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  #1  
Old 06-26-2012, 06:24 PM
toolguy toolguy is offline
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Default Midi amp control.

Hello.
Looking to build a rack unit that is servo driven (rc) to change presets on a guitar preamp. The servos will basically be mounted in a 1u enclosure,with the servo ends sticking through the faceplate connected to "pulley" servo horns. The unit would be mounted above the preamp and a similar set of pulleys would replace the potentiometer knobs and be connect together via belts or o-rings. This would in turn allow an older non midi preamp to become midi tunable via cc messages (ie. gain/treble/bass could all be servo rotated).

I know I need a midi to servo controller for this but am in the dark on how to get it programmed once the hardware portion of the unit is built.

I have both machinist and automotive repair background (over 20 years). I also have raced rc cars for 30 years (so I am very familiar with servos). To boot I have slight experience with some hexadecimal editing
from working on a bit of ecu re-mapping code (although this was through an interface that would point you to the correct addresses in the code).
I also have a fair idea on how midi mapping works (just from playing guitar for a long time and having midi rack gear).
I see there are a few controllers out there that will do the job...but this forum attracted me to the md24.

I guess my question(s) would be.
Am I biting off more than I can chew? Can a novice get this to operate correctly with next to zero programming knowledge?
Or...Once I get this built. Are there any "programmers for hire" that would be willing to get the knobs stepping correctly for me....for a fair price lol?

Thanks for any help/advice.
Don't worry about squishing any dreams.

Last edited by toolguy; 06-26-2012 at 06:44 PM.
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  #2  
Old 06-27-2012, 11:48 AM
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John John is offline
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Quote:
Originally Posted by toolguy View Post
Hello.
Looking to build a rack unit that is servo driven (rc) to change presets on a guitar preamp. The servos will basically be mounted in a 1u enclosure,with the servo ends sticking through the faceplate connected to "pulley" servo horns. The unit would be mounted above the preamp and a similar set of pulleys would replace the potentiometer knobs and be connect together via belts or o-rings. This would in turn allow an older non midi preamp to become midi tunable via cc messages (ie. gain/treble/bass could all be servo rotated).

I know I need a midi to servo controller for this but am in the dark on how to get it programmed once the hardware portion of the unit is built.

I have both machinist and automotive repair background (over 20 years). I also have raced rc cars for 30 years (so I am very familiar with servos). To boot I have slight experience with some hexadecimal editing
from working on a bit of ecu re-mapping code (although this was through an interface that would point you to the correct addresses in the code).
I also have a fair idea on how midi mapping works (just from playing guitar for a long time and having midi rack gear).
I see there are a few controllers out there that will do the job...but this forum attracted me to the md24.

I guess my question(s) would be.
Am I biting off more than I can chew? Can a novice get this to operate correctly with next to zero programming knowledge?
Or...Once I get this built. Are there any "programmers for hire" that would be willing to get the knobs stepping correctly for me....for a fair price lol?

Thanks for any help/advice.
Don't worry about squishing any dreams.
Hi Toolguy, welcome.

If you can take care of the mechanical part, I think we can definitely get the MD24 configured to make things work the way you would like.

Getting the MD24 to drive the servos in response to the CC message of your choice will not be particularly challenging. I'd be glad to help out with the MD24 configuration sysex and any questions you might have.

This sounds like a great project, so I look forward to hearing more about it.

My advice would be to get an MD24 and a servo that you'd like to use first. Then you can see how the MIDI response works before you take the time to do all the pulleys and belts.

I think you'll be surprised how quickly the MIDI stuff will be taken care of.
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Old 06-27-2012, 01:13 PM
toolguy toolguy is offline
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Awesome.
Guess my only question (for now) before I get going would be...
Can I just use one 6v power supply for the unit and the servo power rail?
Or is a separate unit (or voltage step down from a 9v supply for the servos) preferred?
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Old 06-27-2012, 01:20 PM
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John John is offline
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Originally Posted by toolguy View Post
Awesome.
Guess my only question (for now) before I get going would be...
Can I just use one 6v power supply for the unit and the servo power rail?
Or is a separate unit (or voltage step down from a 9v supply for the servos) preferred?
Depending on the quality of the power supply, sharing it between the servo and MD24 can be a bad idea. The reason being that servos can draw lots of current at times. A cheaper power supply (like a wall wart) can exhibit a voltage drop in that circumstance, which can lead to unpredictable behavior from the MD24.

That said, if you have a solid regulated supply that can handle the servo power requirements, it may be ok.
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