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  #1  
Old 06-23-2012, 09:01 PM
Cynosure Cynosure is offline
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Default Play the note frequency?

Is it possible to use this or one of the other controllers to play the frequency of the most recently pressed midi note with logic level pulses?

For example, pressing A4 will output on and off pulses at 440Hz.

I need something to do both this and send an ON logic pulse every time a note is pressed (which i see that some of the controllers here already do).

If there can't work like that, then could you recommend an easy method for controlling the frequency of a simple oscillator? It is for music, so it needs to be precise.

Thanks!
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  #2  
Old 06-24-2012, 02:27 AM
Jim McDougall Jim McDougall is offline
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I think your requirement is met by a midi to CV type board . The MPA board can fulfill this function. Each midi note is mapped to a potentiometer position. By feeding a voltage through the electronic pot the output voltage will vary by note number and you can use this to feed the input of a VCO. It will be linear function which is what most VCO's typically require. For really precise control many VCO's cover the note range in two or more blocks and require switching as the note range changes. You could use the other three pots on the board to manipulate this.
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Old 06-24-2012, 05:16 AM
Cynosure Cynosure is offline
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Thanks for the response Jim. From what I read here in these forums, people were saying that these boards are not precise enough to output an accurate CV control. I think I read that it is 128 steps in the pots, which means that the notes will likely always be a little off.

Has anyone tried it?

I really don't need a CV voltage, just the frequency of each note as a pulsewave. I have read about the arduino being able to do it, but I don't have one and thought this might be a better option for around the same price since it comes already programmed and ready to use.
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  #4  
Old 06-24-2012, 03:37 PM
Jim McDougall Jim McDougall is offline
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john probably needs to jump in here, but the musical standard for a VCO was based on 1V per octave -- goes back to pre midi days with the early plug together modular synths. The reference to 128 steps has two points -- one midi controllers only have 128 steps defined according to the midi standard and -- two the digital pot chips are based on 8 bit values. However the largest usable keyboard - piano only has 88 keys or about 7 octaves and a bit which is still within the 128 step range. Since the pots are linear then you will get accurate repeatable voltages.

John will have to confirm that the board output will conform to a 1V per octave based on a 5V input to the pot.

A 1K trimpot on the input side of the pot could allow for fine tuning .

As to the comments about precision, you need to understand the context -- they are trying to replace existing pots in current equipment and in many cases the circuits are very sensitive to specific voltage values. Midi by definition for controllers is 128 steps and for these circuits that is not precise enough - for example continous controller value 0 when mapped based on 128 steps is not 0 volts because 5V/128 is not 0 - but the circuit they are trying to use the digital pot in wants a true 0 volts at one end.

By definition, a keyboard is a stepped value instrument so it is a different and easier situation
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  #5  
Old 06-25-2012, 07:25 PM
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John John is offline
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Quote:
Originally Posted by Cynosure View Post
Is it possible to use this or one of the other controllers to play the frequency of the most recently pressed midi note with logic level pulses?

For example, pressing A4 will output on and off pulses at 440Hz.

I need something to do both this and send an ON logic pulse every time a note is pressed (which i see that some of the controllers here already do).

If there can't work like that, then could you recommend an easy method for controlling the frequency of a simple oscillator? It is for music, so it needs to be precise.

Thanks!
Hi Cynosure, welcome.

No HL product currently has this feature, but I've been considering it for the MD24 for some time.

I'm already planning on adding more general-purpose PWM output, and note-pitch-frequency output would probably fit in there pretty well. So the next MD24 firwmare update would be a good time to add it.

I added your request to the MD24 feature discussion thread as a reminder. There is a good chance that I will include it. The MD24 is next up for a firmware udpate after MIDI CPU 1.3 gets sorted out.

If you're in a DIY mood, you could also check out the source code of the NTH when it is released next month. I'll probably be using the same algorithm for the MD24 frequency output, more-or-less.
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  #6  
Old 06-27-2012, 11:36 PM
Cynosure Cynosure is offline
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That is great news. Thanks for including it. I will keep an eye on the forums here for an update.
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  #7  
Old 06-11-2014, 03:22 AM
jpmaus jpmaus is offline
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Quote:
Originally Posted by Jim McDougall View Post
I think your requirement is met by a midi to CV type board . The MPA board can fulfill this function. Each midi note is mapped to a potentiometer position. By feeding a voltage through the electronic pot the output voltage will vary by note number and you can use this to feed the input of a VCO. It will be linear function which is what most VCO's typically require. For really precise control many VCO's cover the note range in two or more blocks and require switching as the note range changes. You could use the other three pots on the board to manipulate this.
Instead of starting a new thread (1V/OCT MPA), I thought I'd ask someone here. Supposing I didn't want to flash the MPA's PIC or use SYSEX messages, can anyone suggest a good software for "re-mapping" MIDI events in the way described above by Jim? That is, something that can "re-map" MIDI Note Events (e.g., C4, C#4, D4, etc.) to predesignated CC values (i.e., pot positions, 1-127). Any specifics would be appreciated. I tried googling it, but the keywords involved here are all too generic to find what I'm looking for. Thanks!!
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  #8  
Old 06-13-2014, 04:27 PM
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John John is offline
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Quote:
Originally Posted by jpmaus View Post
Instead of starting a new thread (1V/OCT MPA), I thought I'd ask someone here. Supposing I didn't want to flash the MPA's PIC or use SYSEX messages, can anyone suggest a good software for "re-mapping" MIDI events in the way described above by Jim? That is, something that can "re-map" MIDI Note Events (e.g., C4, C#4, D4, etc.) to predesignated CC values (i.e., pot positions, 1-127). Any specifics would be appreciated. I tried googling it, but the keywords involved here are all too generic to find what I'm looking for. Thanks!!
Hi Jpmaus,

There is always Max/MSP, which can translate just about any kind of data into anything else, and has built-in objects for manipulating MIDI message data.

If you want something a little more specialized, you might try this:

http://www.bome.com/products/miditranslator

I haven't used it, but I am a fan of other Bome products like SendSX.
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