Can you check if Marbles’ miscalibration is on the input or output side?

Disable the external processing mode. Set STEPS fully CW, SPREAD fully CCW, and turn BIAS. It should generate perfect octaves. In particular, if BIAS is set to its minimum position (with the unipolar output range), the output should be 0.000V and should not cause any detuning when patched into a VCO. If all goes well at this step, then the miscalibration is on the input side, if not the miscalibration is on the output side.

Also, regarding your other question… I haven’t had the time to try on a real module, but I looked at the code and came up with the beginning of an explanation. In short, Marbles has three “output things”. When it’s set to external processing mode, with a common clock, only one “output thing” is active and records the notes. The two other “output things” are slaved to the first one and replay the sequence shifted in time, they don’t see the input signal. If you remove the common clock, these two other “output things” will no longer be slaved to the first one but they haven’t recorded any note because they were slaved, so they are stuck with whatever they were doing before you enabled external processing mode. I think I can come up with a software fix for that.


with 5v unipolar , it looks within a few cents of being perfect.
(at least first 4 octave, 5th is off… but perhaps this is hitting the limit of pitch input on plaits (around 6khz?) or something else)
there is about 15cents off, for BIAS = 0 and no jack… which seems pretty close to me.

so Marbles is good :slight_smile:

I reckon its probably the sequencer, which in turns is likely due to my multimeter…
(as its both marbles and the sequencer ‘track’ plaits properly, perhaps its just a small offset?)
Im also starting to realise perhaps multimeters are not really accurate enough for calibration :frowning:

Im wondering if perhaps the better approach for me is to calibrate the sequencer assuming plaits is calibrated - and then use a tuner, and tune the voltage to get the right pitch.
that’ll work for -3v to +5v … assuming plaits tracks over that voltage range nicely.
(I guess I can use the trick with BIAS you showed above with Marbles, to first calibrate Plaits)

x1-x3 outputs.
thank you for the explanation, really interesting to hear about whats going on.

I’d incorrectly assumed that there was one buffer for ‘random’ values and they were distributed x1-x3,
but thinking about it, that wouldn’t work (in non-ext processing mode) , since when deja vi is enabled for X, you need the same values to go out on each X clock tick - so makes sense it’d store per output.

I guess the manuals description assumes that if you remove the patch cable from X clock, then the buffer for X1 , is copied to X2, X3?

yeah, Ive got a Squarp Pyramid, so my thought was I could save a song with all sorts of different scales programmed in it, then just replay different tracks to program each scale slot.
be a nice way to change things up a bit :slight_smile:

is Marbles fixed to the 5 steps?, or does it just sort the notes into ‘buckets’ of pitches based on frequency of each pitch. e.g. could you have 7 steps, if you create more ‘buckets’.
(Im happy with 1,3,5 … so its just idle curiosity!)

Sorry, not sure what you mean with “5 steps”

There are 5 steps in the illustration to make it look simple, but the actual number is 7.

We’re talking about the number of steps in the scale-carving process.


I was playing with trying to get the pulse length to change on the T side - which Id temporarily forgotten how to do… I knew it was something like T+knob…

and whilst I was trying to figure it out the T mode light started to flash.

I quickly pressed it again, in case Id accidentally triggered a calibration mode…
(as when I check the manual I found this was not how to change pulse length!)

so I went to check the code, to see if I should avoid this again…
is this a way to activate different T models?

enum TGeneratorModel {


sorry, didn’t have time to really dig in the code, apart from spotting this, and that indeed there appears to be a long press (2 secs) which messes with the model selected.

so thought I’d come here to check …
(as i don’t want to screw the calibration on my marbles … by putting in a calibration mode, and randomly pressing buttons :wink: )

I thought the “Bias” parameter was supposed to be able to accept 1v/o but the other night I plugged my Keystep into it and when I hit the keys absolutely nothing happened. An LFO into it worked fine though. Maybe I’m missing something?


3 sec long press on T give you 3 other modes:

-independent Bernoulli
-three states

don’t know how to get the Markov model yet

uint8_t bank = state->t_model / 3;
if ( >= kLongPressDuration) {
if (!bank) {
state->t_model += 3;
} else {
if (bank) {
state->t_model -= 3;
} else {
state->t_model = (state->t_model + 1) % 3;

From memory the markov mode isnt exposed in the ui

thanks - yeah, Id figured it out :slight_smile:
I check the code and it looks like the Markov model is not accessible, perhaps it didn’t work out ?

perhaps we just need to change a line of the code?


I asked about Bias being 1V/oct a while ago. To quote @pichenettes:


Oh interesting. OK. So I’m wondering if I’ll be able to do something else I had in mind then. I’m about to buy a Digitone/Mutant Brain and I wanted to clock and send CV to the Marbles with it. My idea was to send clocks from the sequencer and different CV values per clock to the bias. I’m hoping this will be possible.

Anyone else using sequencers in interesting ways with Marbles?

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Could someone describe the behavior of the 3 other models ?

I can imagine for Divider, but it is more difficult for the 2 others.
Also, what is the difference between complementary and independent Bernoulli ?

from Nino:

For those who might be interested, i just investigated the alternate modes and tried to figure out what they do. I only listened to the t outputs.

Green alternate:
Bias still sets the propability for a trigger on T1 or T3 to occur, but the decision is no longer made between those two. Instead a trigger can occur on both or on no channel according to your settings and the dice.

Yellow alternate:
Polyrhythm machine. One channel gets multiplied, the other divided. Here is what ratios i heard going from 12 o’clock to CW (no guarantee).

T1 T3
x1 x1
/1.25 x1.25
/1.3 x1.3
x1 x1.3
/2 x2
/3 x3
/4 x4
/6 x6
/8 x8

Instant afro/poly machine around 12 o’clock. Made me empathize Olivier’s “when it sounds great with just clicks…” another time.

As i did not explore the default red mode too much i wouldn’t be sure what the alternate does. At first it seems to include patterns with more triggers. It also sounds a lot afro. Yummy.

Then Pichenettes:

Congrats for figuring out green and orange. Red is a variant of the coin toss (branches, normal green) mode, with a third choice in which no trigger is generated.


Thank you very much, i made a reseach with “model”, “bernoulli” and “divider” keywords and didn’t found this post :wink:

is there’s a new firmware for marbles?

It doesn’t look like it. 1.1 is all I’m seeing on the site.

This topic is turning into a big mess…

I’ve created a separate topic for this issue.

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quick question regarding the gate length

Hold the button [E] and turn BIAS to adjust the gate length from 1% to 99%

when I use Marbles with the RATE at 9 o’clock or even slower, I would like the GATE to be a lot shorter than the 1% option. When pinging a filter or JustFriends in Plume mode for example.

It would be great if the GATE where TRIGGER in this case. Could it be possible to modify the code in a way that if someone go full CCW with BIAS, the GATE became TRIGGER?

Or even better, to be able to have in all the BIAS spectrum a possibility to have really short GATE to normal length GATE when using BIAS to change the length?