From gstopp@fibermux.comWed Aug  2 18:54:02 1995
Date: Wed, 02 Aug 95 17:08:28 PST
From: gstopp@fibermux.com
To: analogue@hyperreal.com
Subject: Re: Arp Triggers and spankology

     hi all - another lengthy spouting off, this time about gates & 
     triggers....
     
     Sending controller gate & trigger rules:
     
     * The gate is a boolean OR function of all of the keys on the 
     keyboard. Any or all keys depressed, gate = high, no keys depressed, 
     gate = low.
     
     * The trigger is a narrow pulse (~10 ms) that is transmitted for 
     either of the following: 1) the gate goes from low to high, or 2) the 
     gate is already high but the CV changes because the old note goes away 
     after a new one is depressed (legato playing).
     
     Note that under these rules you will never see a trigger without a 
     gate.
     
     Receiving device envelope generator rules:
     
     The trigger starts the attack phase (and the gate is high). When the 
     attack phase is completed (envelope peak reached) the decay phase 
     starts. The envelope slopes down to the sustain level for the duration 
     of the gate. When the gate goes away the envelope slopes down from the 
     sustain level to zero at the release rate. If the gate goes away 
     before the attack phase is completed, then the envelope never reaches 
     peak and slopes to zero at the release rate. If the sustain phase is 
     in progress and another trigger comes in, the envelope slopes back up 
     to the peak at the attack rate then decays down to the sustain level.
     
     Notice that Minimoogs don't have triggers as defined above. The 
     S-trigger that Moogs have is really a gate logically and physically it 
     is a short across the two pins on the Moog's S-trig input (there are 
     some who say that "S-trigger" stands for "shorting trigger"). This 
     means that if you play legato on a Minimoog the envelope won't 
     retrigger its attack/decay phase until you lift all keys and hit 
     another one. ARP stuff has gate and trigger and you always get a new 
     re-trigger of the ADSR when you change notes, legato or staccato. Both 
     modes are musically useful. Multimoogs have both modes, selectable 
     with a switch (yay).
     
     Note that if your CV source has both gate and trigger, you don't need 
     to hook up the trigger if your destination synth doesn't support it. I 
     think on the ARP stuff that you need a trigger or else the ADSRs will 
     act funny. If you want to fire an ARP's EG's with just a gate you can 
     connect the trigger input to the gate with a 0.1uf cap.
     
     A neat trick on some ADSRs that use triggers is to set the VCF EG to 
     max mod and:
     
     A = short
     D = short
     S = zero
     R = really long
     
     so if you press and hold a key the envelope will go "bwip" but if you 
     thwak a key for an instant the envelope will rise towards the peak but 
     jump straight to the release phase and go "baaaaaoooooooowwwwww" so 
     like you can git two differnt noises outta the same patch!
     
     p.s. i still don't know what spanking is....


______________________________ Reply Separator _________________________________
Subject: Arp Triggers and spankology
Author:  lx@fht.com (LX Rudis) at ccrelayout
Date:    8/2/95 12:51 PM

     >Really ?    I have been long confused about the separate trigger and 
     >gate inputs.  And why does a Kenton have separate gate and trigger 
     >outputs ?
     
     >to drive multiple triggered envelopes on ARP gear without releasing 
     >the first note on, i'd assume...