[sdiy] Roland CR-8000 triggering

Ullrich Peter Peter.Ullrich at kapsch.net
Sun May 24 18:15:16 CEST 2015

I installed the MIDI2SDS inside my TAMA TS-305 and I can still use the etxernal triggers and the midi triggers.
I added a resistor in series to the MIDI2SDS output and put the signal directly to the TS-305 inputs.

As the resistor value was quite high I had no problem in changing the original trigger behavior.

Try some values in the range from 1k / 10k / 100k.
Maybe it will also solve your problem.
But maybe the input to the CR-8000 sound stages are not that sensitive...
This way you could add a summing stage in front of the sound stages so that both triggers come through as intended without disturbing/changing the other...



Von: synth-diy-bounces at dropmix.xs4all.nl [synth-diy-bounces at dropmix.xs4all.nl]" im Auftrag von "Adam Inglis [21pointy at tpg.com.au]
Gesendet: Sonntag, 24. Mai 2015 01:24
Betreff: Re: [sdiy] Roland CR-8000 triggering

Many thanks for all the replies , and Nick, thanks for the schematic.

I guess, as Laurie points out, what I want would mean having digital
and analogue signals on the same bus!
A feature of the MIDI2SDS that I am hoping to exploit is that the
trigger pulse amplitude is proportional to midi note velocity. I need
to do more tests but I think the CR voices may respond quite nicely to
Unfortunately many of the suggestions would defeat this response.

Looks like it's going to be a case of either/or ... so some kind of
switching between the two control options will be needed.


On 24/05/2015, at 3:26 AM, Richie Burnett wrote:

> I guess the *logical* way to do it would be to use an AND gate on
> each instrument trigger line between the cpu board and the voicing
> board, to combine the logic outputs from the CR-8000's own cpu and
> those from your trigger board.
> An AND gate will give a low output level if either of its inputs
> goes low.  Therefore you should be able to trigger each voice either
> by the CR-8k's own CPU or via your new trigger board. It does
> require an AND gate for each instrument though, but you get four in
> a chip.
> There may well be some cheaper way of doing it, but that's the
> method I would investigate. Hope this helps :-)
> -Richie,
> Sent from my Xperia SP on O2
> ---- Adam Inglis wrote ----
>> I'm looking at installing a midi to trigger interface in my CR-8000,
>> but I  want to retain the internal trigger function. I need a way of
>> isolating the two trigger sources from each other.
>> The internal trigger system is from the CPU, via some pull-up
>> resistors and a buffer, giving negative-going triggers from 5 - 0
>> volts, seen in this pic here
>> http://www.adambaby.com/images/tech%20pics/CR8000/CR8k_CPUtrig.png
>> These triggers go to the various analogue voice circuits, here's a
>> couple of examples, bass drum and hand clap
>> http://www.adambaby.com/images/tech%20pics/CR8000/CR8k_BDtrig.png
>> http://www.adambaby.com/images/tech%20pics/CR8000/CR8k_claptrig.png
>> I tried duplicating the input capacitor seen at the trigger entry in
>> these voice circuits, for each trigger source, however this
>> attenuated
>> the  pulse too much resulting in a different voicing (proving that
>> these circuits can be "velocity" or voltage sensitive).
>> Elby Designs, who make the MIDI2SDS16 interface that I'm testing, say
>> that in general you can't have both connected at once.
>> Any thoughts?
>> cheers
>> Adam
>> (BTW, Roman asked re a previous post whether there was any change of
>> voicing with pulse width variation. In the first pic you can see they
>> quote a huge range of variation as the width varies with the tempo,
>> from 4 - 70 milliseconds. So I guess the pulse width can't be
>> critical. I haven't tested below 4 ms though.)
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