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Author Topic: Pitch CV scaling?  (Read 3693 times)

UMCorps

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Pitch CV scaling?
« on: September 21, 2012, 12:52:43 pm »
I'm curious about the scaling of the pitch CV out on my MB compared to the midi implementation.

With the octave set at zero, the middle C on the keyboard generates midi note number 48 (kind of surprising because I'd expected note 60 but not a big deal)

However, the voltage put out at the pitch C/V output for the same note is approximately 4 volts which doesn't seem right to me at all.

It's not a major problem when using the MB with my modular because I can drop the oscillators down far enough to compensate. It is a problem with my Tinysizer though because there isn't enough range on the coarse tuning on the VCOs to bring it down to match the MB oscillator pitch so I can't do unison tuning between the two of them.

So, is there an internal way to offset the pitch CV out on the MB?

Thanks.


Bruno@arturia

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Re: Pitch CV scaling?
« Reply #1 on: September 21, 2012, 04:31:09 pm »
You will not be able to offset the Pitch CV out of the MiniBrute. But what could be done is to tune your MiniBrute, one octave higher. It could be done by turning the VCO offset trimmer.
On the back panel of your MiniBrute, you will find two small holes, of top of the gate selector switch. You can offset the pitch by turning the trimmer that is almost on top of the audio input. Avoid turning the other one (on top of the gate selector) or your machine will be out of tune.
The trimmer can by turned, using a small flat screw driver. To avoid creating short cuts into the machine use a plastic screw driver. you will probably need several turns to depitch by 1 octave

regards
Bruno
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UMCorps

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Re: Pitch CV scaling?
« Reply #2 on: September 21, 2012, 06:06:10 pm »
Hi Bruno.

I considered doing that but then thought it would make things less usable/more messy in the long term.

As it is, I'm transposing midi by +12 in Logic to line up soft synths and the Minibrute, so taking the MB up another octave isn't going to help much there.

With MB octave set to 0, the highest A on the keyboard currently gives up 440 hz or thereabouts. I don't want to change that. I'd normally expect that key to deliver midi note number 69 as well. I know volts/oct is less clearly defined than midi but, even so, it seems odd to be getting 4 volts on the C below this A.

I think all I can do with synths like the Tinysizer that have restricted tuning ranges is use midi instead. For midi note 69, the midi/CV interface on the Tinysizer delivers 3.7 volts which seems to me to be a far more sensible value than that delivered by the MBs CV output.

Basically, what I'm, saying is that, given the MB is tuned to provide approx 440 Hz on the upper A in octave 0, I'd expect that key to generate equivalents to that both on the midi and C/V outputs. And mine doesn't  >:(



Bruno@arturia

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Re: Pitch CV scaling?
« Reply #3 on: September 26, 2012, 04:37:34 pm »
hi,
Quote
With MB octave set to 0, the highest A on the keyboard currently gives up 440 hz or thereabouts. I don't want to change that.I'd normally expect that key to deliver midi note number 69 as well. I know volts/oct is less clearly defined than midi but, even so, it seems odd to be getting 4 volts on the C below this A.

In the new upcoming firmware update, i changed midi note number sent by the keyboard. Midi specification tells indeed that a piano middle C (261Hz) should correspond to 60 midi number.
But regarding CV scaling, MiniBrute provides 0V to 10V CV. that is to say 10 octaves. I don't think it's odd that middle C (midi note 60 over 128) gives you 4V over 10V...

by the way haven't you configure your Tynisizer CV to be limited at +5V? I know their is an option for this in the pc configuration software...

Bruno
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UMCorps

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Re: Pitch CV scaling?
« Reply #4 on: September 26, 2012, 05:02:02 pm »
Thanks for the response Bruno. And thanks for the quick fix of the midi issue.

On the CV side, my bad. I'd assumed the MB was working on a 5 volt scale for CV out. I'll have to have a longer think about how best to match the Minibrute with the Tinysizer's front panel tuning range. Maybe have to look a recalibrating those oscillators instead.

The 5 volt config option only limits the output from the midi to CV converter in the Tinysizer. I don't think it has any direct influence on how the oscillators behave. But I'll check.

UMCorps

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Re: Pitch CV scaling?
« Reply #5 on: September 26, 2012, 10:14:54 pm »
I think I've identified the problem.

The lowest available frequency of the Tinysizer audio oscillators is set by the manufacturer at 33 Hz, so it only needs 3 volts or so to take it up to 261 Hz. And as thats the base frequency, its not possible to manually tune it any lower. It looks like I will need to see if its possible to drop the base frequency of the oscillators to 15 Hz or find a way of applying a fixed offset to the CV from the MiniBrute.

I don't know how common this problem might be or if its just unique to the Tinysizer. Hope the info is helpful anyway.








fanwander

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Re: Pitch CV scaling?
« Reply #6 on: November 01, 2012, 01:46:26 pm »
With the octave set at zero, the middle C on the keyboard generates midi note number 48 (kind of surprising because I'd expected note 60 but not a big deal)

However, the voltage put out at the pitch C/V output for the same note is approximately 4 volts which doesn't seem right to me at all.
Frank from Tomeso directed me to this thread, so I am coming a little late:

To my experience not only the output voltage is too high, but also the VCO plays one octave too high. If I play the Minibrute via MIDI from my JX3P, I'd expect it to be in the same pitch, if the JX3Ps DCO is set to 8". The same with the DX7, with an operator set to coarse tune 1.0. But the Minibrutes VCO sounds one octave higher.

I think the "problem" is, that the CV-output provides a voltage, which is the sum of the voltage derived from the MIDI note  (or keyboard note) and the voltage coming from the bender (or from MIDI-Bend commands).

If you set transpose to the lowest value (-2) and play the lowest note on the keyboard, the CV-output reads  more or less 1Volt. This is done because the pitch bender could decrease the voltage for another 1 Volt. So the sum of "voltage of lowest key" + "bender to lowest position" would be 0Volt.
Assumingly the CV-output is provided from the D/A-converter (and not from an analogue mixer), which can create only voltages between 0 and 10 Volts. So a negative voltage is not possible.

If we change now the VCO offset to one octave lower, as Bruno suggests, then the VCO of the Minibrute would play the right pitch, but still the CV-output is one volt too high (due to the bender).

I think there would be two theoretical solutions: 
1.) do not send pitchbend information to the CV-Out, but send the MIDI-Note CV only. I assume that the D/A does not provide enough outputs to handle pitch bend and notes as separate voltages. So this won't work.
2.) pitch the VCO down (as suggested by Bruno), and additionally add a -1V offset on analogue level to the output socket. This is also a hardware modification and kills the warranty. But it is doable at least.

Btw: I don't know any analogue synth, which includes the bender to the Kbd-Voltage output. Alway the bender is some device which works only internally in the synth.

Florian

Bruno@arturia

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Re: Pitch CV scaling?
« Reply #7 on: November 06, 2012, 10:13:41 am »
Hi Florian,

I'm not sure I understood your request/explanations.
If you feel like that when playing MiniBrute via midi, the pitch is one octave to high.
I made a new firmware that is "still" under test. In this unreleased version, I corrected the midi mapping according to my previous post:
Quote
In the new upcoming firmware update, i changed midi note number sent by the keyboard. Midi specification tells indeed that a piano middle C (261Hz) should correspond to 60 midi number.
But regarding CV scaling, MiniBrute provides 0V to 10V CV. that is to say 10 octaves.
when playing center C on built-in keyboard or receiving Midi note number 60, MiniBrute will output C4=261Hz

Pitchbend does nothing to the output voltage of the CV converter when it's centered. if set to 12semitons, it will add 1v(up position) to -1v(down pos).

Quote
Btw: I don't know any analogue synth, which includes the bender to the Kbd-Voltage output. Alway the bender is some device which works only internally in the synth.
Indeed minibrute does not output Kbd-Voltage but  Kbd+bend, which is in my opinion much useful when using MiniBrute keyboard to control an external VCO using CV. And as explained before pitch bend does nothing to your output voltage if you don't use it.

Mapping for the new firmware  version is as follow
C0 = 16.35Hz -> 0V -> midi 12
C1 = 32.7Hz -> 1V -> midi 24
C2 = 65.4Hz -> 2V -> midi 36
C3 = 130.8Hz -> 3V -> midi 48
C4 = 261.62Hz -> 4V -> midi 60
C5 = 523.25Hz -> 5V -> midi 72
C6 = 1046.5Hz -> 6V -> midi 84
C7 = 2093Hz -> 7V  -> midi 96
C8 = 4186Hz -> 8V -> midi 108
C9 = 8372Hz ->9V -> midi 120

In the firmware you have it's:
C0 = 16.35Hz -> 0V -> midi 0
C1 = 32.7Hz -> 1V -> midi 12
C2 = 65.4Hz -> 2V -> midi 24
C3 = 130.8Hz -> 3V -> midi 36
C4 = 261.62Hz -> 4V -> midi 48
C5 = 523.25Hz -> 5V -> midi 60
C6 = 1046.5Hz -> 6V -> midi 72
C7 = 2093Hz -> 7V  -> midi 84
C8 = 4186Hz -> 8V -> midi 96
C9 = 8372Hz ->9V -> midi 108


Regards
Bruno
Bruno
Arturia Hardware

dalasv

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Re: Pitch CV scaling?
« Reply #8 on: November 06, 2012, 10:56:49 am »
I'm with Bruno, having pitch bend sent out from the Minibrute is crucial.

Peter K

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Re: Pitch CV scaling?
« Reply #9 on: November 07, 2012, 08:00:38 am »
Yes, when I play my Minibrute via midi, it does seem to be out by an octave.  I look forward to the new firmware whenever you get it done. 

Thank you for such a great product; it is an amazing value!

fanwander

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Re: Pitch CV scaling?
« Reply #10 on: December 07, 2012, 04:20:18 pm »

Quote from: fanwander
Btw: I don't know any analogue synth, which includes the bender to the Kbd-Voltage output. Alway the bender is some device which works only internally in the synth.
Indeed minibrute does not output Kbd-Voltage but  Kbd+bend, which is in my opinion much useful when using MiniBrute keyboard to control an external VCO using CV.
It would be useful for sure (I'd really appreciate it!), but then it should output -1V if the the lowest note is pressed and the pitchwheel is at the minimum position. Pitchbend is a bidirectional offset voltage for the standard CV from the keyboard.

Quote
And as explained before pitch bend does nothing to your output voltage if you don't use it.
That was not the point. I'd like to have it affecting my output voltage. But in the right way  ;)

I think the perfect solution is not always possible (in this case it would be a -1V offset after the DA-converter).




Bruno@arturia

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Re: Pitch CV scaling?
« Reply #11 on: December 10, 2012, 10:36:59 am »
Quote
    Quote from: fanwander

        Btw: I don't know any analogue synth, which includes the bender to the Kbd-Voltage output. Alway the bender is some device which works only internally in the synth.

    Indeed minibrute does not output Kbd-Voltage but  Kbd+bend, which is in my opinion much useful when using MiniBrute keyboard to control an external VCO using CV.

It would be useful for sure (I'd really appreciate it!), but then it should output -1V if the the lowest note is pressed and the pitchwheel is at the minimum position. Pitchbend is a bidirectional offset voltage for the standard CV from the keyboard.

indeed pitch bend does not have the expected range between C0 and C1, but obviously, playing and bending around 16Hz? I'am not sure it's a big deal.
But you're right it's not the perfect solution.
Bruno
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noNson of Adam

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Re: Pitch CV scaling?
« Reply #12 on: March 24, 2013, 09:49:47 pm »
Hi
I got a related problem with my Doepfer Dark Energy II connected to my MiniBrute via CV/Gate.


For instance:
If I connect the Doepfer via MIDI (MIDI out of MB to MIDI In of DE) the octaves are matching to each other while playing some notes on the MB Keyboard.
If I am connecting then both with the CV/Gate instead MIDI my Doepfer Dark Energy II is two or three octaves higher than the MiniBrute.


How can I fix this?
Because I want to use MiniBrute and Dark Energy connected via CV/Gate so i can use the MiniBrute Arpeggiator and the two voices (MB and DE) combined.
But with the different octaves it doesn't fit my demand.


Thanks in advance for your help.
« Last Edit: March 24, 2013, 09:54:33 pm by noNson of Adam »

Robbie

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Re: Pitch CV scaling?
« Reply #13 on: March 29, 2013, 01:19:20 am »
^ I was having the same problem with my Doepfer A-111-5/Dark Link combo (which together basically comprise the Dark Energy).  Controlling over MIDI, I had one octave higher on the Doepfer, but could muck around with Learn Mode on the Dark Link, selecting different octaves until they matched.  Controlling the Doepfer via the MB's CV/gate controls, though, produced dog-whistle pitches on the Doepfer, unless I dropped the range to -1, and even then the pitch had to be shifted down in order to match the MB. 

I messed around in the Doepfer manual and found that Jumper 4 was installed (which is not the default).  I popped it out and now, via CV, I have a consistent 2-octaves higher on the Doepfer with the Range set to 0, with the pitch being smack on with the knob set to 5 (12:00, which seems as it should be).

I don't know much about this stuff at all, but I'm kind of excited to learn.  Scratching my head a bit right now, though.

 

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