Programmers in Emersons Moog Modular???

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TonvaterJan
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Programmers in Emersons Moog Modular???

Post by TonvaterJan » Thu Aug 15, 2019 11:45 am

Maybe this got covered here already, but how exactly are the program-modules in Emos Modular working?

From the pictures and some shady infos on the web, I get the impression
that the programmers contain many little sliders and a vast amount of multi-pin-connectors which route to an internal matrix of pre-routed CV and Audio paths, and replace the position of the Other Modules‘s knobs and sliders (VCOs, VCFs etc.).
This would be a little bit like the UserProgramMemory of the CS80...

Is this correct? Does it work like that?

Seems awfully complicated and excessive when done like that - and it would be necessary to modify every controlled module in the system.

Please share your knowledge...
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cornutt
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Post by cornutt » Thu Aug 15, 2019 12:03 pm

Yeah, pretty similar idea to the CS80. The Moog modules used a backplane for power, and I think it had some extra pins that were intended for signal routing and could be customized; the programmers probably used those. Here's a Sound on Sound article that has a photo of the guts of one of the programmer modules:

https://www.soundonsound.com/people/reb ... og-modular
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Post by ualslosar » Thu Aug 15, 2019 1:56 pm

There is an interesting discussion regarding patching a live ELP performance at
http://machines.hyperreal.org/manufactu ... merson.txt

Also road crew stuff: http://ladiesofthelake.com/cabinet/Roadie1.html

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BKehew
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Post by BKehew » Tue Aug 27, 2019 3:49 am

The Emerson 1CA system uses cards with small sliders and pots (as you mentioned) which are in SERIES with the panel parts. The setting of the filter cutoff is adjusted by both the front panel AND the preset inside. There are also switches to adjust the octave of each oscillator up/down across 3 octaves.

(The preset cards were once in their own box, set on top in the first 2 years or so, then built into the system later.)

There was a multipin jack for external preset selection using a remote box (Keith used to use a wooden bar just above the Hammond keys, with small buttons) he could easily change patches without reaching far.

In later decades, the remote box was not used, so he always used the front panel lighted buttons. We built a new box (now on display in the MET Museum in New York City) which allows easy remote switching as he had done in the '70s. Just for fun, we added a small sequencer/clock to run through all the presets in a cycle, so Keith would hold down one key and have it jump through all the preset sounds at any speed he wanted. The presets are a hard-switched connection, so there is no gap or loading when selecting a new preset, it's instantaneous.

So many people do not realize his instrument had presets for live shows since 1969. That's far ahead of the game for commercial units. It seems the later offshoot was the simple presets available on the Moog Satellite in 1972.

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Post by cornutt » Tue Aug 27, 2019 9:36 pm

What mechanism was used to actually change from one patch to another? Was there a big box o'relays somewhere inside the case?
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Post by noddyspuncture » Wed Aug 28, 2019 5:44 am

cornutt wrote:What mechanism was used to actually change from one patch to another? Was there a big box o'relays somewhere inside the case?
I have a copy of the service manual...

Yes, each module responding to the preset box needs "customising"... somewhat heavily..!

It's all done with light bulbs & LDR's. I always knew that was the system but always wondered how can they get an LDR to be reliably at the same resistance each time..? But it doesn't work that way. The bulb lights fully.

However there is an anomaly.. for example, you have to set say the EG potentiometers fully clockwise for the presets to work. This is because they are all high value pots (1meg I think)... and when the bulb lights, the LDR basically 'shorts' and puts one of the sliders across the high value pot. This means that then you can turn the EG pot down to a LOWER resistance, in effect over-riding the preset slider... but obviously, a higher one will have no effect.

In this way the system is limited. Same goes for the filter frequency. You need to set it to closed (anticlock) and then the preset can open it on the slider, again with a bulb lighting and an LDR basically introducing the slider across the pot.

Footages can also be switched, and mixer levels altered... again using the bulbs... it's a very simple system really.

So basically to use the preset box you do need to set controls in certain ways and then work from there. I suppose, also if you change a preset during performance you need to remember to turn a control back fully up, or fully down, otherwise the next selected preset won't be accurate..?

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Post by cornutt » Wed Aug 28, 2019 1:26 pm

noddyspuncture wrote: It's all done with light bulbs & LDR's. I always knew that was the system but always wondered how can they get an LDR to be reliably at the same resistance each time..? But it doesn't work that way. The bulb lights fully.
Holy crap. So basically each light bulb / LDR pair is a solid-state resistor. When the light bulb is on, the LDR puts the control in the programmer module in parallel with the pot in the module being controlled. Sure seems complicated... LDRs of that era did not go to an especially low resistance when on, as far as I know, so there would have had to be some compensation in the programmer to make the programmer's setting scale properly. Wow.

So basically to use the preset box you do need to set controls in certain ways and then work from there. I suppose, also if you change a preset during performance you need to remember to turn a control back fully up, or fully down, otherwise the next selected preset won't be accurate..?
I suppose so. My understanding is that, in the later years, Emerson relied almost entirely on the programmers during live performance and seldom touched any of the module controls. It wasn't like the "Pictures At An Exhibition" era where he did a lot of on-the-fly tweaking. (I'm surmising based on what I've read; the only time I got to see Emerson myself was on the Emerson, Lake & Powell tour, and he did not bring the Moog with him on that one.) I suppose there was a "cancel" mode in the programmers to turn everything off, so that the module controls could be used if desired.

Just wow. Those light bulbs would have created a lot of heat, it seems to me. Wonder how they kept those 901A VCOs in tune with all that heat around. I also wonder how often they had to change light bulbs, and how big a power supply it took to power them all. Not to mention all of the module modifications needed to work with the system.
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Post by noddyspuncture » Wed Aug 28, 2019 3:52 pm

It probably didn't need a bulb per LDR as I think the presets were universal in that once selected, everything needed to be set - it wasn't selective as to which individual control was preset. Although having said that - I see that the front panels have a lockable trimmer now and switches for the three oscillators. I assume the oscillators could be individually isolated from the preset front panel...? Anyway, that wasn't how it was originally... I think that was a Nick Rose modification. Nick worked for Emo on the Works tour and rebuilt the presets into the format we see today - 1U panels with buttons and trimmers/switches for two presets . He also did a lot of work on the GX-1.

Anyway I digress... you could put a few LDR's around one bulb, so to speak. And yes, basically the bulb/LDR acted like a switch putting the trimmer associated with it into circuit.

There will have definitely been a 'panel' setting, over-riding the presets. When you look at some early photos of the rear of the Modular and see the cables coming out of the preset box to the Modular you can see that there was a lot of wiring - very thick cabling and quite a few of them. Each module controlled by it needed modifying. Obviously there were some that didn't like VCA's etc... also all the patching needed to be in place... the preset box could only work with the patching which was used, it couldn't re-patch so to speak.

I don't know exactly how low LDR's of the era went but it obviously worked - or maybe just worked "after a fashion"...? It will definitely have had it's limitations. But remember, I am talking about how it was when it was installed and used in the 70's. Maybe more recently it has been modified to work with a more modern approach... who knows, I only have the original service notes.

cornutt wrote:
noddyspuncture wrote: It's all done with light bulbs & LDR's. I always knew that was the system but always wondered how can they get an LDR to be reliably at the same resistance each time..? But it doesn't work that way. The bulb lights fully.
Holy crap. So basically each light bulb / LDR pair is a solid-state resistor. When the light bulb is on, the LDR puts the control in the programmer module in parallel with the pot in the module being controlled. Sure seems complicated... LDRs of that era did not go to an especially low resistance when on, as far as I know, so there would have had to be some compensation in the programmer to make the programmer's setting scale properly. Wow.

So basically to use the preset box you do need to set controls in certain ways and then work from there. I suppose, also if you change a preset during performance you need to remember to turn a control back fully up, or fully down, otherwise the next selected preset won't be accurate..?
I suppose so. My understanding is that, in the later years, Emerson relied almost entirely on the programmers during live performance and seldom touched any of the module controls. It wasn't like the "Pictures At An Exhibition" era where he did a lot of on-the-fly tweaking. (I'm surmising based on what I've read; the only time I got to see Emerson myself was on the Emerson, Lake & Powell tour, and he did not bring the Moog with him on that one.) I suppose there was a "cancel" mode in the programmers to turn everything off, so that the module controls could be used if desired.

Just wow. Those light bulbs would have created a lot of heat, it seems to me. Wonder how they kept those 901A VCOs in tune with all that heat around. I also wonder how often they had to change light bulbs, and how big a power supply it took to power them all. Not to mention all of the module modifications needed to work with the system.

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