Which Allen MOS-1 Models Used Natural Coupling vs Synthetic?

[Max the Icie Owner]

Hi everyone,

I've read through pretty much every thread Google can find on various MOS-1 organs with coupling. I'm wondering however if we can assemble a list of which MOS-1 models used natural coupling vs synthetic coupling. Since it affects polyphony if natural. I've not had much luck finding any concrete information.


Anyone know?



Thanks,


-Max

[myorgan]

I'm wondering however if we can assemble a list of which models used natural coupling vs synthetic coupling. Since it affects polyphony if natural. I've not had much luck finding any concrete information.

Max,

Are you questioning about Allens only, or other manufacturers as well? John would be our resident expert on the topic, and from time-to-time, he's posted regarding specific models.

However, I can probably state unequivocally that ADC and MDS models used natural coupling. The MDS organs which had octave couplers may be an exception, but I'm not sure. If I'm not mistaken, MOS-2 instruments after the 505 model (and higher-doubled computers) also use natural coupling. IIRC, the MDC organs had the greatest issues with depleting resources when couplers are engaged.

Hope that helps get you started.

Michael

[Max the Icie Owner]

Thanks. I'm wondering about Allen MOS-1 models specifically. I clarified my original post. Good to know about the (large) MOS-2, the ADC, and MDS models

[m&m's]

AFAIK, no MOS-1 models normally used natural coupling. It was possible to get them to do this, by grounding a certain pin on the proper board, and occasionally people would do this, and then also have one of the keyboards to play sharp, therefore giving a Celeste effect between keyboards, but it reduce the number of notes available at one time.
Nor did the ADC models have natural coupling. The smaller ADC models did not even model the synthetic coupling properly. For instance, if the Swell tremulant was on, and the Swell was coupled to the Great, if the Great tremulant was not on, the Swell tremulant would not be heard on the Great, although you could play the same notes on the Swell and hear the tremulant.

[Max the Icie Owner]

By synthetic/natural couplers I mean synthetic is (in non-expert terms) pulling secondary versions of the stops from somewhere else instead of actually connecting the stops from one manual to the next. Duplication rather than actual coupling. Actual (natural) eats up the polyphony. Synthetic does not as it's its own generated set of stops.

[myorgan]

I get it now. I was understanding the reverse of what you describe. On my Allens, no polyphony is lost via couplers.

Michael

[Max the Icie Owner]

Michael,

They went to natural coupling at some point once they had the technology to not run out of polyphony. I think this was an issue mostly with the MOS organs, hence why I'm wondering which models had what. Yours probably does have natural coupling, once they could pull it off well. Jbird posted on various threads about the differences. I'm just looking for info on which MOS-1 models used what so I didn't include all that in the original post.

[Admin]

My Allen 965 MOS-2 has natural coupling.

[m&m's]

OK. I had never had any experience with one that large.

[beel m]

The larger MOS-1 organs have natural couplers when you "move across computers". For example, the 900-series has 2 computers for SW GT PD (doubled) and a third for CH. So if you couple the CH to GT, it is a natural coupler (and done via a 'slide switch' BTW). The 632/1200 has a computer (2 for 1200-doubling) for SW & PD and another (2 for 1200-doubling) for GT & CH, so if you couple SW to GT or CH it's natural. All MOS-1 organs except the first few S100-S200-S300 organs had natural "manual to pedal" couplers.
Hope this helps.

[Max the Icie Owner]

Beel m, I saw somewhere that you regularly play a MOS-301-B. What does that have specifically?

[beel m]

Max, my church's 301 is the "deluxe" 1 computer MOS-1 with an extra 37-note analog celeste generator. Ours was built in mid-1976 and sounds very good in our small building; has double audio (16 and 32A&B cabinets, not HC) up in the rafters plus I added a subwoofer on the floor in a corner. I'm glad we have the open-back "old" cabinets because of the location of the speakers; if they were closed-back HC's, I wouldn't be able to hear the organ properly.
Because it has only one computer, it has only a synthetic S-G coupler, but I added a natural S-G coupler (which chews up polyphony, but I use it for special effects) as well as Pedal to Swell and Great to Swell couplers (both natural) also for special effects.
Is that what you wanted to know?
I also personally own one of the first S100 organs, also one computer, which I modified the same as mentioned above.
Regards, Bill

[Max the Icie Owner]

So it's synthetic as standard. Thanks. The one I've been looking at is the "C" cabinet, with the celeste. Someone had mentioned that the polyphony would drop to six when the SW to GT coupler was used. Thank you.

[Admin]

The polyphony doesn't actually decrease with these early models using natural coupling. It's just distributed as needed among the coupled divisions.

[jbird604]

Loss of polyphony due to coupling is virtually a non-issue with Allen MOS organs. In the few cases where the "natural" coupling is invoked, there is a good reason for it. It is used in certain models to produce a genuine celeste without resorting to a second computer. This type of celeste naturally cuts the polyphony to six keys, but it is only when the celeste is in use.

The other use of the natural coupler, as the manual to pedal coupling in certain versions of certain models, was done to allow percussion and tremolo to couple to the pedals, or to preserve the correct channeling of certain stops. Having a natural manual to pedal coupler only reduces the polyphony by the number of pedal keys held down at once, which under nearly all conditions is going to be just one or two. (Yes I know that there are certain very unusual organ pieces in which a "chord" is played with the pedals, and that could perhaps be a problem with some organ models!)

So unless you misuse the organ or expect it to do something it wasn't designed to do, you will NEVER even be aware of the key-down limit. Now, all bets are off if you are playing one of the wretched MDC models and trying to play the celeste effect on the swell while using the carillon on the great. You won't be able to play more that one or two notes if you try that!

But absolutely no worries about any polyphony issues under any normal circumstances with any model Allen worth its salt.

[Max the Icie Owner]

Good information. Thank you all.