a cheque for £50, he asked Zinovieff to "make me a synthesizer". So, together with Tristram Cary, a composer for electronic music for TV series such as "Dr Who", Zinovieff and Cockerell created a new company, Electronic Music Studios Ltd, and produced its first synthesizer. Cockerell's "VCS1" was a hand-built rackmount unit with two oscillators, one filter and one envelope. In an era when any synthesizer was, almost by default, a huge modular, this was not thought to be adequate, so the partners enhanced Cockerell's initial ideas, designing an instrument that was small, but powerful and flexible. It was the Voltage Controlled Studios no.3- The VCS3

THE VCS3
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The VCS3 is, essentially, a modular synth that comes in two parts. The synth itself - nicknamed "The Putney" because EMS was located in that part of London - contains the bulk of the audio modules. It also incorporates two power amplifiers and speakers, making it a self-contained sound-effects generator.

Oscillators 1 and 2 are the primary sound sources, and these produce a remarkable range of frequencies, from below 1Hz to around 10KHz. Osc1 produces sine and sawtooth waveforms with a form of rectifying waveshaping for the sine wave. Independent level controls allow you to select the amounts of each waveform in the oscillator's output. The second VCO also produces two simultaneous waveforms, and again it offers independent level controls for each. This time, the waveforms are pulse and triangle waves, with simultaneous waveshaping from 0% to 100% on the former, and from sawtooth to ramp wave on the latter. It's a shame that, on an unmodified VCS3, none of the waveshapers can be voltage controlled, because this would introduce many forms of PWM and dramatically increase the range of sounds available. But there it is... Once selected, a waveform is static. A third VCO is similar to VCO 2, with pulse and triangle waveforms, but its frequency range is concentrated further down the spectrum, lying between 0.025Hz and 500Hz.

An independant section on the panel contains a noise generator, with a level control and a 'colour' control that varies from predominantly low frequencies (red) through 'white' noise, and up to predominantly high frequency (blue) noise. Another section contains the Ring Modulator which, as you would expect, offers just an output level control.

Many players and writers have described the VCS3's filter as a conventional lowpass filter with an 18dB/octave slope, but they are - to some extent - wrong. For one thing, the VCS3 filter exhibits a 'knee' in its cutoff profile; the first octave above the cutoff frequency rolls off at 12dB/octave, but the slope increases to 18dB/octave at frequencies above that. Furthermore, any amount of filter resonance significantly depresses the low frequency gain, so EMS described it as a combined low-pass/band-pass device. At high Response (the EMS term for 'resonance') the filter self-oscillates. This was mind-boggling stuff in the late 60's.

If the filter is unusual, the envelope generator (which EMS called a 'shaper') and its associated VCA are positively arcane. It has six controls. The first is straightforward enough - it's the Attack, which has a range about 2ms to 1s. So far, so good. The next control is laballed "ON", but nowadays we would call this a ustain level "Hold" because it determines the length of time the envelope stays 'high' after you release the gate. Control number three is more recognizable - it's a Decay rate, with a claimed range of 3ms to around 15 seconds. The fourth knob is labelled "OFF" and it determines the delay before autoretriggering of the envelope cycle. Until you understand that this must be in the '10' position (called 'Manual') to play the VCS3 conventionally, things can get very confusing. Indeed, the envelope will auto-repeat at frequencies of up to 60Hz, which is well inside the audio range, so the 'Shaper' can also act as an LFO or even as a deep bass oscillator.

The envelope has two outputs with independent level controls. The first (and the fifrth in the 'shaper' section) is the one that confuses most people: it's the "Trapezoid" level. To understand this, just picture an envelope produced by an AHD (attack/hold/decay) contour generator. This is a shape called a trapezoid. So the Trapezoid Level simply determine the level of the envelope CV. The second level control (the sixth shaper control) is the signal level, and this controls the loudness of any signal passing through the Shaper. There is a lso a large, red ATTACK button, which we would nowadays describe as a manual Gate.

The VCS3 also provides a spring reverb with Mix and Level controls. This is a simple dual-spring device, with a maximum reverberation time of approx. 2 seconds. Unfortunately, when using the VCS3's internal speakers, the reverb howls uncontrollably before the mix gets very dense, and you can only use it to its full potential with external amplification and speakers.

It may not be obvious at first sight, but the VCS3 is a stereo synthesizer with independent output channels A and B that drive the left and right speakers respectively. These have independent level controls, panning controls, and output filter that, depending upon position, attenuate the bass or trable, or porivde a flat response.

Performance controls are limited to the enormous X/Y joystick. This has two controls that govern the X and Y ranges but, unfortunately, its maximum range is about +/-2V, so it's not often that you can plumb the extremes of any parameters it controls. There is also a
voltmeter that allows you to measure any control voltages (which are close to DC) or signal levels (which are AC) within your patches. You can even connect an oscilloscope to a dedicated 1/4" output on the rear.

THE DK1 KEYBOARD
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The separate DK1 keyboard - known as "The Cricklewood", because that was where Cockerell worked - was as radical as the VCS3 it controlled. Of course, it was monophonic (there were no poly synths in 1969) but it was velocity sensitive, allowing players to add expression in a
way that had hitherto been impossible.

You connect the DK1 to the VCS3 using a dedicated 8-way cable that provides two power rails, two CVs and a Gate pulse for the envelope shaper. To the left of the keyboard itself, two switches control the two output CVs (called 'Channels') produced by the DK1. The first of these has 'Signal' and 'CV1' positions. We'll come to signal in a moment...for now, simply understand that CV1 was what we would now call pitch CV. Hang on... doesn't CV1, and therefore channel 1, produce the same thing? Yes it does, so there's no point in having both switches set to 'CV'.

Now, let's return to that 'Signal' position. The DK1 has a built-in sawtooth oscillator and an associated VCA with frequency, 'spread, level and dynamic range controls. This is a godsend because, with the spread set to '10' the oscillator tracks the keyboard in a conventional 1:1 relationship. In other words, you can play the keyboard and, with everything else set up appropriately, you'll hear the notes that you would expect. This is not necessarily the case when you use the keyboard CV channels. This is because the keyboard CV channels enter the VCS3 through two input level controls marked, sensibly enough, Channel 1 and Channel 2. The problem arises because the 1:1 keytracking occurs somewhere between '6' and '7' on the knobs, and the exact position can fluctuate wildly with the oscillators' temperature, the time of day, and the FTSE100 index. This makes it very tricky to use the VCS3's internal oscillators for correctly pitched melodies. Every time you play the thing, and even after an hour of 'warming up'm you are constantly trimming the tuning and scaling the Channels.

Furthermore, the VCS3 doesn't confirm to either 1V/octave or Hz/V standards used by every other manufacturer, before and after. It uses internal voltages of 0.32V/octave for oscillators 1 and 2, 0.26V/octave for oscillator 3, and 0.20V/octave for the self-oscillating filter. However, because there are CV amplifiers on the internal module inputs, you need to double these figures to 0.64V/octave, 0.52V/octave and 0.40V/octave respectively for external CV sources. Argghhh!!!!

Likewise, the usual 10V peak-to-peak signal levels are eschewed in favour of 3V, 4V and 6V for the oscillators (depending on waveform), 5V for the filter, 3V for the noise generator... and so on. There was nothing about the VCS3 that we would now regard as conventional.

You might think that this is enough of the VCS3's and DK1's oddities, but you would be mistaken. This is because yet discussed its most notable characteristic: the patch matrix.

ENTER THE MATRIX
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The most important thing to note here is that the VCS3 will remain forever silent unless you stick some pins into the matrix. This is because none of the devices described are connected to eachother unless you use the matrix to determine which signal goes where. Fortunately, the 16x16 matrix allows you to connect any of the VCS3's modules to eachother. For example, let's say that you want to direct the output of oscillator 1 to output channel 1. Since the signal generated by oscillator 1 emerges from the list of sources in row 3, and the input to channel 1 is column A, you simple stick a patch pin in position A3, and the connection is made. Of course, this doesnæt preclude you from sticking more pins in row 3, and yet more in column A, so patches can become very complex, very quickly. Indeed, you can stick 256 pins into all 256 available sockets, but i doubt that it would create a sound. Also, you must remember that, at this point, you have only made a set of connections between modules. Whether you hear a sound, or whether it's a useable one, still depends on the positions on the front panel controls.

Unfortunately, there are three problems with the matrix. The first two are simple to avoid: if mistreated it can become unreliable; and it's very expensive to replace. The third is more fundamental...

The matrix is not "buffered", and this means that, every time you insert a pin into an existing patch, the actions of other patch connections will change to some degree. Let's suppose that you've spent an hour creating a complex patch and getting every knob exactly as you want it. You the decide that you want to add, say, oscillator 2 to the filter input. You insert the appropriate pin - and everything else changes. As you can imagine, this is infuriating.

Now let's turn to the patch pins themselves. These are not simple metal connectors that short between the row and column rails. They are resistors, and there are three types of these in common use. White ones (with a resistance of 2.7kOhm) are the most common, and you can use them for almost anything. However, because the resistors in the pins have a wide (5%) tolerance, they are not suitable for some jobs. In particular, two white pins inserted into I8 and J8 (CV Channel A connected to the pitch CV inputs of VCO1 and 2) will often be sufficiently different to make the oscillators track differently. To overcome this, EMS supplied red pins, also 2.7KOhm, but with 2% tolerance. The third of the common pin colours is green. These pins have a higher resistance than the others, thus reducing the amplitude of a signal considerably. Most often, you use these when you want to attenuate a control signal, such as applying a delicate amount of modulation to a pitch CV input.

If you read some of the conversations flying around the Internet, you might be forgiven for thinking that the VCS3 is no more than a glorified effects unit. In part, this is because few casual users have the patience or knowledge to squeeze conventional musical signals from the instrument. But perhaps more significantly, it's because the VCS3 has four 1/4" inputs on the rear panel - two for microphones, two for line level signals - routed to the Channel 1 and Channel 2 rows on the patch matrix. Because the VCS3 is modular, this is a far more powerful arrangement than the signal inputs on pre-patched monosynths, allowing you to use an external signal as an extra module, maybe as an audio source, a CV source, or even a Gate.

There's another reason why the VCS3 is often regarded as a sound mangler. Because its internal oscillators are so unstable, using external signals (such as generated by the DK1) is often the only way that you can play conventional melodies. So, in many ways, the VCS3's status as an "effects generator extraordinaire" is a classic case of making a virtue out of a necessity."

Scroll through these posts for more history on EMS and of course check out the EMS label below for more.

5Pulser Waveshaper by frijitz

"The most effective waveshapers are the radical ones that produce multiple peaks per input cycle. There have been a number of these designed over the years, of course, but most are fairly complicated circuits.

A while back I discovered that the LM3914 LED bar-graph display driver chip can run at very high frequencies -- crisp square pulses well above the audio range! Operation of this chip is quite simple. It is basically a stack of window comparators, which fire one at a time as the input signal increases. The total span of the comparators is set by an external voltage.

From this I figured out how to make an interesting waveshaper that puts out a variable pulse train. The waveshape control voltage changes the span of the comparators, so an input sawtooth leads to a train of pulses from a single square wave up to a train of five pulses in less than half a period as the control voltage is varied. (The more traditional wavefolders use a VCA on the input signal to vary the waveshape.) The circuit is quite simple for what it does -- a dual opamp for the input signal and CV conditioning, the LM3914 and an output opamp summer to combine the pulses."

Click here for more info including the schematic and a sample.

Moog synthesizer collaborator Herbert Deutsch at IMAC

"One of the most radical shifts in music began in 1961 with a hobbyist magazine article on how to build a theremin and a jazz musician from Baldwin named Herbert Deutsch.

The theremin, an electronic device that generates sound using radio frequencies, had been around for a while, but Deutsch found the Electronics World article interesting enough to pick up the issue and follow the instructions. When he couldn't get his gizmo to work, he phoned the article's author, an engineer, who gladly mailed out an easy-to-assemble kit for $49.95.

Two years later, Deutsch spotted the engineer selling his kits at a music trade show upstate in Rochester, and the two fell into conversation. They discussed a relatively recent invention called the Mark II synthesizer, which made music by sucking up rolls of key-punched paper and etching the results with a lathe onto a shellac record. It was intriguing, but you couldn't exactly 'play' the thing like a piano or guitar, or even a theremin.

'Wouldn't it be exciting,' Deutsch told the engineer, if there were smaller synthesizers 'that a performer could own, or a composer could own? Something you could have in your home?'"

The engineer? Bob Moog of course. Title link takes you to the full article.

Formula Filter Array 24

Update: be sure to check out the comments for more. This was actually made by Bob Moog.

Title link takes you to shots, including some of the inside, via this auction.

"This auction is for one vintage Formula Sound Multiple Resonance Filter Array. This is a USA-made fixed filterbank / string filter from the 1970s that was (according to the engraved faceplate) custom made for San Francisco musician and producer Patrick Gleeson. Gleeson made some excellent albums on his own, but was better known as a session musician and producer/engineer who worked with artists as diverse and influential as Herbie Hancock and Devo. Though this model was advertised by Formula Sound in some magazines back in the 70s (see picture), this is the only actual unit I have ever seen or heard of. Since the faceplate says it was custom made for Gleeson, I believe it is the only one in existence. In theory it is similar to Moog String Filter but with greatly expanded and more tweakable facilities, but generally it excels at allowing you to electronically simulate the natural resonances of an acoustic chamber (like a violin or other stringed instrument).
This is also presumably somewhat of an inspiration for the Moog MURF pedal, as they seem to have taken the name from this unit (MURF stands for MUltiple Resonance Filter). Unit runs on 110V voltage and comes with a standard IEC power cord.

This piece is generally in very good cosmetic and functional condition, but has a few warts that I will be more explicit about in the following paragraph. All of the functions should be fairly self-explanatory... a mono signal goes to the input of the unit and is fed through 24 steep bandpass filters at various fixed frequencies, each of which can be assigned to one or both of the output channels via bus switches on the front panel. When all the sliders are down the unit is fully attenuated (silent).... as various frequency sliders are raised, that frequency becomes audible. There is a resonance shift rotary switch that allows you to change the overall harmonic tone of the selected frequencies and a drive knob which seems to have a compressor circuit built-in and sounds more like a tone control than a harmonic clipper.
In addition, there is a rotary switch that selects the overall mode---bypass (dry signal only), direct (unit engaged, frequencies sent directly to selected output bus), x-fade and x-pan (both similar in theory but different sounding). There are also 1/4" jacks for CV (control voltage) access so that you can integrate it into your modular system... one is a VCA input jack and the other is a modulation output jack that allows you to send the internal modulation LFO out to external equipment for coordinating sweep times. This is a very full featured unit that allows you to radically alter a sound, though it sounds very different and in a lot of ways a lot less radical than a standard lowpass filter.

Everything generally works as expected with a few exceptions, so I'll be pretty explicit here about everything that isn't quite perfect.
---The Drive pot is very scratchy.
---The Resonance Shift rotary switch is very loud and emits a loud thump through the outputs when switching, though this seems to be more by design than by a defective switch.
---The output Bus Selector switch for the 372 Hz frequency is wobbly and doesn't click into place like the others but it selects the output bus just fine.
---In Direct mode, in which is acts as a standard fixed filter bank, the B output bus is noticably quieter (about 15 db or so) than the A output when all frequencies are assigned to both buses. The overall volume difference, however, seems to depend on the drive level, input level and resonance shift amount. At certain settings the output levels are much closer to each other, though. I overcame this by running the 2 outputs into different hard-panned mono channels on my mixer and using the input gain pot to make up the difference.
---In X-fade mode it is the same as Direct mode---one channel is louder than the other. This is very noticable when using the 2 hard-panned mixer channel trick that is described above.
---In X-pan mode the output channels are pretty much equal volume and this mode sounds very similar to the X-fade mode, so I just used this mode instead.
---The front panels is very clean but there are numerous scratches and wear on the top, bottom and sides of the unit. There are some small paint marks that someone added to the selector switches and on one of the frequency slider caps.

This thing is built like a tank. All of the frequency sliders have very attractive machined aluminum tips. It does have some wear, but looks very good both inside and out, especially for a 30-plus year old unit. I've owned it for close to 10 years and I just had it serviced by analog guru Phil Cirocco in fall 2006 to fix a dead output channel. Though I don't have any schematics for the unit, any competent tech should be able to service it as the filter cards are modular (12, with 2 frequencies per channel) and all of the other stuff (VCAs, etc) are on breadboards and the circuits are clear and easily traceable. As you can see by the high quality parts and tons of circuitry, building something like this at today's prices would cost many, many thousands of dollars."

Buchla 259 and 261e

The following notes comparing the original Buchla 259 and the new 261e Complex Waveform Generators came in on the Buchla list via Ezra Buchla, Don Buchla's son. Note the reference to the 258 Dual Oscillator.

"the waveshaping circuits of the 261e and the old 259 are very very very close. they "sound the same." except that the old one is indeed hotter, and the driving sine wave is not quite as clean or as stable in pitch.

to me, the functional difference is in the mod osc section. there are tradeoffs. the 259 has nice smooth cv output and you can push it to very low frequencies with cv input. this is good. the 261e has an additional, quite radical waveshaping circuit on the mod osc itself, which allows you to crossfade between sine, square, narrow square and a kindof funky sinusoidal trapezoid. this is good too. listen to the phase locked mod osc audio output! that is not the same, at all.

phase lock behaves differently. there are more possible behaviors in the 261e, as the process can receive certain information from software-land. and these again can come out as very interestingly close spaced chaotic orbits.

experiment with frequency modulation + pitch tracking + phase lock for maximally intricate orbit-space!

we will not do a 259 clone anytime soon. oh well.

i do luv me a 258. now THAT's buildable. of course maybe not by me, just at the moment... i am busy!

-eb"