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Dave G

Confused about pitch bend values vs. RPN (Pitch Bend Sens)

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Posted (edited)

I'm trying to learn the basics of drawing a pitch bend in the PRV controller pane and exactly how RPN (Pitch Bend Sensitivity) affects this.

I'd like clarification on how the pitch bend works, how far up/down it goes, what the values mean, and how the RPN affects pitch bend. Here are a few observations:

1) I load an RPN controller into the Controller Pane. The meter goes from 0 - 16,383.

2) I load a Wheel controller into the Controller Pane. The meter goes from -8,192 - 0 - 8,191.

I've tried Google searching and YouTube'ing for literally an hour, but still confused. What I've learned was that the Wheel controller offers a range of four notes/semitones (2 up, 2 down from 0). But I don't exactly know what RPN adjustment represents.

My questions:

1) What do the RPN and Wheel values equate to in regards to notes/semitones?

2) As an example, how would I draw a pitch bend/figure the values from a) one note to another and b) the same note on another octave?

3) How does the RPN affect pitch bend?

4) How do I know the Wheel value I've reached accurately represents the target note?

Attached is a sample image with both events going to approximately 4,096.

Any guidance is appreciated. Thanks! :)

EDIT: The RPN controller doesn't seem to work in SoundCenter, but it is very pronounced in TTS-1.

bend.JPG

Edited by Dave G

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The RPN (which is number 0) that controls the pitch bend is in steps of 128. Each 128 increment adjusts the pitch bend rage by a semi tone.  With most synths, the default range is 2 semi tones up and down.

Say you want the pitch bend to be 3 semi tones up and 3 semi tones down.  For this you would issue a RPN 0 value of 384.

Say you want the pitch bend to be 12 semi tones up and 12 semi tones down.  For this you would issue a RPN 0 value of 1536

So the formula is RPN  0  128 x semitones required.

Of course, this will only work if the synth you use responds correctly to the Roland GS or Yamaha XG standard.

You already correctly stated that the actual pitch bend values from -8,192 - 0 - 8,191.  This is necessary because of the higher resolution required for pitch bend - especially when using the higher ranges. 

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Dave, do you have a keyboard with a Pitch Bend and/or Mod Wheel on it?  My guess is no, which is why you are asking how to approximate it using the PRV.

But if you did have one, it's quite helpful to record some MIDI movement into your MIDI track of CbB, and then study the curves.  You can learn a lot from that.  Of course the curves are completely logical once you see how they appear based on the movement of the PB or Wheel, but it is quite helpful.

So, if you do not have a keyboard to study first hand, there is another great way of ascertaining this knowledge:

Download a free MIDI song that has a keyboard part that you are fully aware utilized PB and/or ModWheel in the performance, open that MIDI song with CbB, and then look at the MIDI curves in the track of that keyboard part!

The MIDI programmers for MIDI songs actually do a quite excellent job at perfecting these types of things.

Let me think for minute on a decent example for you to download.... I'll be back in a minute with a link.

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Posted (edited)

Okay... I think these 2 songs by Boston are super examples.  Both the  lead guitar AND keyboard parts (B3 organ) have Pitch Bend going on, especially during the bridge on both of these songs -- Smokin', and Hitch a Ride.

Here's a link to where you can download those song files for free so you can open them with your CbB DAW and begin studying the MIDI curves of said tracks.

https://www.midiworld.com/search/?q=boston

Edited by Toddskins
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Posted (edited)

Thank you both for the concise explanation. I seem to understand that a wheel controller set to +8,191 increases by two semitones/notes. And RPN 1,536 allows the wheel to produce a full octave bend (12 semitones/notes).

I tested this by

  1. drawing a C4 note with a wheel +8,191 (two-note bend) at measure 2
  2. resetting the wheel to 0 at measure 3, and
  3. drawing a straight D4 note (two notes up, per C4) at measure 3.5.

Screenshot attached.

Remaining questions:

  • Is RPN only required if my bend Wheel requires more than two semitones/notes (+8,191 >)?
  • Does RPN 1,536 (12 semitones/notes) completely override the max bend Wheel setting of two semitones/notes?
  • Can one do a pitch bend of more than an octave if desired?

Thanks again.

Bend example.JPG

Edited by Dave G
Reworded questions, included image

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Posted (edited)

In any synths I have used there is a pitch  bend setting for range which can be set to different values--0 for no pitch bend, or any number of semitones, intervals, or octaves. The full range of the wheel's movement is then mapped to the pitch bend range.  For example, I can set the PB range to a perfect fifth. In that case, moving the wheel up full bends a note (or notes) up a Perfect Fifth and moving the wheel completely down lowers the note(s) by a Perfect Fifth. Likewise if I set the PB range to 2 octaves or 3 octaves, etc. the wheel changes the pitch based on the range set in the PB range parameter.

EDIT: To see what midi data TTS-1 responds to (such as PB range) see the document available through TTS-1's HELP button.

Never mind; I don't use PRV and evidently the PRV has its own set of rules for handling MIDI data.

 

Edited by User 905133

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25 minutes ago, Dave G said:

Remaining questions:

So RPN is not required unless I'm using a Wheel of more than two semitones/notes (+8,191)?

Does that mean RPN 1,536 (12 semitones/notes) completely overrides a Wheel setting of two semitones/notes?

Is it just assumed that it would be max 2 semitones without RPN? Or can one potentially do a pitch bend of more than an octave?

Thanks again.

 

RPN is not required unless you want the range to be a value other than 2.  In other words, most synths default to a range of 2.  However, I usually put a RPN 0 256 and a pitch bend =0 at the start of my MIDI tracks to prevent wrong notes caused by a pitch bend that is still active.

Yes, RPN 1,536 completely overrides a Wheel setting of two semitones/notes?

You can do a pitch bend of more than 2 octaves.... just apply the formula I gave you.  For example.  24 semi tones would be RPN 3072 (128 x 24)  - as long as your synth can handle the range.

One thing you have to watch with large ranges is that you might hear the steps as the pitch rises.  If that happens, then portamento would come the the rescue there.

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I did discover one more thing per the visual example I posted above, but on a new instance of this I just created:

The pitch bend occurs perfectly on that first note. However, the second note is slightly louder than the first. This is a TTS-1 Synth Lead instrument that has a sustain, and I confirmed the Velocity is the same level on both notes.

Thoughts please?

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38 minutes ago, Dave G said:

I did discover one more thing per the visual example I posted above, but on a new instance of this I just created:

The pitch bend occurs perfectly on that first note. However, the second note is slightly louder than the first. This is a TTS-1 Synth Lead instrument that has a sustain, and I confirmed the Velocity is the same level on both notes.

Thoughts please?

That's probably a characteristic of the synth itself - or even the particular patch. 

I tried was the patch SAW and natural lead and I that did not happen here - In fact in 20 years of using pitch bends, I have never had that issue....

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