[sdiy] How long should a Trigger pulse be?

[Adam Inglis]

The Roland TR 808, 909, 707 (and I think the 606) all put out a 20  
msec pulse from their trigger outs. These reliably trigger their  
synths arpeggiators.
On my Robin Whittle-modified 808, there is an extra trigger out of 0.6  
msec duration. This does not reliably trigger the JP8s arpeggiator.

Adam
On 19/12/2013, at 12:38 AM, Tom Wiltshire wrote:

> Hi All,
>
> I'd like the benefit of your combined experience, if I may.
>
> I'm decoding MIDI Note On/Offs and outputting Gate and Trigger  
> pulses to drive envelopes. My own envelope designs don't need a very  
> long trigger pulse in order to fire, but I thought perhaps some  
> others do.
>
> Currently I'm using 500us Triggers, but I don't have a big pile of  
> old synths here to try that on, so I don't know how well that will  
> work on vintage gear.
>
> And then of course, there's the problem of envelopes or synths that  
> don't have a Trigger input...
> I remember the Kenton Pro-2 MIDI-to-CV convertor had a "retrigger"  
> mode where it dropped the Gate briefly to allow Gate-only envelopes  
> or synths to retrigger. It didn't say how long it dropped the gate  
> for though. I'd thought to do something similar with the following  
> circuit:
>
> http://www.electricdruid.net/GateAndTriggerCircuit.png
>
> This converts Gate and Trigger into a Gate-with-gaps that will  
> retrigger a Gate-only envelope. And this is the main reason for my  
> asking the question; In this case, the output gate is essentially  
> delayed by the length of the trigger pulse, hence my desire to keep  
> it as short as possible. If it wasn't for that, I'd just use 5ms and  
> reckon that'd trigger anything.
>
> So, oh wise ones of Synth DIY, how short can my trigger pulse be?
>
> Thanks,
> Tom
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>