The Azimuth Coordinator III

[Hatredman]

I'm thinking of building one. I may have to redesign it, because the original circuit has been lost in the night of the ancient aeons.


(Wikimedia Commons)

It's not a true stompbox in the sense that's not an effect for the musical instrument (even if it's operated by a musician), but a contraption to give quadraphonic capabilities, through the PA, to a particular instrument or mix, and used mainly to produce sound effects.

The thing is in fact very simple, with two panning circuits in series, the two pots contolled by a joystick. If you have a PA with four columns, you can position the sound image at any specific place in the room. With the joystick in the central position, the sound output would be equal in all speakers.

As you probably know, there is no Stereo or Quadraphonic or 5.1 concert - all live PA sound is mono, even today. Stereo is relegated to some effetcs, at specific parts of the show, but the mixing in large venues is mono. In smaller venues, at selected houses, the sound technician may (or may not) "open" the mix to stereo, IF the audience is located on the right spot to hear the stereo. But stereo mixes are a PITA to get right (and at concert SPLs the brain gives up trying to "decode" stereo), so in the end everybody mixes FOH sound in mono, except for some sporadic stereo effetcs.

The thing is, these effects are "played" by the operator at the soundboard, with no input from the musician. The Azimuth Coordinator, on the other hand, may be on stage to give musicians some degree of control over these effects. In Pink Floyd's case, Richard Wright was in charge of it.

So that's it: The Azimuth Coordinator. With it, the FOH sound can still be mono (panned to center), but there are four channel strips on the soundboard - each panned to one "collumn" - that receive one of the four outputs of the AZCOO.

I am thinking of designing three versions, one stereo (for the more common two-column PA), one quadraphonic (for a specific - and rare - 4-column PA), and a 5.1 with 5 pan-controlled outputs plus a sub, non-pannable, output. I guess the stereo version will find much use and usefulness in the majority of PA setups.

[Hatredman]

A little background

For one of their first live performances after signing to EMI, called "Games for May", Pink Floyd ordered something to the EMI boffins that would give them control over their quadraphonic PA - a novelty at the time, 1966/67.  Engineer Bernard Speight at Abbey Road Studios ended up building the unit. The Azimuth Co-ordinator was the first panning control for a quadraphonic sound system, at that time a new concept. Pink Floyd became the first band to use it in their early shows.

The original unit was stolen after the first concert in Queen Elizabeth Hall in London, England, the aforementioned Games for May. A second was built for the concert at the Royal Festival Hall in London on 14 April 1969. It had two pan pots and four channels.

You can hear the Azimuth Coordinator in action in the song Cymbalyne. There is a mid-song intermission where footsteps are heard panning from right to left.

[PRR]

I built such a thing for a theater production, but very different technology.

Mount a small lamp in the center of a cake-pan (not shown). Put a tuna-can over it, with a hole in one side, suspended on a shaft through the cakepan lid to a knob. Mount four LDRs around the tuna can.

As the knob turns, each LDR gets light, and drops in value.



Lamp brightness versus load resistors adjusts the general curve, gradual or abrupt.

Some hole trimming is needed to get a smooth transition from NW to NE, etc.

There is not a natural "all" position. (You could make the tuna-can slide up so all LDRs see the lamp.)

The show operator loved it. And I was pleased with simplicity and conservation of scrap cans.

[Hatredman]

Yay, that's awesome, Paul

[Hatredman]

My wife gave me some slack, so I could use pen and paper to draw something. This is a rough block diagram of what's on my mind.

The design is of course not rocket science, but I think the results will be interesting. Two simple panning circuits, mechanically interacting to each other in a joystick assembly.
There are three inputs with three different signal levels/impedances, to accomodate every situation.
The outputs are all ballanced line level, low impedance, because the next equipment in the chain should be the mixing desk/soundboard/whateveryoucallit.

The circuit will have to deal with the fact that only 90 degress (one third) of the potentiometers swing will be available, due to mechanical constraints.

The Stereo version is just an ordinary pan control, but I plan to build two "sub-versions" of it: one to be operated by hand, and the other specific for guitar, in a wha-like enclosure.



The two pots (one of them tandem) should be mounted in a joystick, this way:


You can buy it ready made, or roll your own:
http://www.instructables.com/id/Cheap-working-homemade-arduino-joystick/?ALLSTEPS

[crb3]

If you can handle something with more modest size, All Electronics recently* had joysticks "removed from RC equipment" in their catalog. Two 5K pots, but I suppose you can derive control voltages from those.

* for certain values of "recently"... I last bought from them in 2012.

[Hatredman]

If you can handle something with more modest size, All Electronics recently* had joysticks "removed from RC equipment" in their catalog. Two 5K pots, but I suppose you can derive control voltages from those.

Thanks crb3!
They have this one, which is perfect because the pots were removed, it's just the mechanism:

http://www.allelectronics.com/make-a-store/item/js-10/joystick-mechanism-no-pots-or-springs/1.html

I'll have to import it, though (I'm in Brazil, tax and import procedures here are a nightmare) so I'll have to check if it's feasible or I'll have to resort to make my own.