Synching a Vortex?

Saul Stokes n9540283 at
Fri Jan 31 06:38:08 CET 1997

Hi Gene, I thought I would let you know that I would also be interested 
in a circuit like this if you decided to think one up.  There's probably 
quite a few people actually.


On Thu, 30 Jan 1997 gstopp at wrote:

>      I think you are on the right track...
>      It is distinctly possible that the Vortex tap footswitch input is 
>      looking for a short to ground as the trigger event, in which case you 
>      could skip the relay idea and just use the transistor to ground the 
>      input (like a Moog S-trigger). To turn on the transistor you could use 
>      a voltage trigger from a MIDI clock-to-voltage pulse converter, or 
>      like you say derive a pulse from an audio event such as a drum hit.
>      Converting the audio pulse to a voltage trigger can be done with an 
>      envelope follower plus a comparator. Actually for such a specific 
>      application you can probably throw together a simple 
>      diode/cap/resistor peak detector into an op-amp into the transistor 
>      and be done with it. Probably you'll need a 10x preamp on the front 
>      end. It might have to be tweaked to the specific drum sound that you 
>      use, but since the Vortex is expecting a "sloppy" pulse like a human 
>      foot on a switch, it probably doesn't care too much about pulse 
>      duration.
>      The way I'd figure this out is with a protoboard, an assortment of 
>      components, and a scope. Hey I have a Vortex now, maybe I'll check 
>      this out some time (next week at the soonest...).
>      A couple weeks ago I built a MIDI-clock to voltage pulse divider 
>      circuit on a single chip, but that's another story...
>      - Gene
>      gstopp at
> ______________________________ Reply Separator _________________________________
> Subject: Synching a Vortex?
> Author:  "Arnim X. Sauerbier" <arnims at> at ccrelayout
> Date:    1/30/97 6:06 PM
> Hi folks!
> Not a synth question, but a musical DIY topic nonetheless:
> I've got a Lexicon Vortex (worth the $149 sale price IMHO).  It lets the 
> user set delay times by tapping a 'delay/tap' button twice.  The box has 
> no MIDI interface, but I'd like to sync the delays to my MIDI sequences!
> I was thinking of the following hack:  use one of the outputs of my drum 
> machine as a click, then build some kind of circuit that closes the 
> contact of the 'tap' switch whenever a voltage peak (from the drum 
> machine) is detected.  
> What would such a circuit look-like?  Perhaps a transistor that triggers 
> a relay that closes the 'tap' button?
> What would you do?  Any other solutions that wouldn't involve using-up an 
> output on my Drumstation?  
> Thanks!  Sorry for my glaring ignorance. 
> ------------------------
> Arnim

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