Legacy Systems: Grey Box vs Discrete
Have you been there? You've been in conversation with a church for a while now, through 5 fund raising campaigns, 3 different boards, a change in organist, and an ongoing debate about whether they should do a full restoration of the organ, just repair what absolutely must be done, or scrap the whole thing and switch to keyboards and guitars, but they are finally ready to sign contracts and write some cheques. Now you have some decisions to make. What is the most cost effective system for you to use in terms of hardware and labour costs?
Classic has two basic types of systems, our new Maestro System which will be discussed in another post, and the Legacy System, which Classic has been building for 25 years.
The Legacy System is built around a Console Control Computer (CCC), this computer does most of the processing for the organ including keying, coupling, stops, combination action, memory levels, MIDI, and many optional features. The CCC outputs data to whatever combination of things actually produces the sound, this may be pipes using our Pipe Console Computer (PCC), MIDI sound modules such as the CM-100, Hauptwerk, or a tone generator like Walker.
How you wire up your stops, manuals, and pistons to our system can make a big difference in your costs. We have 2 basic ways of wiring a Legacy System, discrete boards or grey boxes (packaged) for the console and chamber(s).
With a discrete system we send the individual circuit boards such as the CCC, Stop Action Magnet Driver Board (SAMDB), and Pipe Diver Boards (PDB), you the builder, do all the interconnection wiring. Using discrete boards will save you on hardware costs, however this does take more skill on the part of the builder. The possibility of errors in wiring will go up with a discrete system, this will in turn cost you in terms of time and labour. If you are highly experienced with Classic systems, or you are a small builder with no staff to pay, this may not be an issue.
In a grey box system all the circuit boards come mounted and pre-wired inside a grey metal box. The front of the box is a large pin panel which everything gets wired into, one pin per item. On/Off coils may be positive or negative common, you need to specify this at the time of ordering. The packaged system does cost more, but is easier to wire, thus will typically save time in labour costs.
These systems may be mixed and matched, for example you can have a grey box in the console and discrete boards in the pipe chamber.
There are a couple other things that may influence your decision between a discrete system and a grey box. A discrete system in the console allows the builder to matrix wire keyboards, stops, and pistons straight into the computer, thus eliminating the cost of switch input boards, a grey box system must be parallel wired. If you are rebuilding an old system and reusing the tilt tabs, mauals etc, you will probably have to parallel wire. If you are going to matrix wire keyboards and stops, make sure you have a diode in series with the switch, this should be checked right at the beginning. If you are ordering tabs from somewhere like Syndyne or Klann, you can specify that you need a diode for a Classic system. If you are using Classic's Lighted Rocker Tabs, I wouldn't recommend using the grey box system. The LRT's can not be parallel wired, and they don't have On/Off coils making half the grey box unnecessary. Optical keyboard wiring (manuals only) can be used for either a discrete or grey box system.
There are so many small choices and parts to think about when building an organ I hope this article give you some insight in order to make some wise choices.