Shadows: A Brief Oral History of Disco Lighting

"With different colored lamps behind the same Perspex panel, it would appear to change color."
by Tan Lin

In 2004, I was asked to write an article on disco for Criticism. I was interested in disco’s relation to Warhol’s Shadow Paintings, a 102 panel work that Warhol regarded as a single painting linked to disco: “Someone asked me if they were art and I said no. You see, the opening party had disco. I guess that makes them disco décor.” By the late 70s, disco and CRT would prove pivotal in clearing the way for the Shadows’ systemic medial and discursive shifts away from cinema, photography and painting and towards the ur-digital realms of TV and computing. Such a movement would effectively transfer aesthetic practices away from news and advertising and towards an augmented communications/ entertainment regime that included disco; under its auspices Warhol carried out a number of radical experiments with specific medial supports: the book (as diary, history, happening, novel, photo scrapbook, gossip mags, philosophy, etc.); the magazine; as well as the on-goingness of the television medium in such genres as talk show and daytime soaps. Warhol’s interest in disco is thoroughly in keeping with a longstanding interest in a range of technological devices: Bolex, tape recorder, Portapak, Auricon sound camera, Polaroid, helium balloon, happening, where Warhol’s interest lay not in the gadgets themselves but in their ability to alter prior medium logics. 

As a part of my research I contacted Kevin Hopcroft via his web-site Premier Solutions. Hopcroft founded New Junktion Discotheques in Nottingham in the late ‘60s and created innovative disco lighting and other products under the NJD brand, as well as for other companies. He was chairman of the Professional Lighting and Sound Association. He currently heads Premier Solutions, a distribution company he founded in 2002. Kevin has worked as a d.j, as well as an actor, compere, comedian, stage dancer, and lighting and equipment designer.

Editors Note: Disco as an Operating System  was published in 2008. Tan Lin’s other disco related works can be found here and here

Disco Ball

What were the major developments in disco lighting in the US from 1975-8?
The most significant change in disco lighting during this period was the change from flashing lights in time with music to the use of the Pinspot lamp. This lamp was originally designed as a tractor headlight, but it had a particular property that attracted the disco industry- it had a very narrow beam. This beam effect was used to great effect with fog machines. The combination of a narrow beam of light passing through fog gave the beam of light a 3D effect. 
What was disco lighting like before?
Previously disco lighting either illuminated a particular area with color or was used in a traffic light effect, with the audience looking directly at the light bulb. With the introduction of fog, you could see the whole beam of light from its source to its destination. Lighting designers soon hooked onto this 3D property and started to create "light curtains."
What exactly is a light curtain?
A light curtain is created by fitting multiple narrow beam spotlights very close together and pointing them directly downward towards the floor. This was usually done around the edge of the dance floor, making the dancers look as though they were dancing behind a curtain of light.
But this could only happen with a fog machine?
By adding millions of molecules of fog fluid to the atmosphere, you created what was effectively millions of tiny projection screens floating in the air. When a beam of light hits them they illuminate the air and you are able to see the whole beam from its source to its destination, like a solid 3D object.  If the fog was not used, all you would see would be a series of colored spots on the floor.

Curtain of Light with Fog, Pinspot Lighting & Sequencer

When were smoke machines introduced? 
Smoke machines were introduced in the second half of the 70's. These originally came from the US and the first ones were actually crop sprayers. The main problem with these machines was that they were made of plastic and if the thermostat failed the whole machine melted, which many did. It wasn't long before other companies got into manufacturing smoke machines and they become more and more reliable and are now used commonly in most clubs.
What is a light sequencer?
A light sequencer turns lamps on and off in a predetermined order. The most common sequence was four channel: 4 different lights turning on and off in a rotating sequence. The actual step in the sequence was triggered by a bass beat from the music. When the sequence is activated the eye follows the illuminated lamps- the visual effect is of a light running down a chain. 
How were sequencers in the late 70's engineered? 
The loudspeaker output was connected to the lighting controller that filtered the incoming signal.  Only bass frequencies would trigger the original analog electronics. Early lighting controllers were so crude that if you connected the two speaker wires up in reverse, they would blow up your amplifier. Later models had amplifier protection. 
What were the earliest sequencers like?
The origins of the sequencer are really interesting and somewhat quaint!  The most common was a thing called a commutator. These were originally activated by the old telephones with finger dials on them. The motors would turn and activate different lights in the sequence from the phone.  I saw quite a few discos in the late 60's that used ex-telephone company commutators. I even saw one enterprising DJ use and old gramophone with pegs stuck to the rotating turntable, which activated contacts as it turned. 

3 Channel Analog Sequencer

What was the technological shift that made the analog sequencers?
This came about as soon as simple silicon chips became available. This happened in the late 70’s, I believe. As you know, all digital devices count numbers. Once this was available it was easy to make a sequencer that could count 1, 2, 3, 4 and use that count to activate lights in order. 
What is a thyristor?
Sound sources would be divided into three frequency ranges: bass, middle and treble. When the circuit sensed a note in one of the three ranges, it would trigger a device called a thyristor that would connect mains power to the lighting circuit. Each output thyristor operated one of the three output channels to create a three channel controller. The big disadvantage with these products was that the sound source was derived directly from the speaker output of your amplifier- if you connected the two speaker wires the wrong way around, the lighting control board would self destruct and take your amplifier with it!
How was the design modified? 
Thyristors were soon replaced by the more reliable triacs, which are still used. Isolated sound inputs were also introduced using small transformers, so that they did not self destruct or damage the amplifiers. Pretty soon it was found that four channels looked more effective than three and an extra output channel was added. This was called a "Four Channel Sequencer" or a "Four Channel Sound Chaser." 

4 Channel Sequencer

What else did the silicon chips allow?
These first silicone chips enabled the sequencer to do more than just count 1-2-3-4. Manufacturers were now able to make the four channel sequencer do "patterns." For example: chasing in pairs 1-2 -2-3--3-4-4-1-1-2, etc. This effect created a chase sequence where the eye saw the lamp that was not lit as a moving object. A chip called an "opto-isolator" was also introduced, which connected the sound to the unit via a light source- an LED. The LED was lit by the sound, transmitting its light to a receiver that collected the pulses and transferred them to the lighting controller. The item itself was a very small device- you couldn't actually see what happened inside it. This now meant that there was no physical connection between the amplifier and the lighting controller. 
Was this still analog? 
Yes. Things really only started to make large advances when the microprocessor was introduced. At this point you were no longer limited to the number of channels or patterns you could have.
Where was the light sequencer invented?
To my knowledge, the light sequencer was a UK invention. It was originally released by NJD in the UK, but did not penetrate the US market until a UK company called Pulsar (who are still trading) made their own version that was exported to the states. I would guess that the US got the sequencer in about 1974-1975.
Who invented the light sequencer?
The first light chaser or sequencer that I saw was invented by a man called Brian Binns. He later joined NJD as technical director. When I first saw it, he was working on the principle in his own home workshop and he called it "rota-sound." His idea was to put one channel of light at each corner of the dance floor and point them all into the center of the floor. By sequencing the lights around the floor at north, east, south, and west, the dancers created shadows that moved around them and the floor as the light hit them from different directions. It was very effective, but Mr. Binns never put this system into production. I believe that a company called Zero 88 in the UK were the first to make a commercial version. 

Contemporary Light Sequencer

Was it patented?
As far as I know there was never a patent put on this system as sequencing lights had been used for some time by sign manufacturers. The disco designers simply improved this by using solid state electronics and sound activation to bring it up to date.
So the first light sequencers were designed with shadows in mind?
Yes. The four corners of the dance floor were illuminated on and off in turn, throwing the shadows in different directions. 
If I understand this correctly, when dancing, you would be, as it were, "surrounded" by your shadow from all sorts of different directions. And this was the intended effect? It sounds disorienting.
Yes. That was the desired effect and yes, it was disorientating to some extent, but so is alcohol. In a club atmosphere surreal experiences were the order of the day.
When was the flower effect implemented? 
I am guessing around 1985. This was an Italian invention and used a small projector lamp placed immediately behind the lens. There was a small plate behind the lamp, reflecting the light back inside the product. This light hit a dish with multiple mirrors stuck to it, which reflected a beam of light off each mirror back towards the lens. The multiple images then passed through the lens where it was focused and projected out into the audience. The dish was then rotated using a sound activated circuit that moved the dish backwards and forwards in time with the music. The first of these was very expensive and only the largest clubs could afford to use them. They are now quite possibly the cheapest effect available but still an excellent atmosphere creator.

Flower Effect Demo

Was this mode of sound activation different from sound activation systems circa 1978? 
Yes. Prior to this disco lighting was basically lamps being switched on and off in different patterns activated by music. The flower effect  gave you multiple beams of colored light that, instead of being turned on and off, moved around or across the dance floor synchronized to music.
In the late 70’s how were colored lights used?
Before Pinspot, colored light was used in different ways. The most common way was to fit colored floodlights into a ceiling and then flash them to music, so that the dance floor changed color in time with the music. Another common use for colored light was "back illumination." This involved using Plexiglass and shining the light through it. With different colored lamps behind the same Perspex panel, it would appear to change color. The most well known example of this is the dance floor used in the film Saturday Night Fever. These dance floors are now becoming very popular again, but are now illuminated with LEDs. The other use of colored lamps was to use multiple lamps to form sequencing patterns. These became very elaborate and some ceiling displays used literally hundreds of light bulbs to create moving displays and were quite often wired in a "matrix" allowing the display to expand outwards in circles or rotate as spokes around a center point.
What would these sequence patterns look like?
The most common sequencing patterns were an imploding or exploding effect created by concentric circles of lamps. 
What kinds of colors were used?
Mostly very solid colors: red , blue, green, amber and magenta. 

LED Dancefloor

From Sex Magazine #3 Spring 2013
Labelled Technology