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Old 10-12-2009, 01:10 AM
slinkygn slinkygn is offline
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Default MPA for Rock Band drum mod

Yes, this is in the right section, I promise!

The MSA-P has been the popular go-to device for the DIY MIDI-to-Rock Band controller. I was curious if the MPA could be used to do the same thing.

Why, you ask? Well, because Rock Band controllers are velocity-sensitive. A little bit of research on what the expected output range from the pad piezos has already been done:
http://www.rockband.com/forums/showthread.php?p=173171

So my thought was, use the 5V logic outs of the MPA to feed a transistor, control base voltage with the variable resistors (set to change on velocity messages, of course), and voila, velocity-sensitive outputs ready to solder to the pad connectors.

There were a few concerns still remaining, though, that I'd appreciate some help/discussion on (besides the ever-present question of "am I just crazy and trying to come up with a circuit that'll never work?"):

1) The MPA firmware hasn't apparently received the ability to output a fixed note length like the MSA series has. Is it possible to get that implemented?

2) I haven't really thought through the switching speed of the output transistors I'd be adding. I can recall that I'd have to use a FET because switching speed on a regular BJT is pokey, but beyond that I'm not sure what to choose.

3) Any other reason this wouldn't work?
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Old 10-15-2009, 09:34 PM
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John John is offline
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Quote:
Originally Posted by slinkygn View Post

1) The MPA firmware hasn't apparently received the ability to output a fixed note length like the MSA series has. Is it possible to get that implemented?
It's possible, but it will be a while before there's an opportunity to do the coding.

Quote:
2) I haven't really thought through the switching speed of the output transistors I'd be adding. I can recall that I'd have to use a FET because switching speed on a regular BJT is pokey, but beyond that I'm not sure what to choose.
"pokey" in transistor terms is probably negligible in regards to drum timing. The latency caused by the transmission of a MIDI message (300us or so) is probably much larger than any transistor-related delay.

Quote:
3) Any other reason this wouldn't work?
I think it could work--it will probably just take some trial-and-error to get everything set up properly.
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Old 10-20-2009, 02:46 AM
slinkygn slinkygn is offline
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Just so I have some idea time-wise, when you say it might be a while, what sort of scale are we looking at? Is that days/weeks/months/years?

I just ask so I would know around when to place my order.
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Old 10-20-2009, 09:31 PM
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It would be months from now, sorry. Unfortunately there is lots of other product development work that needs to be completed first.

In the meantime, you could easily combine an MSA and an MPA (just link the MIDI In of one to the MIDI Thru of the other).

That way, you could get the fixed-length pulses from the MSA, and the potentiometer output from the MPA.
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