Roland CR-8000 Trigger Inputs

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j.dilisio
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Roland CR-8000 Trigger Inputs

Post by j.dilisio » Sat Nov 29, 2014 5:00 pm

I've been having some trouble figuring out how to add trigger inputs on a CR-8000.
It requires a -10v trigger and I want to be feeding it positive triggers so I've made a board with a bunch of inverting op amp buffers like this..
Image

This works great except that when the trigger points are connected, they no longer function when using the internal sequencer.

Does anyone know a better solution?
I was under the impression that a buffer would separate the circuits and preserve the original functionality.

The voices trigger on a falling edge of a positive pulse so you can just feed it positive triggers but I'm concerned with timing issues.

Thanks in advance for any help.
Last edited by j.dilisio on Sun Nov 30, 2014 12:49 pm, edited 1 time in total.

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j.dilisio
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Post by j.dilisio » Sat Nov 29, 2014 5:55 pm

I should also add that I've tried CD4049 or CD40106 hex inverters to invert the trigger as described for the DR-110 here..
http://electro-music.com/forum/viewtopic.php?t=53172

The problem with this method is that it doesn't allow for velocity.

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j.dilisio
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Post by j.dilisio » Sun Nov 30, 2014 12:48 pm

The voltage of the trigger points on the voice board is a steady 5v while the voltage of the op amp outputs is 0v.
I think that's why the op amp is canceling out the internal triggering.

Would it make sense to shift the op amp output up 5v?
Since there's a 5v rail on the board would I be able to do something like this with transistors?..

Image

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j.dilisio
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Post by j.dilisio » Sun Nov 30, 2014 2:55 pm

Ok,. it seems to be working now.
I'm not sure how this works exactly but I think it's offsetting the voltage by using +5v as ground and +5/-15 for power.
Here's a quickly drawn schematic..
Image
For some reason, the closed hi-hat doesn't work unless you take out that one resistor. Don't ask me why. I just found out through trial and error. :banana:

I'll post a pic when it's all together.

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robot909
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Post by robot909 » Sun Nov 30, 2014 7:01 pm

I tapped the drum sound trigger connections from the big connector on the main/power board, then made simple gate to s-trig connections and a jack for each drum sound.

here is info on doepfer's page:

http://www.doepfer.de/faq/gen_faq.htm

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j.dilisio
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Post by j.dilisio » Sun Nov 30, 2014 7:08 pm

Thanks for the info. Do you know if gate to s-trig connections are velocity sensitive?

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j.dilisio
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Post by j.dilisio » Sun Nov 30, 2014 9:38 pm

Here it is with little brother DR110 also modded for trigger inputs.
Image
Next project is an Elby 16 channel midi/trigger converter to rule them all! :flamey:

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robot909
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Post by robot909 » Sun Nov 30, 2014 9:47 pm

I don't think the S-trig is velocity sensitive, just converts a positive voltage trigger into a negative voltage trigger which the cr-8000 uses.

The cr8000 is a bad ass drum machine. Unfortunately I figured out the super easy sequencer programming just as I was selling it.

Add drum sound mods and this thing kicks ass.

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DCastillo
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Post by DCastillo » Wed Oct 04, 2017 7:51 pm

Pardon me for the drop-in post, but I would love to have some trigger inputs on my 8000, along with a slew of other mods to unlock the full potential of this machine.

Is there anyone in the states that offers this specific service? I tried contacting Gumi via blog but haven't heard anything back.

Any help is appreciated!

Cheers from Chicago!

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Post by widgetoz » Sun Oct 08, 2017 2:03 am

DCastillo wrote:Pardon me for the drop-in post, but I would love to have some trigger inputs on my 8000, along with a slew of other mods to unlock the full potential of this machine.

Is there anyone in the states that offers this specific service? I tried contacting Gumi via blog but haven't heard anything back.

Any help is appreciated!

Cheers from Chicago!
My MIDI-Retrofit-16 (MIDI2SDS-16) gives you MIDI controlled triggering along with velocity control. My MIDI-Interceptor allows both the internal controller and MIDI to trigger the drums as well as allow the internal controller to operate as a MIDI 'sequencer'

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