From gstopp@fibermux.com Fri Jun 21 15:02:20 1996 21 Jun 96 18:02:04 +0500 20 Jun 96 19:40:47 +0500 1: 40 -0700 From: gstopp@fibermux.com Date: Thu, 20 Jun 96 16:31:57 PDT Encoding: 87 Text Subject: Re: Trigger=Gate? Well here's the way I've learned it over the years..... This can get into a terminology issue because some manufacturers (and therefore synthesizer players) use the word "trigger" to describe a signal that lasts for the duration of a key depression, and other manufacturers use the word to describe a narrow voltage pulse that signifies the start of some event. The largest consensus is that a "gate" is a logic state that, when active, indicates that a key is being depressed on the keyboard, which goes inactive when all keys on the keyboard are released. A "trigger" is a narrow pulse that indicates that a key was pressed on the keyboard (even if some other key is still being depressed) and does nothing when keys are released. ARPs use the terms exactly as described above. Moogs use the word "S-trigger". This stands for "shorting trigger" and should really be called "shorting gate" using the above definitions. Other synthesizers use the word "trigger" to mean "gate" too, but exactly which ones I forget at the moment. Here's the trick - if a synthesizer only has a trigger, it is probably really a gate, if we assume the definitions above. The gate is used for AR envelopes and the sustain portion of ADSR envelopes. The trigger is used to start the AD portion of ADSR envelopes. Sometimes an ADSR only needs a gate, like on a Moog. Inside however somewhere in the envelope generator a trigger is actually being produced, derived from the rising edge of the gate, but there is just no jack to patch in an external one. The trigger was invented to overcome the non-retriggering envelope behaviour of the type you will find on the Moog modular or the Minimoog. Generally, ARPs had triggers and gates and retriggered their ADSRs on new keys even if the old keys were still depressed. So on a Minimoog if you played a real fast mono lick with one hand with a quick AD envelope, the thing would only retrigger every few notes (depending on how sloppy you played). But on an ARP, every single damn note would retrigger the AD portion of the ADSR no matter how sloppy your playing was - great for fooling people into thinking you really had fast fingers. Note that in an act of sheer defiance to the product line, the Multimoog has a switch for single/multiple triggering (being the incredibly clever and enjoyable machine that it is). Some trigger-producing keyboards only output a trigger when the gate goes active or the note changes, rather than when any key is depressed. For example, on a low-note priority keyboard, play a low note (gate and trigger), hold that note, play a high note (gate still but no trigger), keep holding the high note, let go of the low note (gate still plus trigger), release high note (no gate). Some monophonic philosphers (like Dave Rossum of Emu fame) believed this to be the true way to do it. As for voltages - it varies. As far as I know triggers are always short (~10 milliseconds or less) positive voltage pulses of at least 5 but not more than 15 volts. Between triggers the voltage is zero. ARP gates are positive voltages when a key is down, zero volts when all keys are up. Moog S-trigs short the two wires together when a key is down, and don't short them together when all keys are up. This is why you can trigger (or gate, to be exact) a Minimoog by sticking a bent-up paper clip into the S-trig input jack. I hear that old Korgs have a reverse gate (zero volts is gate, positive voltage is no gate). Is this right? I have no Korg analogs. - Gene gstopp@fibermux.com Subject: Trigger=Gate? Author: Patrick Nolan at ccrelayout Date: 6/20/96 12:33 PM Is anyone here familiar with trigger? I have heard that trigger is the same thing as Gate, is this true? Patrick