About the Rodgers Cambridge 220-II
At the end of 2007 I came into possession of a Rodgers Cambridge 220-II electronic organ in pretty good condition. This is a church organ, and in fact came from my parents' church when it was retired from service in November 2007. It was in mostly-working condition at the time (it was removed to make way for a new pipe organ), and I restored it to as close to fully operating condition as I could get it in my time available.
The organ has since moved from my parents' garage to a new home at an organist's in New Jersey. I had secretly hoped to keep the organ and modernize it (and in fact some of the work I did, described in articles to follow, was with that end in mind), but oddly enough my parents didn't want it taking up half the garage indefinitely. Now a real organist has the instrument, and I must admit that's a better place for it. Even if, as a friend told me, that's the first time New Jersy has been called "a better place".
About the instrument
My guess is that the average web surfer doesn't know what a Rodgers Cambridge 220-II is, so here is a short description of the instrument. The organ was built by the Rodgers Organ Company in the late 1970s. The company is still around today, though it is now called Rodgers Instruments and is part of the Roland Corporation. The console contains all the electronics but doesn't make any sound itself -- that is accomplished by six external powered speakers. The console has two 61-key keyboards and a full (32-key) pedalboard. I don't know how stops are usually counted -- the user's manual lists 57 stops, although only 39 of those actually produce sound. The others control couplers and such. There is an expression pedal for the great and swell keyboards as well as a crescendo pedal, which activates progressively more and more stops as it is depressed. (There's also a 'tutti' button that activates almost every stop on the organ. Wheee!) This organ has a 'computer capture system' that provides 25 reprogrammable stop presets. (They stretched the definition of 'computer' a bit there, it's really just some magnetic core memory to store the presets.) (By the way, core memory! I don't think I've ever actually seen core memory used anywhere else.)
I'm not sure how to describe how the organ sounds. It is based on analog oscillators, an old electronic technology with a distinct sound that isn't very much like a pipe organ (especially when compared to modern digital electronic organs). That's not to say it sounds bad, though. Its warm analog sound is distinctive and it sounds quite nice as an instrument in its own right. I don't really have the perspective to judge, (this organ is older than I am, and I wasn't especially interested in electronic organs until I got the opportunity to work on this one) but I'm told that this model is supposed to be one of Rodgers' stronger efforts in the analog realm.
The console is a beautiful piece of work. It is all stained wood and is built solidly -- which makes it incredibly heavy, too. The finish is a bit faded and worn in places after thirty years of service, but there's no real damage anywhere. I suppose a church sanctuary isn't exactly a harsh environment. The console is absolutely packed with electronics. There are three large panels of circuit boards that swing out of the back of the organ, another panel on top that houses the stop preset system, and various other boards and modules mounted around the frame. There must be miles of wires running between them. The electronics take up so much room because they consist entirely of individual components -- although integrated circuits existed at the time the organ was designed, they were still prohibitively expensive. Just the logic for getting the proper oscillator to sound for a given key and stop combination involves rows and rows of circuit cards with thousands of diodes and transistors. What I found amazing (aside from the amount of work that must have gone into assembling all of this) is that it is all accessible and designed to be worked on. It is such a nice contrast with most consumer electronics items, which are made to be thrown away when they break. Here, everything is accessible. Not only do the panels of electronics swing out, but the entire front face rotates up, as does each keyboard. Cover panels are easily removed. And the technical manual includes schematics of everything! Anything that can go wrong, can also be fixed!
One feature of the console I thought really clever is that there is no electrical connection between the pedalboard and the rest of the console. Rather, the end of each pedal has a magnet on it and there is a row of sealed reed switches along the front of the base of the console. When the pedalboard is in place, pushing a pedal down brings its magnet into position to close a corresponding reed switch. So when the pedalboard is removed there aren't any linkages or wires to worry about. Very slick.
The console houses nothing but electronics; all the sound is produced by big external powered speakers. This organ has a total of six of them. Four of them are Rodgers M13-100U speakers that are about 3' x 4' x 9" deep. Each has several 6x9 cones and a tweeter all wired together. The other two speakers are woofers of about the same size. One contains a single 13-inch speaker cone, the other has two. The woofers appear to have the same construction as the others so I assume they were also made by Rodgers, but they have no labels on them. All of the speaker cabinets are unfinished -- in the church they were mounted in a wall with cloth across their fronts. There is also a crazy horn thing that looks like someone chopped the end off a trumpet and stuck it on a tweeter driver. I'm told it was inside the wall with the other speakers but wasn't wired to anything. Seeing all the speakers lined up together is kind of an awesome sight, it reminds me of an old Pink Floyd video (Echoes, from Live at Pompeii, to be specific) with their giant row of speakers and amplifiers stretching off into the distance.
I didn't get a chance to examine the speakers before they were removed from the church, which is too bad because I can't tell how they had been wired to the amps. Some of the amplifiers were driving multiple speakers in parallel and some of the amplifiers were blown. I don't know if the blown amps were the ones driving too many speakers, or if some amps blew and then their speakers were wired to the remaining amps instead. The woofers had crossover networks inside them, but they weren't wired to anything. One speaker was connected through a relay but the relay coil didn't seem to be connected to anything. In any case, it looks like all of the amplifiers had required some repairs over the decades. The organ was suprisingly quiet in my parents' garage -- I think all of the volume levels had been adjusted way down inside the console in an effort to stop burning up amplifiers. I don't know if we were abusing the amplifiers with our speaker setup in the church or if they just weren't as robust a design as the rest of the organ.
