Triggering a Model 15 from a Mother-32

System 55 • System 35 • Model 15
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Skotchi
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Joined: Mon Aug 21, 2017 10:21 pm
Location: Austin, Texas

Triggering a Model 15 from a Mother-32

Post by Skotchi » Fri Apr 10, 2020 4:07 pm

Hello,
I’m hoping someone can explain this to me like I’m 5 years old: I have a Mother-32 and a Model 15, and I would like to use the Mother-32 sequencer to trigger the Model 15. So a couple questions:

1. Do I simply connect the Mother-32 Trigger Out to the Model 15 Trigger In, along with the CV Out to the Controller In? Note: I do have the appropriate adapters to go into the Cinch Jones input.
2. Are the voltages compatible? Or do I risk damaging the Model 15 without stepping down the voltage?
3. Any additional details I need to be aware of?

Many thanks!

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dingebre
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Re: Triggering a Model 15 from a Mother-32

Post by dingebre » Tue Apr 28, 2020 4:29 pm

Skotchi wrote: Fri Apr 10, 2020 4:07 pm Hello,
I’m hoping someone can explain this to me like I’m 5 years old: I have a Mother-32 and a Model 15, and I would like to use the Mother-32 sequencer to trigger the Model 15. So a couple questions:

1. Do I simply connect the Mother-32 Trigger Out to the Model 15 Trigger In, along with the CV Out to the Controller In? Note: I do have the appropriate adapters to go into the Cinch Jones input.
2. Are the voltages compatible? Or do I risk damaging the Model 15 without stepping down the voltage?
3. Any additional details I need to be aware of?

Many thanks!
First, some information on triggers/gates. A trigger is a fixed width, very short duration pulse meant to initiate an action but not be continuous. A gate is a variable duration pulse meant to initiate an action, but also prolong some aspect of the action. For example, a trigger may be generated on a key down event and tell a sample and hold to sample a voltage and hold it. A gate may be generated from a key down event, too, but will stay active for as long as you hold down the key. A gate is typically used to control an envelope generator and will cause the EG to ramp up, then decay to a sustain point, held as long as the key is down, then decay when the key is released (Note the ARP 2600 has to have both a trigger and a gate to drive the EGs).

There are two traditional types of triggers/gates. First is the "S-Trigger/Gate", the second is a voltage trigger/gate. The Model 15 uses S-Triggers/Gates as opposed to voltage triggers/gates like the Mother-32. The "S" stands for "Switch" or as explained on page 188 of the Moog Modular Operations Manual, "Short-to-Ground". For historical perspective, even Moog mixed and matched S-Triggers/Gates and voltage triggers/gates. Moog's 960 sequencer needed voltage triggers/gates to run it and generated voltage triggers/gates along with control voltages. It required an additional module, the 961, which converted S-Triggers/Gates to voltage triggers/gates as well as a section to combine the voltage triggers/gates generated by the sequencer and convert these combined triggers/gates to a single S-Trigger/Gate output. There's more to the 960/961 combination than this, but I think this description is sufficient for here.

S-Triggers/Gates:
The S-Trigger/Gate is typically an open collector transistor with a grounded emitter so that when the transistor "switch" is on, the collector is at ground potential. When the transistor "switch" is off, the collector is floating. Some circuits have a pull up resistor on the collector so that when the transistor "switch" is off, the collector is at the positive voltage supply potential. Since the collector is the output, this means when the S-Trigger/Gate is active, it is shorted to ground. This design has the advantage that if you want, you can combine triggers/gates from multiple sources simply by plugging them into a multiple with no fear of damage or bizarre behavior. This "ANDs" the triggers/gates. In contrast, to combine voltage triggers/gates, you need a mixer which can mix DC voltages, that is, DC coupled. See the Moog 961 module discussion above.

Voltage Triggers/Gates:
These are simply a positive going pulse when active and ground when inactive. Effectively, they are the opposite of an S-Trigger/Gate.

To your problem, you must convert the trigger/gate from the Mother-32 to an S-Trigger/Gate first. This isn't difficult, but must be done. Roger at Synthesizers.com sells a pre-made cable to do this:

https://synthesizers.com/qmvs.html

The only difficulty is you will need an adapter to convert the 1/4 inch jack to a 3.5mm jack to plug into your Mother-32.

If you want to do it yourself, on this page:

https://synthesizers.com/gates.html

Roger has an excellent discussion on gates and triggers and near the bottom, he has a link to the schematic. Look for the words "Here's the circuit".

The Cinch-Jones connectors are still available, but expensive. You can find them on ebay, or I buy them from Tedss.com;

https://www.tedss.com/catalog/details/2025004554 - Female
https://www.tedss.com/catalog/details/2025004574 - Male

I hope this helps. PM me if you want to discuss further or have other quesitons.

David
David

http://analoguerealities.com
http://analoguerealities.blogspot.com

Skotchi
Posts: 25
Joined: Mon Aug 21, 2017 10:21 pm
Location: Austin, Texas

Re: Triggering a Model 15 from a Mother-32

Post by Skotchi » Tue Jun 09, 2020 3:01 pm

Hi David,

Thank you so much for the detailed reply-- this is super helpful. I'll take some time to fully absorb the info, and if I have any additional questions, I'll PM you.

Thanks again,
Stefan

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dingebre
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Re: Triggering a Model 15 from a Mother-32

Post by dingebre » Wed Jun 10, 2020 11:01 pm

My pleasure. Happy Knobbing!! :)
David

http://analoguerealities.com
http://analoguerealities.blogspot.com

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