VCV rack and Keylab mkII

VCV Rack
1

Hi! I’m just starting to learn using VCV rack as virtual extension to my hardware modular. I already understand how to send CV out but I have one question about recieving CV in.

For this purpose I use Keylab mk2 which has build in CV in port. In VCV everything works fine. The LFO signal from minibrute 2s is visible on a scope but I still haven’t figured out why negative values are missing.

image

I tried to convert 0-10V signal to -5-5V using SHAPEMASTER. Thanks to this I have now the whole spectrum with negative values but still there is this gap between waves.

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Is there any solution for converting CC from keylab to -5-5V VCV voltage properly?

2

Isn’t this what happens when you soundcard isn’t DC coupled?

1 Like
3

What input module are you using?

4

I am using CV input of keylab mk2. In midi center it set to 5V.

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5

I am using DC coupled motu m4 interface for sending CV. For receiving Keylab mk2.

6

Sorry I mean inside the VCV lol

So you’re looking for bipolar instead of unipolar?

Levels

Signals should typically be 10V_{pp}10Vpp​ (peak-to-peak). This means that audio outputs should typically be ±5V (before bandlimiting is applied), and CV modulation sources should typically be 0 to 10V (unipolar CV) or ±5V (bipolar CV).

7

As I understand in keylab the LFO signal from module is converted to CC which carries positive values only. That means it is unipolar, right? What I am trying to figure out is how to recieve the whole signal of LFO which includes positive and also negative aplitude.

To be more precise this:

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not this:

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8

If the recieved signal is only positive,
maybe an offset (-5v) would help?,
but then the signal must really be 0 - 10v.

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9

My Minilab outputs 0-10v control voltage into the midi cc-cv module inside of VCV. seems to work fine for everything. Looks like it would need to be a setting inside of MIDI Control Center (software for the Arturia hardware)

Or you can use a module to offset the known voltage like this.

offset
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takes the 0+10 and offsets it to +5 -5.

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10

I tried that, thanks. But it still doesn’t look like a sine wave

image

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11

It looks like the lfo CV signal coming from your keyboard is outputting only positive voltage. gotcha Sorry, still workin on my morning coffee lol

Do you have any lfo options on the keyboard to flip it from unipolar to bipolar inside the midi control center or in the keyboard options itself?

Yeah, don’t listen to me on this one. lol

12

It looks like there is no other option in control center.

13

like a regular lfo inside vcv outputs 0-10v and can be offset like so:

dono
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not sure what would be causing the floor value. because you’re just offsetting the floored value now.

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14

Yeah, it looks like that.

15

complicated lol
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there’s always the complicated way lol

  • red = LFO signal dry
  • blue = replicated floored sine wave
  • red2…= square wave from the edge detector
  • green = rounded out square wave from the filter
1 Like
16

It seems to me, that the keylab is only able to convert positive voltage to Midi-CC. You have to make sure, that you offset the modulation by +5V, before connecting it to the keylab. That way you get a full sine wave in VCV and can offset it again if needed. Some Synths have different behaviour regarding uni-/bipolarity depending on the waveform of the LFO in use. My Take5s LFO (it has no CV-Outs, just as an example) is bipolar when used with a Triangle, but unipolar with a Saw… maybe the minibrute has a similar feature.

BUT: Why do you want to work with an external LFO-Modulation in VCV? There are so many ways to get an LFO in VCV (which is then not quantized to 128-Steps via Midiconversion).

1 Like
17

Good point… I just wanted to modulate VCV modules with same LFO affecting also minibrute 2s.