Allen TC3 into TC4 = possible?

[toasterDude]

So I've finally come into possession of a full-sized AGO Allen for use as a home/practice instrument - a TC3. Despite being a little bit appalled at the sheer size of this beast (not to mention the pair of enormous model 100 Gyro cabinets that came with it), I'm excited about the possibilities.

I intend to add MIDI to it, non-destructively, at some point down the line. But until then I just want to enjoy it in all its analogue glory! Now, here's my question... I have access to a significant cache of parts from a couple of the lesser (flutes-only) instruments in Allen's analogue range from the 1960s. Would it be feasible to add ranks of oscillators to the TC3 to improve the instrument even further? This TC3 seems to have come from the period before Allen adopted the "TC-3S" designation to identify the presence of an independent Celeste generator; that is to say, even though it's not marked TC-3S, it appears that it actually does have a Celeste rank of oscillators, given that it has a "Celeste Strings" tab in the General section. So it's essentially a three "rank" organ: Flutes, Diapasons, and Celeste... so my thought is that if I could add another rank of oscillators, I might be able to achieve the tonal possibilities of a TC-4.

Now, I realize the TC-4 is distinct in that its fourth set of oscillators is a dedicated Reed "rank". But I'm wondering if these were a fundamentally different design than the Reed "trunks" which were essentially a frequency drawn off the Flute oscillators, then chopped up by being fed through a diode to yield the more complex waveform. In that case it might be as simple as wiring in another oscillator rank and "tone changer" circuit. Even if not, I'm thinking it still might be possible to adapt a rank of Flute oscillators to achieve a Reed generator.

So what does anyone think? Am I nuts, or is there real potential here? :-)

[circa1949]

Wow, and I thought I was hardcore! I have no doubt it could be done...if you have the time and wherewithal, great. I say this because, ultimately, the keying on those organs is just based on wiring and I believe a mechanical doohickey in the top of the console that engages a bunch of pins...there's no digital code you'd have to crack as in one of the later organs. (For example you could never combine two ADC organs without getting the TDM data line to send a new series of stop selection words, which comes from a custom memory chip. It would take Allen helping you)

I do think the "trunk" approach you talk about was used only in the T15B, not the T12. I had a T15 when I was a kid. Some of the reed sounds (the approach was also used for a so-called principal stop) were not too shabby. I forget what happens if you pushed all those green stops down? Did you just get the tone of the loudest? OTOH I think the TC models just had a fully separate reed rank that was keyed a different volumes for say, oboe versus trumpet. Why the trunk approach was not used on larger models is not something I've been able to figure out, except for the problem of it "stealing" the flute voice it comes from. Still, as I said I don't see any reason you couldn't key them using the a new bunch of wires and pins.

The advanced TC (6 & 7? 7 & 8? and definitely the big custom organ in Dell's video) had some kind of more advanced diode keying, similar to the Rodgers of the day. These allowed more sophisticated combinations of the basic unified ranks.

Here you go: http://www.flickr.com/photos/david_1...in/photostream

[toasterDude]

Thanks for the link! That's a neat brochure.

I think you're right... I've been looking over what service data I have; it sounds like the T-12 (and "Empire" - there's actually one on Ebay right now believe it or not) was a Flutes-only organ. Any other sounds were produced additively by building in other harmonics, like on a Hammond. I play a T15B sometimes, and it has the reed "trunk", which is fine as far as it goes. But the poor little thing is pretty much maxed out on the reed voices, so that you can't add any other stops!

But my understanding was that you didn't get a separate reed "rank" until you got to the TC-4 - hence my original question. Was I wrong though? I haven't had much chance to look around inside this TC-3, so I could be wrong. I think part of the confusion is that Allen seems to have been very flexible about customizing any model in the line. For example, another member on here has said he had a TC-1 with the extra Celeste rank of generators, but princess pedals, and I have heard of (but not seen) models as high as TC-3 having the princess pedals; then on the other hand I just noticed on Ebay there's a T-12 for sale, that has full AGO pedals and even a Crescendo pedal. So there are all kinds of possible combinations out there: including economy models with surprisingly nice features, but also models further up the line that have entry-level features.

anyway thanks again-
Scott

[circa1949]

I think you are correct. You could always play "let's make a deal" LOL. For example a few years ago it was funny to see a mid 1980s MADC Allen in the cheesy 1970s "SciFi" console, as I called it.
Not sure what you mean: But the poor little thing is pretty much maxed out on the reed voices, so that you can't add any other stops!
As I recall, the way it worked was the organ generally behaved like a T12...there was even a clarinet stop on the great that was just 8 + 1 3/5 or whatever that combo would be. On the swell though, you had those 4 or 5 green tab voices. The idea was you could use them as solo voices. What was it...trumpet, oboe, string, diapason? You could still accompany on different notes using the great - with the non-trunked flute rank. The reed trunk only activated for the note(s) you played on the swell. So, it was still an improvement on the T12, however slight. I wouldn't be surprised if the "trunking" approach reappeared in some of the large custom organs. If you needed a solo sound on a 3 manual organ there would really be no point in letting a flute rank sit there doing nothing. Who knows. Would love to have heard the 40 oscillator rank organ at 10th Presbyterian in Philadelphia. Wowzers that must have sounded incredible. One wonders if Allen has recordings of it in their archives that they will never release.

I seem to recall hearing of a TC3 that had a reed generator, but I could be wrong. MarkS used to know more about these organs than anybody else but as we know, people around here come and go! I recall the interesting thing he said about the big advanced TC organs (6&7 I think) was that their stoplists were very similar to the TC4 & TC5, but the way the notes were keyed made everything sound more realistic.

[MarkS]

Huh? (As he rubs the sleep out of his eyes.)

Here goes:

T12 One sine wave flute generator

T15 One sine wave flute generator; a few additional 8' voices on swell derived from generator but fed through a second audio channel--STEREO! One of the tabs (for a string?) had a cryptic, ominous warning about combining stops or playing too many notes. Anyway, the diapason and trumpet were polyphonic.

C1/TC1/C3 Two generators: sine wave flute and diapason, optional celeste on TC1, optional "stopped flute" voicing on TC1

TC3 Same two generators; three additional voices on swell: Geigen 8', Trumpet 8', Oboe 8', derived from flute generator but sent through the diapason audio channel

TC3S (successor to TC3) Two generators: diapason and flute/reed generator (producing two tone qualities of flutes plus reeds at various pitches, divided into two audio channels) plus celeste generator (optional or standard?)

C4/TC4/Classic Three generators: diapason, flute, reed, plus optional celeste

TC5/314 (or was it 312?) Diapason, flute, reed, celeste generators
Some voices appeared at a reduced volume, accomplished with resistors
Expression divided by flues and reeds (Very awkward!!)

TC6 Diapason and flute generators, Swell Flue 8', Swell Celeste, Swell Reed 8" generators; all in a remote rack Swell generators coupled to all divisions at 16', 8' and 4' and were under separate expression and antiphonal control

Basic "Custom" two and three manual: Diapason, Flute, Reed, Celeste generators, all in a remote rack
These had full couplers with the electro-mechanical switching in the console, plus a second set of electro-mechanical switches for the stops, located in the rack; this was very similar to an all-electric action unit pipe organ with full couplers.
Expression divided by flues and reeds. You want an independent swell? Buy more generators! A relatively common specification was for a two manual with seven generators: Swell Flute, Diapason, Reed, Celeste; Great Flute, Diapason, Reed (usually a big Harmonic Trumpet/Bombarde). It must have been very expensive for a two manual organ.

I've never seen an analog Allen with diode or solid-state keying. The switches (relays) may have been standard pipe organ issue from Klann or copies of them. They seem to last forever.

Mark
1957 Allen C3
1984 Allen ADC 720

[circa1949]

Thanks Mark, good to know you are still around. I think I was confused by the "Some voices appeared at a reduced volume, accomplished with resistors" a feature you'd discussed early in relation to the >TC5 organs. I'd just assumed it required diode keying to do something like that. Thanks for clearing it up! I think the Cedar Lane Unitarian custom 2 manual that kicked around the DC area in the used market had that Harmonic Trumpet/Bombarde rank...the badly recorded but stirring Mp3 file of one of the organ's last church performances had an incredible trumpet sound.

Sound like the "trunking" appeared in the TC3! That might explain why I'd once thought those had a separate reed rank. I assume all TC organs had "diapasons become dulciana"?

I found a really good overview of a TC4 on youtube: http://www.youtube.com/watch?v=5FdhOcYpijE

[OrgansR4Me]

Toaster, I'm not a serious enough electronics hobbyist to comment on mods; but I own a later analogue Custom Carousel and it has a very serious trumpet stop. I'm sure this was accomplished by filtering so I would raise the possibility of an easier route to a reedy organ would be found on your voicing boards. With two large gyros I'm certain you have enough "chorus" to hide the missing rank.

[nullogik]

I've uploaded a scanned copy of the Allen TC-3 brochure. Click below for the first page and then use the single blue arrow pointing right to move to the next three pages.

http://www.organforum.com/gallery/di..._display_media

Somewhere I have TC-4 and TC5 brochures/stoplists. I can scan them and upload them if anyone wants them.

Toasterdude, if you want to do serious mods to your TC-3 then I suggest the Allen Technical Service Information Pack for the TC models is worth getting. I think it was only about $50 (it was a few years back that I got mine) and there are plenty of schematics and circuit diagrams. Definitely money well spent.

[circa1949]

Nullo, did you scan those brochures? If you did, great! I'd never noticed the organ brochure gallery on this site. I love how the brochure for one of the smaller MDC organs says it "looks like an organ, sounds like an organ, and plays like an organ". LOL. What's the matter Allen, have something to hide? Those instruments were dogs! "The MDC tone generation is in a class by itself" - yes, arguably, the worst Allen ever had.

[toasterDude]

Apologies for "bump"-ing this thread back to the top, but... here's the kind of thing I'm considering:

http://www.ebay.com/itm/180729918502...84.m1438.l2649

(Ebay item #180729918502)

Upon further investigation, my TC3 definitely has three "ranks": flutes, diapasons, and celeste, with the reed "trunk" drawing off the flute generators. So this leads to two shortcomings, both mentioned before: 1) the corresponding flute tone always sounds along with the reed tone; 2) if you have a stop like "Trumpet" selected, adding other stops makes little difference in the timbre, since "Trumpet" is already calling on so many of the available tonal resources. (for the record, mine doesn't have any green-colored tabs; I think those must've been on the Theater models - ?)

So anyway my thought was just that it might be possible to add a spare rank of generators, such as the one on Ebay, as a dedicated tonal resource for the reed voices. At the very least, this would minimize problem #2 above. But really I was hoping that the additional rank could be reconfigured as identical to the reed rank in a TC-4. So I guess my main question is whether the oscillators themselves would differ, i.e. between a tray of Flute generators and a tray of Reed generators? --I haven't received my technical information packet from Allen yet, to get a peek at the schematics, but intuitively I would think the design would have to be different. So maybe this is a red herring after all...

In any case I appreciate the discussion and additional info... and Nullogik, I too would love to see the scans of the TC4 and TC5 brochures, if you come across them.

[m&m's]

If you decide to buy the generators on ebay, as they are already flute generators, you would want to use the exciting flute-reed generators in your TC3 for reeds only. I do not know what is involved in this, but I am sure others can answer the questions you may have.

I myself had considered a project like this some years ago, when I had a TC4, to make the manuals independent by adding generators from a TC3 or 4 for the Great manual and Pedals, and sometimes wish I had gone ahead with the project. The Allen analog tone generating system sounded a whole lot better than anything digital at that point, and i think that that only Hauptwerk beats it today.

[toodles]

It is feasible to add an additional rank to an Allen analog organ--if there is physical space for it. The reed ranks used the basic sine wave oscillator (same as the flute), passed it through a diode to rectify it and add harmonics, then had a filter for each note. Generic schematics are in "Electronic Organs" by Norman Crowhurst Vol. 2 for the Model 314--basically a TC4 stretched to 3 manuals; the model, 314, came from the number of oscillators I was told.

I know I would not enjoy the wiring nightmare of doing this, but it is possible.

Toodles.

[circa1949]

Apologies for "bump"-ing this thread back to the top, but... here's the kind of thing I'm considering:

Don't apologize. We discuss old Allen organs! It's what we do!
Good luck with your project. Keep us updated if you decide to go this route. I would wonder if a generator board from a T12 can fill the shoes of a >= TC3 board. For example, I'm not sure but did the TC3 have a 32' pedal flue? In that case the T12 might not be able to go low enough. IIRC someone once said that the diapason and flute ranks in the TC organs share the lowest 16' notes right? So maybe it wouldn't matter if the diapason rank is where the pedal notes originate. (edit: it doesn't have a 32' stop. Did any "standard" TC organ have 32' stops?)

[MarkS]

The bottom (16') octave of the flute and diapason was shared on the TC 6. This is likely true of the TC 4 and TC 5. At some point a 32' Contra Diapason became standard on TC 4/Classic, TC 5, and TC 6.

[toodles]

The TC4 I played back in high school had a 32' Resultant, so no real 32' stop. It did rumble, however.

Toodles