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 Forum index » DIY Hardware and Software » Thomas Henry designs
MPS with Roland pad/trigger
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dimebucker



Joined: May 02, 2014
Posts: 11
Location: dublin

PostPosted: Thu Jan 29, 2015 3:27 am    Post subject: MPS with Roland pad/trigger Reply with quote  Mark this post and the followings unread

Hi guys,
Is there any reason the MPS would not work with one of the Roland 'PD' series, for instance:

https://www.youtube.com/watch?v=iYkA-xSrPfg

Another thing I was thinking about is trigger velocity? Is that possible, or even desirable?
I presume you would need some sort of volume attenuating circuit, if thats too complex it would be nice if you could route velocity to filter cutoff Smile

any thoughts/ideas welcome!
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richardc64



Joined: Jun 01, 2006
Posts: 679
Location: NYC
Audio files: 26

PostPosted: Fri Jan 30, 2015 2:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Can't help with your pad problem, but the MPS (and Bass++ and UD-1) won't respond to velocity because the trigger input opamp is configured as a comparator: Its output is off/on. You'd need to rewire it as an amplifier. Copy the DS-7 structure or try the one I've been using. Although both are single-supply, thanks to the diode(s) on the output they'd work with a TLO74 or other opamp powered dual-supply. You might have to tinker with the R & C values.


basic_intf.jpg
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To get the MPS "Locked" feature, switch the opamp (+) input to a positive voltage.
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dimebucker



Joined: May 02, 2014
Posts: 11
Location: dublin

PostPosted: Mon Feb 02, 2015 7:19 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the reply, v. interesting.

So this modification would mean a separate input for the piezo/pad?

Ive attempted to implement your design onto the MPS schematic below (pink colour), I'm quite a novice in this regard but trying to learn as I go. Would this work or will the Lock/Triggered switch need to be different?



.


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richardc64



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Audio files: 26

PostPosted: Mon Feb 02, 2015 8:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Hmmm...in my circuit the Sensitivity control is only for the piezo. The opamp has enough gain that even a 1V external trigger amplitude produces a full +V at the opamp output.

I think a resistor of some value is needed on the -15V "Locked" terminal of S1. You can just leave the other terminal unconnected.

Nice color choice, btw.


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