Compton console conversion
We originally designed our organ products for ourselves, for use in our Compton console. If they work well for us, we thought, then perhaps other people will be interested in them too. This might ignore the formal rules of marketing, but it is how Alec Issigonis designed cars and how Steve Jobs designed computers!
We didn't want the console to look like the inside of a telephone exchange by the time we had finished. Even telephone exchanges don't look like the insides of telephone exchanges nowadays. We wanted to use a sensible minimum number of boards, based on a small number of standard designs. Furthermore, we wanted most of the boards to be situated close to the things that they were controlling, to keep trunk cabling as short as possible. Lastly, we wanted to avoid proprietary data connections between boards wherever practicable and instead use MIDI throughout. MIDI is a slow communications protocol by today's standards, but it is sufficiently fast for its task, it is a universally recognised standard, and (importantly in this environment) it has good noise immunity.
We didn't want the console to look like the inside of a telephone exchange by the time we had finished. Even telephone exchanges don't look like the insides of telephone exchanges nowadays. We wanted to use a sensible minimum number of boards, based on a small number of standard designs. Furthermore, we wanted most of the boards to be situated close to the things that they were controlling, to keep trunk cabling as short as possible. Lastly, we wanted to avoid proprietary data connections between boards wherever practicable and instead use MIDI throughout. MIDI is a slow communications protocol by today's standards, but it is sufficiently fast for its task, it is a universally recognised standard, and (importantly in this environment) it has good noise immunity.
The console
Our console was originally installed in 1930 in the Gaumont, Smethwick. Pipework from this organ is still in use at the Penistone Paramount and Pipes in the Peaks.
The console has three manuals with second touch on Accompaniment. Each manual has six double-touch combination pistons. There is a 32-note pedalboard, also with second touch, 15 toe pistons and three expression pedals. There are 65 stops on the lower sweep, 62 on the upper sweep, and 22 stops on the back rail. We are using Reisner Stop Action Magnets (SAMs) on the back rail and original Compton ones on the sweeps. We have replicated the unique Compton second touch cancel feature. To the best of our knowledge, this is currently the only virtual organ so equipped.
In total our console has some:
516 digital inputs (keys, combination pistons and stop switches, including second touch)
3 analogue inputs (expression pedals)
298 digital outputs (stop magnets)
Of itself, converting these inputs and outputs to and from MIDI is not a major challenge: there are several products available which will do the job. The challenge is to do so without - as mentioned above - ending up with a small telephone exchange.
The console has three manuals with second touch on Accompaniment. Each manual has six double-touch combination pistons. There is a 32-note pedalboard, also with second touch, 15 toe pistons and three expression pedals. There are 65 stops on the lower sweep, 62 on the upper sweep, and 22 stops on the back rail. We are using Reisner Stop Action Magnets (SAMs) on the back rail and original Compton ones on the sweeps. We have replicated the unique Compton second touch cancel feature. To the best of our knowledge, this is currently the only virtual organ so equipped.
In total our console has some:
516 digital inputs (keys, combination pistons and stop switches, including second touch)
3 analogue inputs (expression pedals)
298 digital outputs (stop magnets)
Of itself, converting these inputs and outputs to and from MIDI is not a major challenge: there are several products available which will do the job. The challenge is to do so without - as mentioned above - ending up with a small telephone exchange.
Modular design
We wanted to keep the console electronics modular so far as possible, with a minimum of connections between the different modules. This greatly simplifies assembly and subsequent maintenance. Each of the following assemblies can be removed without affecting anything else:
Assembly
Solo (top) manual, with combination pistons underneath Great (middle) manual, with pistons Accompaniment (bottom) manual, with second touch and pistons Toe board with toe pistons and expression pedals Pedalboard (1st and 2nd touch) Upper stop sweep Lower stop sweep Back rail stops |
MIDI controls
73 digital inputs 73 digital inputs 134 digital inputs 15 digital inputs, 3 analogue inputs 64 digital inputs 66 digital inputs, 124 digital outputs 69 digital inputs, 130 digital outputs 22 digital inputs, 44 digital outputs |
Connections
26-way ribbon cable to encoder 26-way ribbon cable 26-way ribbon cable 26-way ribbon cable 26-way ribbon cable MIDI in and out, DC power MIDI in and out, DC power MIDI in and out, DC power |
Keyboards
Although MIDI keyboard encoders are available from several sources, we could not find any which also encoded combination pistons. Since combination pistons are almost invariably directly underneath a keyboard, it seemed logical that they should be encoded by the same circuit board.
The next decision was whether to connect the key switches in a bus configuration, with a wire from the encoder to each of the 61 keys and a common return, or a matrix. We offer both bus-based and matrix-based encoders (MIPC-1A and MK-03 respectively). A matrix configuration requires less circuitry and less space, but it requires a diode to be connected in series with each switch, and is more time-consuming to assemble.
On our console, we are using a matrix approach in view of the very large number of inputs, when combination pistons and second touch are included. Solo and Great are encoded by a single MK-03, operating in mode 1 (MK-03 modes are explained in the instructions). A second MK-03 is used in mode 2 to encode the Accompaniment manual, including second touch.
The Accompaniment manual best illustrates the advantage of the matrix configuration. A single 26-way ribbon cable goes to 61 first touch contacts, 61 second touch contacts and 12 combination pistons. In a bus configuration, 135 lines would be required including return.
The next decision was whether to connect the key switches in a bus configuration, with a wire from the encoder to each of the 61 keys and a common return, or a matrix. We offer both bus-based and matrix-based encoders (MIPC-1A and MK-03 respectively). A matrix configuration requires less circuitry and less space, but it requires a diode to be connected in series with each switch, and is more time-consuming to assemble.
On our console, we are using a matrix approach in view of the very large number of inputs, when combination pistons and second touch are included. Solo and Great are encoded by a single MK-03, operating in mode 1 (MK-03 modes are explained in the instructions). A second MK-03 is used in mode 2 to encode the Accompaniment manual, including second touch.
The Accompaniment manual best illustrates the advantage of the matrix configuration. A single 26-way ribbon cable goes to 61 first touch contacts, 61 second touch contacts and 12 combination pistons. In a bus configuration, 135 lines would be required including return.
Pedals and toe pistons
A third MK-03 is used in mode 3 to encode the 32-note double-touch pedalboard, the 15 toe pistons and the three expression pedals. This board is mounted low in the console, just to the left of the pedalboard, and the only connections to it are MIDI out and 12v DC power.
Even though the expression pedals were originally digital, with a diagonal wiper and 16 contacts for 16 swell shades, we considered it easier to convert them to an analogue action using a long linear potentiometer.
Even though the expression pedals were originally digital, with a diagonal wiper and 16 contacts for 16 swell shades, we considered it easier to convert them to an analogue action using a long linear potentiometer.
Stops
The stops are split into three modules: the upper and lower sweeps, and the back rail.
The back rail stops are encoded and driven by an IDC-48.
The two sweeps are nearly identical. On each, there is one MIPC-1A to encode the switch movements, including the second touch cancel contacts, two DC-96's, each of which drives the solenoids for up to 36 stops (allowing a total of up to 72 stops per sweep). The boards have been programmed with custom code and are connected to each other via a proprietary serial protocol. We can advise if you are interested in commissioning similar custom programming for your own MIDI boards.
The back rail stops are encoded and driven by an IDC-48.
The two sweeps are nearly identical. On each, there is one MIPC-1A to encode the switch movements, including the second touch cancel contacts, two DC-96's, each of which drives the solenoids for up to 36 stops (allowing a total of up to 72 stops per sweep). The boards have been programmed with custom code and are connected to each other via a proprietary serial protocol. We can advise if you are interested in commissioning similar custom programming for your own MIDI boards.
Here is an example of second touch cancel in action:
Summary
Our console contains the following boards:
Solo and great manuals: 1 x MK-03
Accompaniment manual: 1 x MK-03
Pedalboard: 1 x MK-03
Upper stop sweep: 1 x MIPC-1A, 2 x DC-96
Lower stop sweep: 1 x MIPC-1A, 2 x DC-96
Back rail stops: 1 x IDC-48
Total of 10 boards comprising: 3 x MK-03, 2 x MIPC-1A, 4 x DC-96, 1 x IDC-48
For the PC interface, we use an M-Audio MIDIsport 4x4, which has four input channels and four output channels. Solo and Great are connected to MIDI interface A, Accompaniment to B, pedals to C and stops to D.
Solo and great manuals: 1 x MK-03
Accompaniment manual: 1 x MK-03
Pedalboard: 1 x MK-03
Upper stop sweep: 1 x MIPC-1A, 2 x DC-96
Lower stop sweep: 1 x MIPC-1A, 2 x DC-96
Back rail stops: 1 x IDC-48
Total of 10 boards comprising: 3 x MK-03, 2 x MIPC-1A, 4 x DC-96, 1 x IDC-48
For the PC interface, we use an M-Audio MIDIsport 4x4, which has four input channels and four output channels. Solo and Great are connected to MIDI interface A, Accompaniment to B, pedals to C and stops to D.