"Chorus tuning" on single computer Allen?

[SchnarrHorn]

Looking at the stops, the Choir division doesn't have a clear celeste-worthy pair of stops. For 8' non-reeds, there's Diapason, Viole and Tibia at 8'. While they could be paired and celeste-ed and it would be neat to experiment, no pipe organ would pair any of them in that way (e.g. Diapason rank and a Tibia Celeste rank). I suspect Allen wanted to keep the specs pipe-organ-like as much as possible. Assuming the choir has its own pair of tuning tables, the chorus table was probably tighter than a celeste table.

When Allen went to MDS and did away with the separate celeste control, the only way to experiment is to couple the 2 alterables to another manual and pull the Voix Celeste (or whatever the celeste rank is on the specific model) to detune one of the alterables. Thus, reed celestes can be made, for example. But that takes a little more thought and work to figure out. With a separate celeste control, one can point to the two obvious ranks with which it should be used. If it's used with any other ranks, the organist is responsible for the result. In the Choir division, Allen wanted to keep it kosher so no smart aleck (think competitor) could point out the uselessness of a celeste control when there aren't any stops to pair up that way in the division.

At least, that's my take. BTW, that's a beautiful spec. Three 32' flues, a 2' and a quint in the pedal. Four 8' flues + the flute celeste II in the Great. Such luxury. 😊

George

[SchnarrHorn]

Oh, and then there's the question of why provide the Chorus stop at all in the Choir? Perhaps, it was just a matter of standardization. On a larger instrument (or one without the theater organ stops) there would have been an appropriate celeste rank and in that case, there could be a celeste tuning table and a celeste tuning stop. While Allen substituted the theater ranks for the original purchaser, they didn't want to change the controls and kept it standard. The only thing that would make sense is a chorus control.

George

[myorgan]

George,

My guess is that perhaps the 8' Viole and 4' Viole could be used as a Chorus together, but I won't know until I hear it. I'm not sure if pitches an octave apart would make a good Celeste.

Michael

[SchnarrHorn]

No, I'm thinking it's just a looser tuning on one half but not quite as loose as a celeste. I didn't realize this was an 8000. I looked at the spec sheet and yes, there would normally be a Viole and Viole Celeste stops where Celeste Tuning would make sense. The factory swapped in a few theater stops for the celeste ranks but the ability to change the tuning on half the division was still there, including the stop knob. So, they just put an alternate, looser tuning (but not celeste tuning) in the choir and controlled it via that stop knob (with a different face). Think of it as the Romantic Tuning control on the MDS models. In other words, not intended for just a pair of stops but to give the entire division a little more action in the sound due to the looser tuning.

[Admin]

Chorus is not the same as celeste. Chorus is a continuous random pitch shift. My MOS-2 Allen has a chorus tab. The chorus there was implemented by the Trem 3 units. The chorus function was discontinued in the Trem IV units.

[myorgan]

So, in a phrase, it's Allen's continuation of the Random Motion feature? Thanks, Admin. That makes more sense to me.

Michael

[Admin]

Random Motion Whind produced more of jitter in the tone than a chorus effect. I don't know of any way of describing chorus effect other than chorus, and although intact, the original tone generator system of MOS-2 is no longer connected to amplifiers, so I can't provide an example. What I can say is the "chorus" is the same chorus effect you'll find in any effects box. It's similar to a celeste, but unlike a celeste where the effect is produced by two sources with a fixed frequency variation, the chorus continually shifts the frequency of the source. It's more a very slow speed vibrato light with no amplitude variation.

It's more the equivalent of a slow speed gyro.

[myorgan]

So, would it be similar to the "Chorus" effect one would find in Audacity?

Michael

[michaelhoddy]

In ADC, each board or half a board (A side or AA side) in the case of the TG-3 and successor TG-8 boards is mapped to part of an FG board in the same cage that contains the tuning table for all the stops in the mapped groups. The Celeste Tuning tab or knob in a given division accesses an alternate pitch table on the FG board for the groups of stops which contain the celeste voices, and if you've used it, you know there's some other stops that get "celested" simply by being in the same stop group as the celeste.

I would imagine Chorus Tuning works exactly the same way in ADC- an alternate pitch table for some of the stop groups on the relevant FG board(s) that's activated by the knob, although tighter than Celeste Tuning and perhaps more randomized.

[myorgan]

Thank you, Michael. When I get the organ set up this Summer, I'll make recordings so we can remove all doubt.;-)

Michael

[Admin]

Allen describes chorus thusly in the Trem III documentation.

The Chorus is very similar to the slow speed effect from Allen Gyrophonic Projector speakers. Like the Gyro, it is cyclic in nature, but it does has the advantage of adjustable speed and adjustable Frequency Modulation (sic).

That said, I don't know if Chorus is the same as Chorus tuning. The Chorus tab is not listed on the technical info I have for the 305 MOS-2 so the organ might have been customized with the addition of a Trem III unit. The standard MOS 305 has an analog celeste generator.

[myorgan]

Great information, Admin! Thank you. Shall I assume it is in the ADC Audio documentation, or is there another source like the MOS-2 documentation for theatre organs?

Michael

[michaelhoddy]

Will be curious to find out what you discover- whether this is a variant on Celeste Tuning on the FG board, or a setting for the Vibrato on the Trem III board. My guess was based on the location of the knob- the Chorus Tuning is in the exact spot the Celeste Tuning Knob is in on a standard 8000, and the fact that this would fit in character with the rest of the stop mods from an otherwise standard 8000 that would have had Celeste Tuning anyway.

[myorgan]

On the Celeste Tuning side of things, I was able to warm the garage enough to practice for a few hours yesterday afternoon on my ADC-5400. I used my MOS Dulciana 8' and Dulciana 4' in the two alterables, and used Celeste Tuning. It extended throughout the range of the manuals. I did find that the celeste effect was not as noticeable with the pitch difference. However, when I used the Dulciana 8' in both alterables.it sounded REALLY NICE!

So the answer to the questions above is that, "Yes, the Celeste Tuning spans the full compass of the keyboard." The question I asked was whether an 8' and 4' would sound good together. The answer is that they don't celeste well. I forgot to try adding the 4' Dulciana in both alterables to add an octave celeste. Oh, well!

Michael

[jbird604]

Thank you, Michael, for reporting on that bit of research. It does seem that celestes work best ONLY when the two tones involved are very similar in tone color and are at the same basic footage. Otherwise the waves don't coincide in the manner required to produce that beautiful undulation that makes the celeste so gorgeous.

It also helps tremendously if the two tones are processed separately in the organ's electronics and even projected by separate speakers. While Allen got away with having the celeste rank sound in the same channel as the strings on their analog organs, and even on the 300 series of MOS organs, in the doubled MOS organs and in all ADC and later models the two ranks come from separate channels.

[myorgan]

P.S. I also used the Erzähler 8' in both alterables, as well as the Fernflöte 8' in both alterables. The Erzähler 8' when coupled with the Choir Erzähler sounded REALLY NICE!!! It reminded me why I've been coveting one of the Allen models which uses an 8' Erzähler Celeste in the Choir. The Fernflöte 8' also sounded quite nice as a Flute Celeste. I didn't couple it with the Great 8' Flute Dolce II, but I probably should have.

It's really nice to have options!

Michael

[SchnarrHorn]

Since Allen didn't implement 16' and 4' couplers until later, there is an ADC/MDS "String 16' & 4'" alterable card. Putting it in both alterables along with drawing the 8' Salicional & Voix Celeste stops results in a wonderful, lush string celeste sound on the Swell.

George

[myorgan]

George,

That's it-rub it in!!! A member actually made one of those cards for me, but I think my card reader is slightly mis-aligned, so it wouldn't read the card accurately-too many starts and stops. When I get the ADC-8000 set up, I plan to try it in that organ as well.

Michael

[myorgan]

Well, I scoured my MOS-1, MOS-2, and ADC manuals for Chorus Tuning, and came up with only more questions. Here are my discoveries so far:

1. In the MOS-2 manual, copies of the sticker is provided for the 2+ computer organs, which says something to the effect, the tuning is to take place with the Chorus Tuning tab engaged (I need to double-check that). Hmmm.
2. On my MOS-2 505B, the Chorus Tuning AND Celeste Tuning AND Delay ALL appear on the Swell-implying they each perform different functions.
3. In the ADC Audio manual, there is a brief reference to Chorus Tuning, but almost no details.

A thought then occurred to me: Could Chorus Tuning be something like a phase shift? I began thinking about a Reed Chorus (think "Trumpet Fanfare") where not all the Trumpets would speak at the exact same time and exact same pitch. I wonder if there is a miniscule delay between stops of the same pitch, or specific pitches within a stop, so depth would be added to the tone? MOS-2 organs have a Delay tab which does exactly that, to imitate the depth of a pipe chamber, but it is much more obvious than what I'm thinking Chorus Tuning might be. The smaller delay would not be enough to cause phase cancellation for most frequencies.

Just some musings on the topic of what Chorus Tuning actually does. I think Admin is onto something above, but I'm not sure I understand exactly yet.

Michael

[michaelhoddy]

Michael, it could be any number of things, but I think you need to consider the available options in ADC, which are basically either some different pitch table in place of the missing Celeste tuning in that division, or some additional effects that might be able to be accomplished on the Trem III if present, not whatever came before those possibilities in MOS that was not carried over into ADC.

[Admin]

I found this in Allen's technical notes for a MOS-2 505 model:

The Swell Celeste Tuning function uses the number 3 Celeste tuning deviation. It also turns on Tempered Tuning for the Swell and only while the Celeste stop is operative. The Great Chorus tuning uses the number one Celeste tuning deviation and does not turn on Tempered Tuning.

For the three computer MOS-2 805 the Chorus tab is noted as being "prepared for" which suggests to me that this implemented via optional Trem III units as I believe it is in my MOS-2 965.

[myorgan]

All useful information. Thank you so much, folks! I'll definitely be sure to make recordings once I get the organ together. I FINALLY found an electrician who will show up, so it looks like this Summer is the magic time to get the garage finished.

Thanks for your input.

Michael

[myorgan]

I FINALLY found the answer in the MOS-2 service materials I have available.😐

By now, we all know that IF a MOS-1 or MOS-2 organ up to the 305 has Celeste, it will be an analog unit mounted somewhere inside the console, like under the lid or mounted inside somewhere.

However, for the 2-computer organs, the TGU-2 board (normally only used for theatre organs) is used ONLY on the computer which has its tuning altered for the Celeste Tuning feature–generally the B computer. Now comes the answer:

The Swell Celeste Tuning function uses the number 3 Celeste tuning deviation. It also [emphasis mine] turns on Tempered Tuning for the Swell and only while the Celeste stop is operative. The Great Chorus tuning uses the number one Celeste tuning deviation and does not turn on Tempered Tuning.

Apparently, the Celeste Tuning deviation changes depending on the pin # it is connected to. When looking at the schematic, pins 1-4 of each division, the only difference I immediately see is the different level grounding they each receive. If the arrangement of the pins holds true to other Allen devices (i.e. Vibrato, Tremolo, etc.), 1 is the least Celeste Effect and 4 is the greatest Celeste Effect.

Barry, if you still need information about adjusting the analog celeste generator on your organ, let me know. I think I may have found the directions, but won't know for sure until you try them.

Michael

P.S. I am moving a MOS-1 organ from one church to another today, which has an analogue celeste in it. If they ask me to tune it, I might have enough experience to talk you through it after I'm done.

[myorgan]

P.S. I realized Admin provided the same answer just before mine. Sorry for reviving a dead thread.

Michael

[aeolian pat]

There is an Allen in a chapel, I suppose an ADC, which has two Salicional stops on the swell. It also has a Celeste tuning tab which tunes the swell to Celeste but only when coupled to the great and only when you are playing on the great with a great stop on.

[Organkeys Jones]

That sounds like how a modified MOS would work, not ADC.