Moog Music Forum

Hey all, new Moog modular user, long time synth user. I'm a little confused about the s-trig, I want to send voltage from my Korg SQ-1 sequencer to my Moog Model 10. I have the s-trig to 1/8inch cables, just curious to what settings I should set the Korg SQ-1. I also have a key step, same question there as well.

Happy Holidays,
Cheers

Well, S-Trig just means that a constant voltage is shortened to ground to raise an event. Most sequencers provide V-Trigs (Voltage) where a voltage is set to raise an event. So the SQ-1 must be configured to provide S-Trigs, or a conversion has to be done. There are adapters which do so.

I've already V-Trig to S-trig adapters: a resistor is involved somewhere in the connectors, IIRC. I'm not not sure if it is only a matter of polarity but the SQ-1 gate output can be parametrized with both polarities while in the Global Parameters Settings, cf. the user manual:

In the SQ-1 manual, Señor Korg wrote:GATE output polarity of channel A and channel BWhen the MODE button lit is lit up + (positive polarity) is selected. When the MODE button is unlit (negative polarity) - polarity is selected. With the factory settings enabled, + (positive polarity) is selected. Set this as appropriate for the device that’s connected.

Hm, the question is, what does "negative polarity" mean. If the SQ 1 provides a constant voltage, let's say +5V dc, and the event lowers it to 0V / GND, it should work wth S-Trig devices. If the constant voltage is 0V and the negative polarity event lowers it to let's say -5V dc, it won't work.

I know conversion circuits with an NPN and one or more resistors, where a positive gate pulse opens the NPN and shortens the collector to ground. The collector is connected to the S-Trig input of the Moog device. That works quite well, like in the old 950 keyboard circuit and in my clone of it.

See also 950 clone schema

The positive pulse on the trigger bar (which can be compared to a sequencer pulse event) opens Q6 which shortens the "Gate out (STrig)" connection to ground. Otherwise a constant voltage of 12V is present there via R19.

Tahbuss,
Make sure that your cables are not the problem also if you can't get the envelopes to fire.

Hey all!

Thanks for the great replies, I really appreciate you taking the time to get back to me. I ordered the two s-trig to v-trig 1/8 inch cables from Syntaur, as I've ordered parts from there before, and the service has been great. I was able to get the envelopes to trigger from both the Korg SQ-1 and Arturia Keystep, but they were inverted, my guess is due to the polarity being set to positive as default.

After reading about the polarity here from your responses, I looked in the fold out instructions that is included with the Korg, and was able to find under the Global Parameter settings, which are accessed by holding down the play button and then turning it on, I could switch the gate output to negative polarity. Viola! The envelopes are snappy like they should be! Moogy goodness! Thank you all!

One thing to note though is that by changing it as a global parameter, it changed the second cv/gate channel as well, thus now my Roland System-500 has inverted envelopes, which I can technically flip on the module, but it's a little bit of a bummer. Now, I'm looking at the new Korg SQ-64, which after flipping through the manual online, I believe has independent gate polarity settings for each channel, though I could still have misunderstood this.

I changed the keystep's settings in the midi editor as well. Thank you all again!

Now if I just had another $10,000 worth of gear to sell, I could grab that Moog Sequencer Complement B cabinet.
Problems solved?...

Glad it helped

Just wanted to say that I am looking to invest in a Model 10, and I am interested in pairing it with a KeyStep, and this thread answered my questions one hundred percent. Thank you, contributors!