"Chorus tuning" on single computer Allen?

[BaconByte]

So I have noticed for some time that the"Chorus tuning" tab really doesn't do anything. And for the longest time I could not figure out its purpose. I know that on 2 computer organs it puts the computers out of tune for a very nice sound but this MOS-II 305 organ is a single computer organ and I cant figure out what it does.

Due to it not fitting through my front door I have to sell it and I'd like to know every last detail on the organ.

Thanks again.

[myorgan]

Bacon,

Sorry to hear it won't fit through your door. Generally, the B-style console will fit through a door--either on end or slightly disassembled.

Celeste Tuning puts the computers out of tune with each other in a two+ computer organ. Chorus Tuning has been described in a recent thread on the Forum. You can read about it here: http://www.organforum.com/forums/sho...l=1#post427982 (and subsequent posts).

Your manual can be found here: http://www.allenorgan.com/www/suppor...nersManual.pdf. In reviewing the manual, it doesn't appear your organ had the option for Chorus Tuning. It may have been on a rocker tab, but never connected. That was a bad habit Allen had with earlier organs--they'd list all the extras on rocker tabs off to the side (i.e. Reverb, Chorus Tuning, etc.), just to remind people of what they couldn't afford to buy!X-( I'm not sure it did much good for their sales, though.

I hope you find this helpful.

Michael

[BaconByte]

My home was built when the outskirts of Detroit was all farmland and the door is just too small even taking some of it apart. If only I would have known that before I got rid of my H-100. But lessons learned.

Anyway the tab does none of what was described. If it wasn't "hooked up" where can I look or what can I do to make it work?
Forgive my ignorance. Digital instruments aren't my specialty. I knew what everything on my Rodgers was and did but this is still new to me.

[tucsondave]

The service manual 305 stop list has no "Chorus Tuning" tab listed. The tab next to Speech Articulation Off is shown as blank. The two other single computer models are prepared for tremulant generators but those tabs are marked "Chorus."
Have you compared the chorus tuning to the analog celeste voices?

td

[BaconByte]

The service manual 305 stop list has no "Chorus Tuning" tab listed. The tab next to Speech Articulation Off is shown as blank. The two other single computer models are prepared for tremulant generators but those tabs are marked "Chorus."
Have you compared the chorus tuning to the analog celeste voices?

td

It is there. It doesn't change the tone of the organ in anyway and its third from the very end.
It is right next to the antiphonal speaker tab and chiff. I have tried it with everything with every possible combination I could come up with. There are some blank tabs around but none that were mentioned.

[myorgan]

It is there. It doesn't change the tone of the organ in anyway and its third from the very end.
It is right next to the antiphonal speaker tab and chiff. I have tried it with everything with every possible combination I could come up with. There are some blank tabs around but none that were mentioned.

BaconByte,

Do you have a camera or cell phone photo that could take a picture? I think I know what we're talking about, but am not completely sure. On my 505B, all my rocker tabs to the left of the Swell are blank (see this photo: http://www.organforum.com/gallery/di..._display_media.

Michael

[BaconByte]

BaconByte,

Do you have a camera or cell phone photo that could take a picture? I think I know what we're talking about, but am not completely sure. On my 505B, all my rocker tabs to the left of the Swell are blank (see this photo: http://www.organforum.com/gallery/di..._display_media.

Michael

Here you are and here is the mystery tab in question. Plus another blank one next to the tremulant. The only other blank tab is all the way over in the pedals which I think was some sort of 32' stop. You've got a beautiful instrument. I wish mine had a custom finish like that. It'd match the music room! Though getting in the house would still be a problem.

[toodles]

There is always the possibility that the tab was changed in the field for some reason, and a slight chance that factory installed the wrong tab in this location. The only reason I can think of for the former is that the tab became broken. I did see a Rodgers Organ with a tab engraved Tierce 1-1/3' at a dealer's showroom--the dealer had it changed to the correct tab by my next visit.

[myorgan]

Here you are and here is the mystery tab in question. Plus another blank one next to the tremulant. The only other blank tab is all the way over in the pedals which I think was some sort of 32' stop. You've got a beautiful instrument. I wish mine had a custom finish like that. It'd match the music room! Though getting in the house would still be a problem.

Thank you, Bacon. To think I've been coveting a standard walnut finish all this time!;-)

Perhaps your organ was customized somewhat, and perhaps someone customized it with a Chorus Generator, be it analogue or digital, then removed it later. As Dave said, there is no mention of that tab/stop in the manual, nor have I seen it in any model under the 505B I have. On my organ, the Chorus Tuning tab does do something--especially to the Reed Chorus in the Swell. It is a minute change, but it is audible.

I hope you don't mind reading the other thread, but John gave an extensive of the differences there, and I didn't have the heart to reproduce it in my clumsy fashion.

I sure do hope you get the mystery solved. I wonder if David Casteel's 305B has the same stop?

Michael

[jbird604]

I'm voting with some of the earlier posters -- wrong tab put there by the factory or the dealer or a tech. "Chorus Tuning" was a feature of some two-computer models that shifted one of the computers slightly sharp for a very mild celeste-like effect. Not nearly as busy as "celeste tuning" but definitely more separation between the A & B computers than you'd expect with normal tuning.

But if you have a 305, it has only one computer, and that effect could not be created. There's a chance that a customer or dealer had the factory install that tab and connect it to the system in such a way that it would offset the pitch of the Great from the Swell, similar to the "Sharp Tuning" tab that is found on many single-computer MOS-1 organs. This effect might tend to make the two manuals more distinctive by giving them slightly different tuning references. But I haven't ever seen that done on a MOS-2 organ like yours, even though it would indeed be possible.

On MOS-1 single-computer organs, there is in fact a "chorus tuning" function that causes the lower octaves of the organ to go sharp and the higher octaves to go flat. This makes for some interesting "beats" that can be heard when you are playing large chords that span a couple of octaves, and for some beating between the pedal pitches and the manual pitches for example. But I don't think that particular feature was carried over to MOS-2, as it conflicted with newer enhancements to the pitch system and was completely dropped from later production MOS-1 organs.

So if you don't hear anything change, and you're sure that you are listening carefully to the pitch at both high and low ends of the keyboard, then it just isn't hooked up to anything. You can always tell a prospective buyer (who is unlikely to care anyway) that it was for an optional feature that isn't installed on this one. That would be the truth, even though none of us can tell you for sure what the intended function was to be.

[BaconByte]

Awwww..... kinda got my hopes up. Something to fix! Something more to learn about digital organs! Bummer. Welp thanks all anyway.

One more thing if I could be so bothersome. What is the difference between the two generation of MOS organs? I know MOS-II was an expansion but what exactly did they expand upon?
I do have a layman understanding how the MOS system works.

[davidecasteel]

I sure do hope you get the mystery solved. I wonder if David Casteel's 305B has the same stop?

Michael

My 305B does not have that stop. At the right end of the Stop Rail are "Random Motion Off", "Speech Artic. Off", and a blank tab. I confess I've not experimented with them.

David

[PghBear210]

The blank at the end is for if you have the Carillon feature installed in your EPROM chip rather than the Quintaden 16 on Great. You got either/or, but not both. When I exchanged the EPROM chip from a dead board, the Carillon stop suddenly became Q-16.

[jbird604]

B-Byte, the differences between MOS-1 and MOS-2 may have been previously discussed, but I can give you a few notes on that. As you say, MOS-2 is an enhancement of MOS-1, not a completely new technology, though most parts are not interchangeable.

MOS-1 was a revolutionary system, the first digital organ ever. When it was introduced it was pretty raw. As time went by, Allen figured out numerous ways to make it sound better, often making new features available as options. For example, they offered a little satellite board for the MOS board that created a slight difference in tuning between the two audio channels. They called this enhancement "frequency separation" and it was a definite improvement over the original sterile tuning of MOS organs.

Another enhancement they offered was called "dash-3" voicing (properly just -3) and you can spot MOS organs with this upgrade because they have "-3" at the end of their model number, such as "301-3" etc. The dash 3 voicing scheme placed the 8' and 4' members of each major chorus into opposite channels. An organ with both frequency separation and dash-3 voicing would then exhibit a mild "beating" effect when the 8' and 4' stops were drawn together, a very desirable thing that made the organ sound more "real" and pipelike.

There were improvements along the way in the Random Motion system, changes to the tuning schemes, other features such as "delay" and "slow pedal" options were added via satellite boards, the DAC was vastly improved, and so on. Some of the standard stops in the ROM became customizable, as certain hard-wired chips were replaced with sockets into which alternative EPROMs could be placed. A new chiff was developed. Better mixtures were available on EPROMs, as were various types of 16' and 32' pedal stops.

Around 1982, Allen decided to incorporate all these incremental changes into the standard feature set, and so they introduced MOS-2, which used a newly designed MOS board that was equipped with all these features, and more, as standard equipment rather than extra-cost options. To interface with the new MOS board, they created new Keyboard Array and Stopboard Array boards. The old clock board was integrated into the Keyboard Array, as was the Card Reader logic. Card Readers became standard on all models at that point.

The organs still produced tone in the exact same manner, and the model lineup was only slightly altered, but for the purchasers it was a win-win deal, as you got more organ for the same money. MOS-2 would've been a real hit, but before they sold a great many of these, the ADC models came out and replaced them. ADC was in many ways just a further refinement of MOS-2, but there were a LOT of improvements that made ADC models an even better value.

But many folks still consider MOS-2 a high point in Allen's product line, with organs that are highly customizable and easy to configure in many ways even today. It's a shame they only built them for a couple of years and there aren't very many of them out there, compared to the vast numbers of MOS-1 organs still in use today.

[BaconByte]

Thanks!
I knew it was explained before but the forum search didn't want to search.

Shame I can't keep it. It is a very nice instrument.

[myorgan]

I'll revive this thread because it is the only reference to Chorus Tuning I can find anywhere on the Internet (including the Allen Organ website).

I found another place where Celeste Tuning appears in every division but the Choir (& Pedals, obviously). In the Choir, it is listed as Chorus Tuning. I wonder why? Perhaps because of the theatre stops in the division? I know what Celeste Tuning does, as mentioned above, but how could Chorus Tuning different?

Michael

[michaelhoddy]

Michael, your 8000 is different than what I'm used to, with the alternate Choir voices and the vibrato controls!

[myorgan]

Michael,

Different than what I'm used to too! I'm looking forward to hearing it in person this Summer when my garage is done. There are video recordings of the Choir on a cell phone from before I obtained the organ, and they didn't sound that much different than what I'm used to. It makes me believe I might be able to voide the Choir more conservatively and have something that walks the line between theatre and classical.

Michael