[sdiy] TR 606 trigger i/o modification help and notes

[Anthony Bisset]

> I don't know if analogue solutions do the trigger outputs in the same way,
> but ive heard that their mod makes the machine unstable, if all trigger outs
> are used at the same time.

The rumors are true, the analogue solutions trigger out mod is raw.  No
decoupling or buffering.   I purchased it out of curiosity.  Never paid so
much for ribbon and 1/8inch jacks.  Almost unethical really.

I guess it depends on how you define instability...  I'm not noticing any
problems when I use 5 of the instrument trigger outs along with 5 of the
trigger in's.  I do get a bit of LED dimming since I'm eating lots of
current, but the processer isn't glitching.  Maybe some people get
dropped notes.  Your octal led driver IC solution seems a good ticket.


> Those 6 oscillators - if you wanted to go crazy, then, if I remember right,
> the other resistor there controls their level. What about a pot in there,
> for each one, so you can controll their level too? The only problem there is
> you'd have to use shielded cable, I suspect, and the 606 is cramped enough
> as it is.

I will document this as well.  While going crazy, I'd like to sort out a
instrument rush feature (I added pushbuttons below each instrument).
The user could push the button and get a retrigger of the instrument at
some multiple of the internal clock.  Add a CV in for each of these and
you've got a very flexible percussion system with a bit of modular kit.

-Anthony


> > I could use a bit of help confirming I have chosen the appropriate points
> > to extract/mix trigger pulses. I am experiencing some cross triggering.
> > Whenever I externally trigger the hi-hats low or hi-tom are also
> > triggering.
> >
> > In order to add trigger in/out functionality to the 606 I added:
> >
> >      OUTPUTS (center pin)   INPUTS  (TRIG -> DIODE -> DIODE BELOW)
> >
> > BD   Q15     DIODE from R63 -> Q15 (center pin)
> > SN   Q18     DIODE from R98 -> Q18 (center pin)
> > HT   Q302     DIODE from R311 -> Q302 (center pin)
> > LT   Q304     DIODE from R313 -> Q304 (center pin)
> > CY   Q29             DIODE from R141 -> Q29 (center pin)
> > OH   Q27     DIODE from R138 -> Q27 (center pin)
> > CH   Q22     DIODE from R133 -> Q22 (center pin)
> >
> > Robin Whittle  suggested I boost the 15v trigger signal by .6 volts (since
> > we lose that much with our trigger mixing diodes)...  Is this simply a
> > matter of changing some resisters around the 15v supply IC or do I need
> > to operate locally at each trigger point?
> >
> > As promised I'll forward a well documented list of 606 mods (some new,
> > some improved) to sdiy, confusedmachines, AH, etc when I'm done.
> >
> > The discussion on vactrols led me to utilize one on the snare section to
> > prevent crackles when changing the decay (something about the transition
> > lag prevents the circuit from crackling).
> >
> > Also, P9's old stuff about the schmitt trigger IC led me to install pots
> > in place of the resisters that tune the 6 oscillators.  The result is very
> > cool PWM/ringmodish clangs and bells with the cymbal and hats.
> >
> > Next I'm working on a New 606 BassDrum composed of BBD as feedback
> > oscillator with clock rate being swept down to drop pitch. Grimey.
> > I used to make kick drums with a ue405 in feedback loop config with ms20
> > filter regulating frequency.  909/808/xbase kicks sound boring now.
> >
> > I can basically  replicate it on my WAD with VCFS but the WAD doesn't
> > have enough clock bleed through (yeah, not enough!!!).  The UE 405
> > compression circuit was probably helping too.
> >
> > -Anthony
>
>