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

[Julian]

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.

I'm in the process of working out something along the same lines, but with
an octal led driver ic in the middle of it all, in order to buffer the
trigger out, and give me a nice clean output.  I will loose the change in
voltage, associated with the accent, but this is fine / good for me.

The trigger ins I can give you working information on when I get up (its
Sunday - im in bed typing on the laptop ; ).

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.

Cheers, Julian

----- Original Message -----
From: "Anthony Bisset" <abisset at dspaudio.com>
To: <synthdiy at sdiy.org>
Sent: Sunday, September 25, 2005 9:00 AM
Subject: [sdiy] TR 606 trigger i/o modification help and notes


>
> 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