Issue with Marbles X generator

Hello guys,

I’m new here, as I started recently my discovery of modular.
I have a Marbles module which I love, but I believe I have an issue:
as far as I know, the X generator creates random voltages that, setting the steps know from 12 to 5 o’clock, can be used to drive a volt/octave input of an oscillator.
The issue that I face is that the sound output of the oscillator is out of tune. If I use a tuner, I see that all the notes are +5/10 cents, if the output voltage range of Marbles is set to green (0 to 2V). If I increase the range, the detune increases as well.
I check with other oscillators, that properly respond to keyboards.
Is there something wrong with my module?

I hope I was clear enough
I thank you a lot for your assistance


Did you buy the module new, if so, when? Have you changed any of the scale settings? If you set STEPS fully clockwise do you still get octaves reliably?

Model is new, purchased couple of months ago. Firmware updated.
Scale settings is on major. I’ve overwritten one scale but it was the chromatic one.
I did not try fully clockwise honestly.

I want to figure out if it’s an offset error (all notes are transposed by the same amount +/- 1 or 2 cents), or a scale error (the lowest note is correctly 0V, but as you move away the detuning increases).

Tomorrow I will try to set the scale fully clockwise and post the results.
Any other test to do?

Thank you for your answers!

So, I made the test.
I unplugged everything from Marbles. I used a Mother 32 as oscillator, perfectly calibrated.
Plugged the X2 output to the 1 volt/oct of M32. Set the scale fully clockwise.
The result is that the only note in perfect tune is the 0V C. Higher you go with the octave, higher cents you have of difference. Lower you go with the octave, lower cents you have of difference.
Below a link to the video.


Use the support form on the site, I’ll explain you how to return the module for recalibration.

Hello and thank you for your feedback.
Can I return it to the local shop where I purchased it?


Sure! It’ll just take longer for the module to ultimately be returned to me.

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Thank you. I will evaluate the best option for me.
This level of support is great. You are doing a tremendous job and I love your creations. They made me fall in love with Modular systems.
Have a great day!

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I made a terrible mistake. to calibrate all my gear, I used the Mother 32, that uses outputs -5V - +5V on 1V/oct output.
As I see that modular gear uses 0/+5 that is why everything was not in tune.
I’ve recalibrated everything using a Keystep and now everything works as expected.
I’ve learned something today :slight_smile:

Thank you again!

I’m not sure what you did exactly, but it is not correct to say that Modular gear uses 0 to +5V.

On my modules, CV inputs without attenuverters have a range of -5V to +5V, and when an attenuverter or attenurandomizer is prevent, the range is extended to -8V to +8V.

But if your Mother 32 was not calibrated, it is normal then that the CV from Marbles was causing incorrect notes to be played.

I agree, I have misread some information.
After few times spent testing I believe the problem is with the Keyboard output of M32, that does not properly track 1v/oct but it looks like it is closer to 0.9v/oct. I will test tomorrow with an oscilloscope to confirm it properly.
Mother itself it is calibrated and the internal oscillator respond properly to the kb tracking, but somehow the output is wrong.