FLXS1 CV out calibration?



I recently purchased FLXS1 and am loving the amazing features however with my unit there is a serious flaw in that the quantised output isn’t 1/v octave .if you start at c1 by c2 it’s outputting like an f or something- I’m in chromatic scale btw and on firmware 18a. the VCOs are tracking fine using metropolis/rene/pro 2 etc

Is there a way to calibrate so it outputs correct voltage ? It’s driving me crazy!

any help much appreciated


Surely this is quite a big issue ,has no one else experienced it?

i’ve made sure there are no voltage offsets etc

is there calibration page i am missing?

thanks for any help!


Yeah I’ve noticed and was trying to trouble shoot maybe this same issue last night. Haven’t pinned it down yet but it seems over an octave I lose tracking bad. My other “sequencer” is marbles and it isn’t the easiest to have a predictable note to tune off of.

I’m going to dig into this more. I thought it was my oscillator but then realized none of them are tracking well with the flxs.

Going to use another setup to test it’s
I don’t remember it being off with the previous firmware but my setup has grown since then


I third this; have seen some weird stuff too with the 1v/oct out. Last night I was using the cvB output in quantized mode and had to adjust the offset voltage per note to keep it in tune. Like ndoemusic, I haven’t been able to pin down exactly what it’s doing or when it does it.


Has anyone tried rolling back the firmware. Is it firmware specific issue?


Not yet. I’m goin to make sure it is the flxs first.

I’m on 18a


I’ve had a few euro sequencers that had secret calibration routines, hopefully the FLXS1 is is the same :slight_smile:


I have the calibration routine for FLXS1 that purportedly works for all post Kickstarter modules, Kickstarter modules have a different input resistor value and according to Tenkai must be on the firmware version beta17i_martha for the calibration to work. At the time he also told me that he was planning to update the calibration process so that it worked for all modules.

If you are on a Kickstarter module you need to flash beta17i_martha for this calibration to work!

Link for beta17i_martha: https://www.dropbox.com/s/e1195edobcnypvg/flxs1_beta17i_martha.hex.zip?dl=0


Then you can calibrate your module. Here are the calibration instructions:
Make sure that no cables are connected to FLXS1
Press shift+tempo+play buttons simultaneously to enter calibration mode
Scroll down so that one of the numbers is highlighted
Set the Zero point for each of the 4 input channels
Press and hold each of the 4 channel buttons for at least 2 seconds
Set the 3v scale for each of the 4 input channels
Connect a 3v source to input CV1
Press and hold the step button to the right of the CH1 button
Connect the 3v source to CV2
Press and hold the step button to the right of the CH2 button
Repeat for CH3 and CH4
Press Shift+CH1 simultaneously to save input calibration
Inputs are now calibrated
Go back into calibration mode: press shift+tempo+play buttons simultaneously
Scroll through options until you get to the second page
Using patch cables, connect outputs cv1a, cv1b, cv3a, cv3b to inputs CV1-4
It doesn’t matter if they are connected in the right order, the software will sense which is connected to which.
Press channel button 1
Wait for a 45-90 seconds. Calibration is happening, but there is no visual feedback. The unit will appear frozen during this time
Once the values have updated, connect outputs cv2a, cv2b, cv4a, cv4b to inputs CV1-4
Press channel button 1 and wait again.
Press shift-ch1 simultaneously to save calibration.
Calibration is complete!

I hope this helps!


Well I downgraded did the calibration and it definitely helped I can get some decent tracking on the “a” outputs of every channel. The “b” outputs seemed to be outputting the right voltage under 17i Martha although I had other glitches on that FW. But when I went back to FW 18a the “b” output seems to be outputting the wrong voltages .

Only checked it with my plaits but will investigate further

The calibration process wasn’t very clear at first but it’s oretty easy once you understand

Maybe will try 19 to see what the behavior is.


I used the calibration process on 19a and i have run my outputs through an o’tool. Before and after there is a big improvement, far nearer the the 1v per octave through the entire scale, maybe not perfect as o’tool isn’t the most accurate meter in the world.


Do you have a kickstarter unit or after?


Bought used. Is there any obvious way of telling?


I don’t know at all. I think there were 77 backers. But I don’t know what serial numbers are for the kickstarter and not


Well the jury is still out. I can only seem to get ok tracking out of my flxs. If I check the oscillators with my marbles or voltage block I can get better tracking. So I think I need to calibrate it but I have a kickstarter unit.

I’ll have to send a message to Tenkai


This firmware is only for kickstarter modules, and the calibration settings are slightly different since I changed the input impedance for the CV input stage in later modules.

If you have a serial number that is 178 or below, you have a Kickstarter module.

The calibration steps listed above should work with any module, but kickstarter modules will have a more accurate calibration on beta17i_martha.hex. Any other module will have a different input impedance, so the calculations are slightly different as it is a self calibration mode.

That being said, you can also manually trim the outputs in the calibration menus, but its a bit complex. Is anyone on this thread still having calibration issues?



Thanks Ten, on looking at my module it’s numbered 121 so this will help, although mine was tracking relatively normal, will give this a whirl :slight_smile:


i have just been through the calibration process and my outputs are all exactly 0.05v bellow values e.g. (1v = +0.954v). I have no idea what this means in musical terms and tracking. Is there anyway to get it nearer?


Yeah after calibration might be got a little better but I’m getting a trim or scaling issue. I’m going to try and calibrate under Martha. Only issue was Martha was really buggy when I tried and downgrading if was getting freezes. Would like an updated calibration for the Kickstarter units

Any tips on how to adjust the output manually. I know there are two number ranges for each output but I don’t know what they reference. Would like to be able fine tune them.

Number were read on a mordax data. Wish I could get 3 decimal points out of data

@ -2v I get -2.06
@ 0v =0.01
@ 3v = 3.03/3.04
@ 6v = 6.07
@ 8v = 8.08
@10v = 9.97


I’d say these values are good enough to not worry too much, but saying that would be good to know how to manually get these spot on.


So here are the results of the most recent calibration.

The first set of pictures are flxs and plaits into mordax data and ableton

I tunes the plaits to C2. You can see that I am off 13ct when I go +/- 1 octave from C2.

Now as a quick comparison this is out of the varigate into plaits into mordax data.

That range at least 3 octave with a lot less pitch drift.