Allen TC-4 Project

[Silken Path]

Greetings, fellow travelers. I have obtained what appears to be a 1959 Allen TC-4 that was MIDIfied by another forum member about ten years ago. I would like to investigate bringing it back to the way it was, and if that is not possible or advisable or affordable, looki at updating it for a Hauptwerk platform using modern hardware with the multitude of high-quality switches and tabs it has.

Here's the first picture. That's it sitting in my garage on a one-ton lift table that I purchased at Harbor Freight. Next I'll get some pictures of it from the back to hopefully find out what's missing and what's still installed. (One device looks sort of like a music box player - I suspect that's a mechanical celeste, as the organ has separate switches for each manual.)

The pedal board that came with it is intact and in very good mechanical condition, although it would benefit from cleaning and refinishing. It's also pretty heavy.

All of the keys on the organ pop back up and have a fairly firm, reassuring feel to them. The casing finish is rough with some mildew spots on the left side (probably from sitting near a window in the south) and a few scratches, dents, and paint speckles.

The tambour top was a booger to push/pull open even with the top up. Generous rubbing of the slots with ivory soap helped immensely.

The pedals look like they're cast metal. I'm going to have to get out of a home organ mindset (Hammond, Conn, Rodgers by Roland) to deal with this monster. :)

[myorgan]

I grew up playing an Allen TC-4S at my home church. Alas, I don't know anything about the innards, though. Best with your restoration.

Michael

[toodles]

A picture of the back of the console opened up will tell us quite a bit about its condition electrically.

The TC-4 was a transistorized organ with usually 4 sets of oscillators: unit flute, unit diapason, unit reed (trumpet or regal) and an optional short set of celeste oscillators. Keying was done by a matrix style multiple contact key contact system with one contact for each pitch register of each unit voice keyed. Except the celeste set of oscillators (if present) was keyed in parallel with the diapason.

[Silken Path]

Due to the limited area I have it in for now, it's hard to get a long enough shot to get all the back in, but here's where the MIDI implementation attaches to the terminals at the rear of the lower manual. Each connection represents one snipped wire in the bundle.

And here's the right side showing the unused wires. There are four large cables exiting from a covered area on the floor panel. I thought Mr. Hammond loved transformers. Allen seems to love relays.

So it will probably be much easier to get the MIDI implementation working and then work on the organ's appearance and the operation of various equipment. (I haven't figured out WHERE the swell pedal feeds into the MIDI network, but the object that looked like a music box cylinder and tines to me is obviously the crescendo switch. Pretty elaborate there.)

The tab switches, for example, look heavy-duty. Are they motorized, or do they just snap into position? Are those long switches I see over power supply and preamp connected to the tab switches?

Are service data and schematics for these old Allens out there?

[toodles]

I always hate to see a photo like this where things look like they were thrown together. A conscientious technician would have made the wiring neat and documented what was done. This looks a mess.

Nevertheless, it looks like the tone generation wasn't touched, and just the keying was either tied into or interrupted. If it was just tied into and nothing was cut, then it should just be a matter of removing the MIDI implementation and cleaning things up a bit.

The crescendo pedal system does look like the music box cylinder you describe--as the pedal rotates, it has a shorting bus bar or strip that sequentially grounds or provides positive voltage to tun on stops. This is standard pipe organ design and used in many electronic organs with setterboards--the other approach is a multi-postition rotary switch with no real detents--which is what this arrangement makes, in essence.

The original swell control used a shutter to control the amount of light falling on several photocells, one for each channel. The organ should be 3 channels--flute, diapason, and reed.

The tab switches, judging by the photo in your first posting should be motorized, as this model has a setterboard combination action. If you haven't found the setterboards yet, they are pull out drawers underneath the keydest, one at each side.

Amplifiers would be external to the console, and the output is a lower level signal--more like a microphone output than an audio line-level. Others here can advise you on the amp input requirements--I don't have the specifics.

Official Allen service info is hard to come by, but some here on the forum can probably provide you with some details--at least enough to get you buy.

At its simplest, each note of each voice is an oscillator that is normally off. When a stop tab is pressed an electromagnet moves a set of contacts into place so that when a key is pressed a voltage is provided to the oscillator, which goes to a preamp to sound. The manual contacts are at the back of the keyboards, the pedals relay are mounted separately from the pedals. The pedal contacts might be mounted on the pedalboard itself with a 33-wire cable going back to the console.

[myorgan]

Are service data and schematics for these old Allens out there?

There's an Allen Analog Service Manual on *Bay right now. Too much, IMHO, but they appear to be taking offers.

Michael

[Silken Path]

I spent a decade doing aircraft maintenance, and this isn't my idea of organization, either. Ah - "Setterboard." Yep - found the drawers full of switches. How complicated. - I'll look more at the wiring and see if I can find enough wires to reach the terminals, and then I'll figure out where they GO to. Having to activate a relay each time a key is pressed sounds like a lot of activity (and failure points). I imagine it can sound clickety-clack in there... The lower manual has a 1959 date on the bottom of it.

The pedal board looks simpler - the wires were moved to a circuit board but I can get them back and the big wrapped bundle is still there. The pedal assembly is so bulky that some other actuator _could_ have been used instead. It looks like it used finger contacts.

The swell pedal looks like it has four pots on it. I'll look closer.

Thank you, Tootles. You're good to have around. :)

And thank you, too, Michael. I think I've bought from that book store before. (I HOPE I left them a good rating.) I'll keep an eye on it and will make an offer. It's still a dozen days out, but I'd like to have it. I've wondered before if eBay is saving the bookstores or killing them.

[toodles]

I'm sorry if I misled you--there is not a relay for each key. There is a solenoid for each stop, and it really isn't very noisy. It brings a set of contacts into play when the key is pressed. This approach has been used by many pipe organ builders, and the same concept was used by Gulbransen, Wurlitzer, Conn, and others, though some of them used a mechanical coupling rather than a solenoid. Failure points are very rare, in fact.

Each solenoid moves a sliding insulator piece with 61 contact wires mounted in the piece; the solenoid moved this piece very slightly to the right (or left, I'm not sure which); the key itself moves a shorting bar which makes contacts only with those contact wires that have been moved into place by the solenoids. If you raise the stop rail, you'll immediately see the contact system and understand how it works.

The pedals worked a little differently--each stop activated a 32 pole, single throw switch with NO contacts. These were ganged together so a pedal contact only needed to wire into one point; the outputs of the switches went to the oscillators. The pedalboard probably did use finger contacts--very common for organ switching of that era. Later pedalboards used magnetic reed switches for high reliability and for permitting a pedalboard without a connecting cable--the switches being mounted in the console and the magnets mounted on the pedals.

The setterboard is not really complicated at all--it is just full of duplication. Each switch is one bit of memory, so there is one switch for each stop for each piston. With 4 pistons. that 4 switches for each stop. The alternative at the time was a tripper combination action, which is a mechanical memory affair--also called an Austin type combination action. That was complicated!

You can see why electronic organs changed a lot during the decades of the 1960's and 1970's--diodes and transistors took over much of the work of a multitude of switches, and then, of course, IC's took over.

If the organ has 4 pots on it then it probably pre-dates the photocell expression system that Allen used later. The patent for the photocell system was filed in 1960. The MIDI system probably tied into those pots.

[Silken Path]

Thanks again, Tootles.

I'm marveling a bit at the workmanship that went into this thing. The wire-wrapping looks like good quality aviation equipment, while I have some organs that literally use twisty-ties on bent-over nails or similar.

I was surprised to discover that there's an old thread here that describes the MIDI conversion of this organ. Google images actually found it for me. I'll have to find that link again and post it here.

I also made an offer on the service manual.

Those contacts with the sliding rail must be what's showing up in the pictures above the power supply and pre-amp. I see it has a solenoid at the end that tugs the entire part slightly.

Forgive my ignorance, but what is a stop rail? Is that the part that supports the stop switches?

And yes, I AM interested in because it's a slice of history. (I also have 1959 stamped on my bottom.) I've heard a couple of the TCs on YouTube, and they sound sort of massive, but that may be just my imagination. One guy's hearing his TC 3 for the first time in five years.

I have about three hours in the morning to work on the organ each day. Then the sun gets too high and I have to push the stuff I moved out of the way back in and close the garage door. It comes from having too much STUFF.

[toodles]

The contacts you see above the power supply are the solenoid operated pedal stop switches--in organ parlance, these are "switches".

The stop rail is the stopboard--it is also called a stopboard, a nameboard, or a stop bolster, but mostly "bolster" terminology is useed on theatre organs. It is the vertical panel on which the stop tablet mechanisms are mounted.

Allen always made organs of very high mechanical, electrical, and construction quality. By the way, the oscillator sets are on slide out rails, but you probably have to remove a cotter pin to permit this. After that, they are hinged at the front, so the rear swings up and over to expose the bottom of the circuitry for repair.

The TC-4 is very much like a pipe organ with 3 sets of pipes, so it has the same sense of ensemble.

Allen built oscillator organs like the one you have through the early 1970's when they switched their entire line to digital. Rodgers continued to build oscillator based organs until around 1990. The late model Rodgers surpassed the analog oscillator Allen organs in tone quality and capability.

The TC-4 was about an $8,000 to $10,000 organ when new. It was and is a very fine sounding analog organ.

[Silken Path]

Some progress has occurred in the project. First, I twanged my back working on a lawn mower two weeks ago and am just getting back to stooping, lifting, twisting, etc. Getting the organ off the hydraulic lift table and onto furniture doilies was a see-saw affair with a floor jack and lots of 4x4 blocks. The organ only threatened to topple over on me once, and that left me holding it up with both hands and wondering "What next?" Anyway, it's mobile now.

And the bookstore on eBay took my offer on the service manual. Got it in a few days ago. It's in good shape and has perfect wiring diagrams as well as a good theory section. If I'm reading this right, this organ RUNS on 14V, so should be a little safer to work on that some Hammonds 'round here.

I've decided that I want to HEAR this organ (someday). I would also like to have MIDI available on it, but have it switchable for when I want it. (I like to toot, toot in Hauptwerk with drastic amounts of reverb.)

Tomorrow, Lord willing and the creek don't rise, I will rotate this monster and start figuring out what got snipped and HOW I can determine what the connections were before.

I'm impressed with what that pedalboard. It was designed for use, but it's big and heavy.

I haven't found yet where or if the swell and crescendo where connected to the MIDI system. Then again, I'm messing with a lot of organs in HW that don't HAVE any.

One thing that I find encouraging is that the organ was modified JUST to make a MIDI machine. Our previous owner LEFT all the other systems untouched. The organ was the auditorium organ at a college. I thought he said "Rhyman" or "Lyman," but it was probably "Furman" as that's more local to where he was That college has a 34-stop pipe organ now, but one of the connectors on the right of this organ is labeled "stage gyro."

Well, onward and upward. :)

[Larrytow]

One thing that I find encouraging is that the organ was modified JUST to make a MIDI machine. Our previous owner LEFT all the other systems untouched. The organ was the auditorium organ at a college. I thought he said "Rhyman" or "Lyman," but it was probably "Furman" as that's more local to where he was That college has a 34-stop pipe organ now, but one of the connectors on the right of this organ is labeled "stage gyro."

Well, onward and upward. :)

I'm a former owner of a TC-4, and yes indeed it is a really nice sounding organ when working well. My particular instrument had the main amplifiers ( tube amps ! ) in the bottom of the two Gyro speaker cabinets, not in the console. I'm guessing that you did not get the Gyrophonic Projector speakers with yours ? Those have the speakers mounted on a rotating baffle, and make the sound more animated. That is what the sideways lever switches above the Swell manual are there to control.

I have always thought that my TC-4 console was the finest one I have ever owned. The one I had still had the tag hanging inside that said "made from Genuine American Walnut " . I think it was solid walnut - not just veneer over other hardwood. My at home church organ is now an ADC6000, and while that is a nice console too, it is not quite as nice as the TC-4 was. And while I think that Allen still builds the nicest electronic consoles in the industry, you can really tell that they have gotten just a bit more economical in how they build them.

Another thing I appreciated about the TC-4 was the keyboards - they were really nice to play. They just had a feel I like I guess. It's kinda hard to quantify it more than that.

I did add Nanoverbs to mine, and as I recall that job, I'm sure that mine did not have the optical expression system either, since I had no issue with the signal levels going to the amps after the reverbs. Mine was a 1959 model as well.

I sold mine after I got the ADC 3 manual, and it was in fine condition yet. One has room for only so many organs after all !

I'm pretty sure that there is a Rhyman auditorium at a college somewhere, as I recall hearing / seeing that name before. Something in the back of my mind is saying it is in Ohio though, not really near you. A google search should find it easily enough. That way you can have have some idea of the provenance of your instrument.

[Silken Path]

Thank you, Larry. It's good to get input form owners and players that have experience with this model. (I've never heard one of these before, but there's a guy on YouTube that posted his TC-3 finally making sounds after five years. It sounds terrible through the speaker he has on top, but he's a happy clam.)

There's a "Ryman auditorium" in sin city (Nashville) where the Grand Ole Opry either is or was.

I understand about the keyboards - I haven't played it yet - but they are heavier and more linear-feeling than the plastic wonders I have. They are also individually adjustable for height and tension, and they have guide pins to make them go down straight. Wow.

Nope, I didn't get the gyro or the bass speaker with it. It appears to have three output cables going into the box on the bottom. I hope to find one cheap with the speakers and then I'll have a parts horse as well. (Or I can pick which organ will require less work to get going.)

This organ case is well worn, but intact. The previous owner had a troop of (very polite) kids, and the organ got some routine wear and tear. Lovely it's not. :)

[Silken Path]

Today I got a started on separating out the wire tangle and tracing the big wires on the bottom. I found that there are three substantial multi-conductor cables that aren't connected to anything. They have ring terminals on one end and bare wires on the other. I think these went to the projector cabinets. Three others end in 1/4-inch plugs and appear to be audio outputs. They may have gone to rack amps, since this was a originally a big installation. Those three originate in a covered box on the floor of the organ.

I also spent an hour or so untangling the snipped black, brown, yellow, and white wires in the bundle. According to the block diagram, the swell, great, and pedal keys all go to the slide couplers before going to the generators. These wires all appear to have been unsoldered from the manual terminal studs.

My next step seems to be to unsolder the ribbon cables from the terminal studs and figure out where all these wires are supposed to go. I'll start that this afternoon if I get some free time.

[Silken Path]

This may be trouble. I take it that all three wires should go to each post?